INTEGRATED INSULATION TEST SYSTEM WITH INSULATION TEST RACK WITH CONDUCTIVE BRUSHES

Abstract

An insulation testing system includes: a carrier for a part to be tested; brushes including respective sets of conductive bristles, the sets of conductive bristles brushing against respective insulated portions of the part; at least one motor configured to i) move the part relative to the brushes and / or ii) move one or more of the brushes relative to the part; and a control module configured to i) control the at least one motor to follow a motion profile, and ii) detect, during movement of the part and / or the one or more brushes, a defect in the insulating material of the part due to a short circuit between one or more of the conductive bristles of the brushes and an exposed conductive element of the part at a location of the defect.

Description

INTRODUCTION

[0001] The present invention relates to continuity testing systems and in particular to an insulation testing system according to the preamble of claim 2 for testing stator windings and other electrical components, as is essentially known from DE 10 2014 107 025 A1.

[0002] Electric vehicles and hybrid vehicles contain traction motors for propulsion purposes. Each of the traction motors contains a stator and a rotor with corresponding windings and conductive bars. The windings and / or conductive bars may be insulated (e.g., have an outer insulating coating). During manufacturing, including the formation of parts and components and assembly, the insulating coatings may not be formed properly or may become nicked, scratched, abraded, etc. This may result in sections of the insulating coatings being missing and / or removed, exposing electrically conductive elements. This exposure may cause a short circuit, impair motor performance, and / or reduce motor life. SUMMARY

[0003] According to the invention, an insulation testing system is presented which is characterized by the features of claim 1 or those of claim 2.

[0004] According to other features, the support for the part is implemented as a rotatable support plate configured to rotate the part with respect to the brushes.

[0005] According to other features, the frame includes rails; the brushes are attached to the rails via brush holders; and the brush holders are movable relative to the rails.

[0006] According to other features, the at least one motor is configured to move at least one of the brush holders along at least one of the rails.

[0007] According to other features, the rails include a first rail and a second rail. The first rail is attached to a clamp and supports at least one of the brushes. The clamp is attached to and slidable along the second rail. A portion of the clamp is rotatable relative to the second rail to transfer the at least one of the brushes between a stowed state and a deployed state.

[0008] According to other features, the at least one motor is configured to move the clamp relative to the second rail.

[0009] According to other features, the control module is configured to rotate the part via the at least one motor while not disturbing a busbar of the part.

[0010] According to other features, the at least one motor is configured to move the part relative to the brushes.

[0011] According to other features, the at least one motor is configured to move one or more of the brushes relative to the part.

[0012] According to other features, the conductive bristles of at least one of the brushes include an end embedded in epoxy resin and held together by a conductive crimp layer. The end of the conductive bristles is connected to a wire via a conductive strip folded over the conductive crimp layer. The wire provides a signal to the control module. The control module is configured to determine whether a defect is present on the part based on the signal.

[0013] According to other features, the epoxy resin contains at least one additive for increased viscosity and / or increased conductivity.

[0014] According to other features, the insulation testing system further includes a frame to which the brushes are mounted and are movable relative to the frame to adapt to different sized parts to be tested.

[0015] According to other features, the brushes include a 'U'-shaped brush including: a first brush brushing a first side of a portion of the part; a second brush brushing a second side of the portion of the part; a third brush brushing a third side of the portion of the part; a first brush holder holding the first brush; a second brush holder holding the second brush; and a third brush holder holding the third brush, wherein the first brush holder, the second brush holder, and the third brush holder are connected to each other.

[0016] Further areas of applicability of the present invention will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are provided for purposes of illustration only. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a bottom view of a portion of a stator illustrating an exemplary defect in an insulating coating; Fig. 2 is a schematic view of an exemplary insulation testing system testing a stator and including a voltage and current balancing circuit in accordance with the present invention; Fig. 3 is a perspective view of an exemplary partial insulation test stand including a partial turntable and movable and stationary brushes in accordance with the present invention; Fig. 4 a side cross-sectional view of the partial insulation test frame according to Fig. 3; Fig. 5 is a cross-sectional view of an exemplary 'U'-shaped brush assembly having three brushes each with sets of bristles according to the present invention; Fig. 6 is a partially exploded perspective view of an exemplary straight brush according to the present invention; Fig. 7 is a schematic diagram of an exemplary insulation testing system testing a stator in accordance with the present invention; Fig. 8 illustrates an exemplary insulation testing method for detecting, marking, identifying, and reporting defects in accordance with the present invention; Fig. 9 an exemplary defect indication procedure according to the present invention; and Fig. 10 is a functional block diagram of another partial insulation test stand including movable brushes and a stationary sub-carrier according to the present invention.

[0018] In the drawings, reference symbols may be used multiple times to identify similar and / or identical elements. DETAILED DESCRIPTION

[0019] During manufacturing, motors may be tested to detect defects, such as defects in the insulating coatings of electrical elements in a stator. The insulating coatings may be inspected visually. This may involve a quality control technician using a magnifying glass to check for defects in the stator's insulating coatings. Such testing is labor-intensive and subject to the technician's limitations. A continuity tester may be used, which applies a voltage to the stator and detects if a short circuit exists. If insulating material is missing at the point where the tester touches the stator, an electric current will flow between the stator and the continuity tester.

[0020] The continuity tester may include a brush with conductive bristles. The bristles can be moved over various sections of the stator, grazing them to detect short-circuit locations (i.e., defect locations) where insulation material is missing. The opposite can also occur if the part (or stator) is moved by the bristles while the brush is stationary. A circuit is used to monitor voltage changes across the brush. When a short circuit occurs, the voltage drops significantly. There are large voltage and current fluctuations between a short circuit present and no short circuit present.

[0021] Large voltage and current fluctuations in a circuit can be damaging to components over time if not properly managed. Consequently, components can degrade over time, and this degradation can negatively impact circuit operation. For example, an A / D converter may have specific voltage and current limitations for operation based on what is being used. If there is any resulting drift in the circuit components, such as resistors or other circuit components, this can lead to voltage response behaviors that cause problems with voltage threshold setting and may not adequately detect a short circuit. Deterioration of the circuit components can cause voltage drift, which can result in subsequent defects going undetected.The drift therefore requires circuit adjustments and periodic recalibration, which includes threshold adjustments. A defect can be detected when the voltage falls below the threshold. As an example, the threshold may be set to 5 volts (V), which is significantly lower than a nominal and / or normally expected voltage (e.g., 24 V). The threshold may be set to less than or equal to 20% of the nominal voltage.

[0022] Drift can also lead to unsafe current levels. If circuit components deteriorate over time and a resulting change in the circuit's expected current occurs, this can lead to current levels in the circuit that may exceed a threshold for perceived and / or actual bodily injury. In addition, higher-than-expected current levels can also be harmful to the components and brush, even if human exposure is mitigated.

[0023] The examples set forth herein include an insulation test system comprising i) a partial insulation test frame with one or more continuity test brushes (referred to herein as brushes) and ii) one or more corresponding voltage and current compensation circuits as described in the Fig. 2 and Fig. 7. The brushes are mounted on the partial insulation test stand along with the part under test. The part is moved relative to the one or more brushes, or the brushes are moved relative to the part so that the bristles of one or more brushes contact exposed conductive elements of the part at locations where insulating material is missing. The voltage and current balancing circuits provide balanced voltage responses at nominal low-current levels, which are detected via the bristles of the continuity test brushes used to detect defects (or short circuits). The voltage and current balancing provides stability, improves the longevity of the circuit components, and provides enhanced functionality that enables the insulation test system to be used in various applications while being safe for human contact.In addition to the specified hardware, the insulation testing system also includes an algorithm for marking defective parts. This algorithm improves sensitivity for better defect detection.

[0024] The examples include an automated system with a turntable to hold a stator and a cradle to hold multiple brushes for inspecting the sides of a welded end and the sides of a crown end of the stator while the stator is rotated. The stator is located on the turntable, with the tabs and / or end faces of the stator held to the turntable via clamps, as described below. Multiple brushes of different types are used to contact the sides of the sections of the stator, such as the three sides of the welded end. According to one embodiment, this is done to ensure that the insulating material completely covers the welds and / or the bare wires of the welded end or other section to be inspected. Multiple brushes may be used to inspect other sections of the stator, such as theThe brushes are designed so that the bristles contact the entire crown area and detect exposed wires within the crown. The test may exclude testing of a stator busbar. The brushes are designed to prevent short circuits between the bristles and the stator core.

[0025] Each of the voltage and current balancing circuits improves safety flexibility by incorporating a capacitor for voltage sharing and a pair of appropriately sized resistors. The resistance values ​​of the pairs of resistors are chosen to produce low-current responses. The capacitors and resistors are connected across the common, negative, and positive terminals of analog-to-digital (A / D) converters. The resistor values ​​are chosen to produce low-current responses during operation and / or at all operating points of the voltage and current balancing circuits. The low-current responses make the test setup safe for the operator. The capacitors produce open-circuit conditions when no electrical short circuit is present. If a short circuit is detected using a brush (e.g.,a carbon bristle brush), the voltage at a positive end of a corresponding capacitor drops, resulting in some voltage drop across the corresponding resistors, so that the voltages of each positive and negative terminal of the corresponding A / D converter remain within a predetermined voltage range (e.g., ±13 V) with respect to a voltage at a common A / D terminal.

[0026] The resistors are selected so that, when a short circuit occurs, the current through the voltage and current compensation circuits is maintained below a predetermined current (e.g., less than or equal to 25 mA, which is imperceptible to human contact). From the standpoint of an incoming analog voltage signal, this would maintain the positive terminals of the A / D converters at the rated operating voltage (e.g., 24 V), while maintaining the negative terminals of the A / D converters at 0 V when no short circuit is present. If an insulation break occurs—i.e., the connection from the brush to the phase conductor is shorted—the following changes occur in a corresponding one of the voltage and current compensation circuits. The corresponding positive A / D terminal is forced toward 0 V.It is worth noting that the positive A / D terminal cannot fully reach 0 V due to the intermittent contact between the brush bristles, but in the case of a solid short circuit, the positive A / D terminal is forced to 0 V. A defect is detected when the positive A / D terminal drops to or below a predetermined threshold (e.g., 5 V) or lower compared to the base or nominal voltage without a short circuit (e.g., 24 V).

[0027] Because the negative A / D terminals are maintained at 0 V, there is a 0 V difference between the positive and negative A / D terminals of the A / D converters, and subsequently the common A / D terminals are also at 0 V. As a result, the resistors (hereinafter referred to as resistors R2, R4, R6, ..., RM) connected across the negative and common A / D terminals of the A / D converters experience a 0 V drop (no current flow).

[0028] When defects are detected, the corresponding capacitors have an available charge to discharge as needed, rather than having a power source supplying the rated voltage directly connected to the short circuit (or defect). This allows a constant voltage drop across each of the capacitors to be maintained while minimizing the amount of current flow in each branch of the voltage and current balancing circuits when the corresponding brushes make intermittent contact with the defects. This is accomplished by maintaining the resistor-capacitor (RC) time constants sufficiently long so that discharging the capacitors does not cause large fluctuations in the voltage drops across the capacitors during the period in which intermittent contact is made between the brushes and the damaged areas.As an example, each of the time constants can be 24 seconds. This results in the resistors (hereinafter referred to as resistors R1, R3, R5, ..., RN) connected between i) the capacitors and ii) the positive A / D terminals and the brushes experiencing mainly voltage drops when short-circuit conditions occur.

[0029] To ensure that the current in the circuit does not exceed anything that the human body could perceive, resistors R1, R3, R5, ..., RN are selected so that in the event of a short circuit, the current does not exceed a threshold value (e.g., 1 milliampere (mA)). This voltage and current balancing operation at all operating points ensures that the entire voltage and current balancing circuits are both safe for human touch and do not introduce current or voltage levels that would damage either the brush bristles or any part under test. The current and voltage levels remain below predetermined thresholds to prevent, for example, arcing.

[0030] If a short circuit is present, the corresponding capacitor can be discharged at a suitable rate for a fast, stable measurement. Current flows through the resistors and provides an analog voltage measurement for the corresponding A / D converter. Once the brush is removed from the fault and the short circuit is no longer present, the capacitor is charged until it returns to an open-circuit state.

[0031] The voltage and current balancing circuits prevent degradation of circuit components by preventing large voltage and current fluctuations across the circuit components in the event of a short circuit. The capacitor and resistor values ​​are selected for improved circuit performance and are chosen to prevent degradation of the circuit components due to parasitic voltages across the resistors. The values ​​are selected to prevent drift in the values ​​of the circuit components. This prevents larger than expected voltage drops and arcing across the brush bristles.

[0032] An electrical circuit design and defect detection analysis algorithm are disclosed to enable the automated system to detect nicks and other defects in stator insulation. Multiple brushes are used to simultaneously inspect the welded and crown ends of a stator. The electrical circuit accommodates multiple brushes and tracks analog electrical responses from multiple voltage and current balancing circuits. The voltage and current balancing circuits enable tracking of analog electrical responses. Multi-channel analog-to-digital conversions are performed while maintaining electrical safety parameters. Additionally, the defect detection analysis algorithm and a human-machine interface display are configured to enable simultaneous defect detection, identification, and reporting, including flagging of the defects to an end user.

[0033] Fig. 1 shows a section 100 of a stator. The stator includes welded wire pairs coated with an insulating material. The section 100 includes a defect 102 in which a portion of the insulating coating 104 is missing, exposing the conductive material 106 of a wire. Fig. 1, a bottom (or welded end) of the stator is shown. The stator includes a lamination stack (or body) 110 having a bottom surface 112 and a plurality of tabs (a tab 114 is shown in Fig. 1). As an example, the insulating coating 104 may be an epoxy resin.

[0034] Fig. 2 shows an insulation testing system 200 testing a stator 202. The insulation testing system 200 includes a human-machine interface (HMI) 204 and a voltage and current balancing circuit 206 connected to a power source 208. The HMI 204 may include a control module 210, an A / D converter 212, a memory 214, a transceiver 216, a display 218, and an audible device 220. The display 218 includes LEDs 222 and / or other visual display and / or indicator elements. The control module 210 receives digital voltage data from the A / D converter 212, which receives an analog input signal from the voltage and current balancing circuit 206. The control module 210 detects defects when the analog output signal across the positive and negative terminals 223, 226 (or the corresponding digital signal) of the A / D converter 212 falls below the threshold value (e.g., 5 V or 20% of the nominal or normally expected voltage (e.g., 24 V)).The normal expected voltage without a detected defect may be 24 V. The control module 210 may indicate the detection of defects via the display 218 and the audible device 220. The detection of a defect, the change (or decrease) in voltage, the time of detection, and / or other related information may be stored in the memory 214. As one example, the detection of the defect may be stored along with a nearest location of the defect relative to one or more reference points on the stator 202.

[0035] The display 218 provides a visual aid to indicate the detection of a defect. This also provides an indication of when a defect is detected. The audible device 220 may provide a loud sound, such as a loud alarm signal, when a defect is detected. The audible device 220 may include, for example, a speaker. The control module 210 may report the detected defects and corresponding information stored in the memory 214 via the transceiver 216 to one or more network devices located remotely from the HMI 204.

[0036] The voltage and current balancing circuit 206 includes resistors R1, R2, and a capacitor C. Resistor R1 has i) a first end connected to a first (or positive) terminal of the A / D converter 212 and to the brush 228, and ii) a second end connected to a first end of the capacitor C and to a positive terminal of the power source 208. Resistor R2 includes i) a first end connected to the second (or negative) input terminal 226 of the A / D converter 212, a second end of the capacitor, one or more of the 3-phase contacts 224, and a negative terminal of the power source 208, and ii) a second end connected to a third (or common) terminal COM of the A / D converter 212. The common terminal COM is separate from and not connected to the two terminals 223, 226.A line 225 is connected between i) the negative terminal 226, the first end of the resistor R2, and the second end of the capacitor C, and ii) the one or more 3-phase contacts 224. The first end of the capacitor C is connected to the positive terminal of the power source 208. A second end of the capacitor C is connected to the negative terminal of the power source 208.

[0037] Resistors R1, R2, and capacitor C are connected in series between terminal 223 and the common terminal COM. According to the example shown, capacitor C is connected between resistors R1 and R2. According to one embodiment, resistors R1 and R2 are directly connected to terminals 223, 226 and directly connected to capacitor C. Resistor R1 may be directly connected to brush 228. Resistor R2 may be directly connected to stator 202.

[0038] For example, resistor R1 may be 20-30 kiloohms (kΩ), resistor R2 may be 400-500 kΩ, and the capacitor may be 500-1500 microfarads (µF). According to one embodiment, R1 is 24 kΩ, R2 is 470 kΩ, and C is 1000 µF. The resistance values ​​of the resistors and the capacitance of the capacitor are selected to provide the RC time constant noted herein. According to one embodiment, the resistance values ​​of resistors R1, R2 are selected to limit an amount of current flowing through stator 202, voltage and current balancing circuit 206, and brush 228.The resistance values ​​of resistors R1 and R2 and the capacitance of capacitor C are chosen i) to prevent arcing and sparking at the bristles 230 when a defect (short circuit) occurs, and ii) to maintain a proper current balance in the circuit under all test conditions that is safe (less than 1 mA) when touched by a human. For example, the resistance values ​​of resistors R1 and R2 can be chosen to prevent the current through the circuit 206, the brush 228, and the stator 202 from exceeding a predetermined threshold.

[0039] The resistor values ​​are chosen to limit the current during all aspects of operation and to balance the voltage load allowed across the channels of the A / D converter 212, such as that associated with terminals 223, 226. According to one embodiment, and regardless of whether a defect is present (a short circuit occurs) or no defect is present (no short circuit), the current is maintained between 25 microamperes (µA) and 1 mA due to i) the arrangement and selected values ​​of resistors R1 and R2 along with capacitor C in the voltage and current balancing circuit 206 with respect to the power source 208 (e.g., 24 VDC power supply) and ii) the A / D voltage channel limits between different channels with respect to the common A / D terminal COM. The resistance values ​​of R1 and R2 can be changed based on A / D behavior limits to maintain the described current behavior.As an example, the channel boundaries may be such that the A / D channels of the A / D converter are within ±10-13 V of the common A / D terminal COM. According to one embodiment, the channel boundaries are such that the A / D channels are within ±10.2 V of the common A / D terminal COM.

[0040] The nominal capacitance of capacitor C is chosen to provide a sufficiently long RC time constant, in conjunction with the R1 value chosen for current level considerations. This is done to provide a stable nominal voltage (e.g., a stable 24 V) for the voltage and current balancing circuit 208 within the time window it takes to determine whether a short circuit has occurred. The R1 * C value can provide a time constant of approximately 24 seconds. This provides a sufficiently long time constant that does not need to be further increased with a larger C value, although the time constant can be further increased. If the time constant is too small, the charging and discharging behavior of capacitor C would affect circuit operation in that the nominal voltage would no longer remain at a stable 24 V if a fault occurs.This can make it difficult to assign a specific defect detection threshold because the voltage response would become complicated with the behavior of the capacitor C.

[0041] The capacitance of capacitor C influences the rate of change of current flowing through stator 202, voltage and current balancing circuit 206, and brush 228. Capacitor C is included as a protector for brush 228 and bristles 230, preventing a voltage surge in the current from power source 208 to the short circuit location. When no short circuit is present, capacitor C is charged. When a short circuit is present, capacitor C discharges. Capacitor C does not fully discharge due to the RC time constant used. This helps limit the current in the circuit during a short circuit event. After discharging, power source 208 recharges capacitor C. If the bristles are moved, the short circuit typically lasts only a short period of time.Without capacitor C, resistors R1 and R2 may degrade due to a short circuit and a surge in the current through resistors R1 and R2. The capacitance and resistance values ​​can also be selected based on the application of use to provide low current consumption for safe operation. For example, the capacitance of capacitor C and the resistance values ​​of resistors R1, R2 can be selected to match various brush head designs used to detect defects. According to one embodiment, the brush is designed to have a low impedance compared to the circuit components. The insulation testing system 200 can be adapted to brushes of various designs.

[0042] The HMI 204 and / or the A / D converter 212 detect an analog voltage across terminals 223, 226. Filtering of the A / D signal is performed by data sampling to remove noise associated with the electrical behavior of the brush bristles. A voltage from the power source 208 is provided via capacitor C, which, in conjunction with resistor R1, provides a stable voltage to the brush 228. One of the 3-phase contacts 224 of the stator 202 is connected to line 225. When one or more of the conductive bristles 230 come into contact with an exposed conductive element of the stator 202, current flows from one of the 3-phase contacts 224 through the stator 202 and to one or more of the bristles 230 in contact with the exposed conductive element. The 3-phase contacts 224 include three contacts; one for each phase of the 3-phase stator 202.According to one embodiment, the three-phase contacts 224 are connected to each other so that current can flow through each of the phases of the stator 202. According to another embodiment, the voltage is provided to one of the three-phase contacts 224 of the stator 202, with the brush connected to the line 225.

[0043] The insulation testing system 200 may be used to test a crown end 240 of the stator 202, as shown, a welded end 242, and / or another portion of the stator 202. The insulation testing system 200 may also be used to test individual electrical components and / or elements, an example of which is shown in Fig. 3. The crown end 240 extends upward from a lamination stack 244. The welded end extends downward from the lamination stack 244. The bristles 230 can be moved along various components of the stator 202 to detect locations where the insulating material is missing.

[0044] The insulation testing system 200 includes software and hardware with tunable A / D voltage thresholds used to mark defects. As an example, the threshold for marking a defect may be set to 5 V, but it may vary for different applications. The control module 210 implements a detection algorithm that detects when the voltage across terminals 223, 226 falls below one of the A / D voltage thresholds and generates a visual and / or audible signal to indicate the detected defect.

[0045] The voltage and current balancing circuit described above minimizes current levels at all operating points, regardless of whether a short circuit is present. The inclusion, selection, and arrangement of the resistors and capacitor as described prevent large voltage and current fluctuations and consequently prevent component degradation over time. This maintains current levels below the thresholds associated with perceived and / or actual damage.

[0046] Fig. Figure 3 shows a partial insulation test stand 300 that includes a partial turntable assembly 302 (which may be referred to as a partial carrier), a frame 304 with the rails 306, the brush support members 308, a first 'U'-shaped brush assembly 310, a first straight brush 312, a second straight brush 314, and a second 'U'-shaped brush assembly (or 'U'-shaped brush) 316. The brushes 310 and 312 are referred to in combination as a gamma brush. Although the Fig. 3-4 show a frame assembly for rotating a part and holding the brushes at fixed positions. The frame can be modified to hold the part in a fixed position and to move the brushes relative to the part. An example of this is shown in Fig. 10 shown.

[0047] The partial turntable arrangement 302 according to Fig. 3 includes a base 320 and a support plate 322 that rotates relative to the base 320 (or the turntable). The turntable assembly 302 may include the part support clamps 324. The support clamps 324 are attached to the support plate 322 and to a part to be tested 326 (e.g., a stator of a motor). The support clamps 324 may be 'C'-shaped and attached to the tabs 328 of a stator core 329. The support clamps 324 may be replaced by tapered-end pins if only one side is tested at a time. If pins are used, the stator would have to be turned over to test the other side of the stator. The part 326 rotates with the support plate 322.

[0048] The part turntable assembly 302 is part of an automated system that includes the turntable 320 with the support plate (or pallet plate) 322 on top. A palletizing system may use at least one pallet to load the part (or stator) to be tested from the turntable 320, and a carriage may transfer the pallet with the stator on top of the turntable 320. The stator may also be transferred (either by a robot or a human) to a fixture located on the turntable 320. The system's brushes, described below, may be activated to move them to control locations ready to contact specific test portions of the stator wires. The angular rotation of the stator is determined by the arrangement of the one or more brushes to test exposed insulated wires of the stator.One or more other brushes may be used by a human or robot to clean any exposed insulated stator wires, e.g. using the system of . Fig. 2 to be checked.

[0049] The stator includes a crown end 330 and a welded end 332. The crown end 330 is examined using the first 'U'-shaped brush assembly 310 and the straight brushes 312, 314. The first 'U'-shaped brush assembly (or first 'U'-shaped brush) 310 includes three brushes arranged in a 'U' shape and formed as part of a gamma brush. The gamma brush assembly also includes the three brushes and the straight brush 312. A single brush member 334 holds the bristles 336 of the three brushes and the bristles 338 of the straight brush 312. The bristles 336 brush against the outer, upper, and inner sides of the crown end 330. The bristles 338 brush against an inner side of the crown end 330. The gamma brush assembly can be moved between being in a deployed state and being in a stowed state, as indicated by arrow 339.This can be accomplished by loosening or tightening a clamp 340 of a pivot arm 341, e.g., via a handle 343. According to one embodiment, the clamp 340 includes a motor, or the clamp 340 is attached to a motor controlled by a control module (e.g., the control module of FIG. Fig. 7). The brush holding elements 308 can be moved laterally along corresponding ones of the rails 306, as indicated by arrows 342 and 345, respectively. According to one embodiment, the brush holding elements 308 have slots that allow the brush holding elements 308 to be moved closer to or farther away from the stator to obtain proper contact with the stator. The brush 314 has the bristles 344. The bristles 336, 338, and 344 can be held in the grooves of the corresponding brush holding elements (or brush holders) 308, which can have internal grooves for the ends of at least some of the bristles 336, 338, and 344.

[0050] The second 'U'-shaped brush assembly 316 includes three brushes arranged in a 'U' shape and held by a single brush element 347. The three brushes of the second 'U'-shaped brush assembly 316 brush against the inside, bottom, and outside of the welded end 332. Another 'U'-shaped brush assembly is included and is in Fig. 4 shown.

[0051] The stator includes a busbar 350 with three-phase contacts 352. The part (or stator) under test 326 can be rotated so that the brushes of the single brush element 334 do not come into contact with the busbar 350. The part 326 can be rotated to test the stator crown portion not covered by the busbar 350. This is more than a 180° rotation and less than a 360° rotation. As shown, the single brush element 334 is at a 90° position relative to the part 326. With the above-specified rotational movement of the part 326, the brushes 310, 312 can contact 360° of the inner side surface of the crown end 330. The gamma brush assembly can be converted to the stowed state to allow the brush 314 to sweep 360° against the outside of the crown end 330. The member 326 is rotated 360° to perform this operation.The second 'U'-shaped brush assembly 316 also sweeps against 360° of the inside, bottom, and outside surfaces of the welded end 332. The data collected for the outside of the crown end 330 may be collected while collecting the data for the inside, bottom, and outside surfaces of the welded end 332.

[0052] Fig. Figure 4 shows the partial insulation test stand 300, which includes the partial turntable assembly 302, the frame 304 with the rails 306, the brush support members 308, the first 'U'-shaped brush assembly 310, the first straight brush 312, the second 'U'-shaped brush assembly 316, and a third 'U'-shaped brush assembly (or third 'U'-shaped brush) 400. The first 'U'-shaped brush assembly 310 includes the bristles 336, including the bristle sets 336A, 336B, 336C of the respective brushes.

[0053] The partial turntable assembly 302 includes the turntable base / turntable housing 320 and the support plate 322. The support plate 322 rotates via a shaft 402 through a (in Fig. 3) motor 401, which is controlled by the control module Fig. 7 can be controlled. A support rod 404 extends through the shaft 402 and is connected to a support member 406, which is connected to and supports the 'U'-shaped brush assemblies 316 and 400. The 'U'-shaped brush assemblies 316 and 400 include the 'U'-shaped members 345, 408 and the laterally extending members 410, 412 connected to the support member 406. The 'U'-shaped brush assemblies 316 and 400 further include the bristle sets 420A, 420B, 420C and 422A, 422B, 422C. The bristles of the bristle sets 420A, 420B, 420C and 422A, 422B, 422C may contain bristles of different lengths.

[0054] According to the example shown, the part 326 to be tested is shown as the above-mentioned stator, which has the crown end 330, the welded end 332, and the busbar 350. The part 326 is held to the support plate 322 via the support clamps 324, which are 'C'-shaped.

[0055] Fig. Figure 5 shows a 'U'-shaped brush assembly 500 having a holder design for three brushes 502, 504, 506 with the respective bristle sets 508, 510, 512. The brushes 502, 504, 506 have the respective wires 514, 516, 518 connected to respective voltage and current balancing circuits, examples of which are shown in Fig. 7. The bristles of the bristle sets 508, 510, 512 are conductive and flexible and are held by the crimps and / or the bristle retaining elements 520, 522, 524. The brushes 502, 504, 506 have interlocking grooves that allow them to be arranged similarly to some of the Fig. 3 shown brushes to remain attached to each other and to be connected to a laterally extending element.

[0056] The holder design (or holder) can be adapted for different stator models, different stator sizes of the same family, etc. The holder includes the plate 521 attached to the brush bodies, with the brush bodies having first respective channels for the wires 514, 516, 518 and second respective channels for attaching the bristle retaining elements 520, 522, 524. The holder can be 'U'-shaped, flat-shaped, or have another shape to accommodate the detection area of ​​the stator's exposed wires. The wires 514, 516, 518 are used to monitor the voltages across the brushes 502, 504, and 506, respectively, to determine the location of a defect (or where a short circuit is detected).

[0057] The bristles (or fibers) of the brushes 502, 504, 506 may be carbon fibers having one end embedded in an epoxy resin to prevent the carbon fibers from "falling out" of the bristle-holding elements 520, 522, 524 and / or breaking. The epoxy resin may be conductive and may contain additives to increase the viscosity of the epoxy resin and / or increase the electrical conductivity of the epoxy resin and prevent wicking (or movement of the epoxy resin along the fibers). The other additives may be zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), or three-dimensional (3D) nanomaterials and depend on the shape and size of the additive. Both nanoparticles and micro-sized particles, such as metallic, non-metallic, polymeric, and non-polymeric particles, may be included. The other additives can be carbon-based nanomaterials and particles, such asContains graphene, graphene nanoplatelets, graphite, fullerenes, carbon nanotubes, carbon black, and carbon dots. The epoxy resin can increase the stiffness of the bristles. Fig. 6 shows an exemplary structural arrangement of a brush that can be used for each of the brushes 502, 504, 506.

[0058] Fig. 6 shows a straight brush 600 and the corresponding bristles 602, a conductive crimp layer 604, an epoxy layer 606, and a conductive strip 608. The epoxy layer 606 is outlined and shown in transparent form to show the conductive crimp layer 604. The bristles 602 include first ends 610 and second ends 612. The first ends 610 are uncoated and / or embedded in epoxy. The second ends 612 are coated and embedded in the epoxy of the epoxy layer 606. The second ends 612 are coated with the epoxy. The epoxy resin may be conductive and connects the second ends 612, the conductive crimp layer 604, and the conductive strip 608. The conductive crimp layer 604 is wrapped around at least three sides of the second ends 612 and is crimped onto the bristles 602, holding them together.According to one embodiment, the conductive crimp layer 604 is wrapped around four sides of the second ends 612. Although this is not shown in FIG. Fig. 6, the conductive strip 608 is folded over the second ends 612 and covers at least one side of the conductive crimp layer 604. The conductive strip 608 covers three sides of the second ends 612. The conductive strip 608 is connected to a wire 614, which may be an output wire used to detect a short circuit.

[0059] The bristles 602 may contain carbon fibers, metal fibers, or other conductive fibers. The density, stiffness, and tear-out strength properties of the bristles may be selected and optimized. The conductive crimp layer 604 and the conductive strip 608 may be formed from metallic materials. According to one embodiment, the second ends 612, the conductive crimp layer 604, the epoxy resin layer 606, and the conductive strip 608 are arranged, configured, and cured within a brush holder. Example brush holders are shown in Fig. 5 shown.

[0060] Fig. 7 shows an insulation testing system 700 testing a stator 702. The insulation testing system 700 is related to the insulation testing system according to Fig. 2, but contains a partial insulation test arrangement 704, such as the partial insulation test frame 300 according to the Fig. 3-4, and a plurality of voltage and current balancing circuits 706 for a plurality of brushes 708 of the partial insulation test arrangement 704.

[0061] The insulation testing system 700 includes an HMI 710. The HMI 710 includes a control module 711, the A / D converters 712 for each of the voltage and current balancing circuits 706, a memory 714, a transmitter / receiver 716, a display 718, and an audible device 720. The display 718 includes LEDs 722 and / or other visual display and / or indicator elements. The control module 711 receives digital voltage data from the A / D converters 712, which receive analog input signals from the voltage and current balancing circuits 706. The control module 711 detects defects when the voltage of the analog output signals (or the corresponding digital signals) falls below the threshold value (e.g., 5 V or 20% of the nominal or normally expected voltage (e.g., 24 V)). The control module 711 may indicate the detection of defects via the display 718 and the acoustic device 720.The detection of a defect, the change (or decrease) in voltage, the time of detection, and / or other related information may be stored in memory 714, as described above and further described below.

[0062] The partial insulation test assembly 704 includes the motors 730 and the brushes 732 and may also include the sensors 734. The motors 730 may include a motor for rotating a support plate for a part, such as the stator 702. The motors 730 may further include motors i) for moving the brushes along the rails and / or relative to respective portions of the part under test and / or ii) for moving the brushes between deployed and stowed positions. The brushes 732 may include straight brushes, 'U'-shaped brushes, and / or other brushes. Some of the brushes may be implemented in gamma brush arrays. The sensors 734 may include motor encoders for determining the positions of the shafts of the motors 730, cameras for monitoring the locations of the brushes 732 relative to the part to be tested, speed sensors for monitoring the speed of one or more of the motors 730, and / or other sensors.

[0063] The stator 702 includes a crown end 740, a lamination stack 742, and a welded end 744. The crown end 740 extends from a top surface 746 of the lamination stack 742. The welded end 744 extends from a bottom surface 748 of the lamination stack 742. The stator 702 has three phases with respective 3-phase contacts 750.

[0064] Each of the voltage and current balancing circuits 706 includes i) a pair of resistors R1 and R2, R3 and R4, ..., or RM and RN, and ii) a respective one of the capacitors C1-CP, where M, N, and P are integers. The number of resistor pairs is equal to the number of capacitors.

[0065] Each of the resistors R1, R3, ..., RM has i) a first end connected to a first (or positive) terminal of a respective one of the A / D converters 712 and to a respective one of the brushes 732, and ii) a second end connected to a respective one of the capacitors C1-CP and to a positive terminal of the power source 760. The first ends of the capacitors C1-CP are connected to the resistors R1, R3, ..., RM and are connected to the positive terminal of the power source 760. The second ends of the capacitors C1-CP are connected to a negative terminal of the power source 760, to a respective one of the resistors R2, R4, ..., RN, to a second (or negative) terminal of a corresponding one of the A / D converters 712, and to one or more of the 3-phase contactors 750.

[0066] Each of the resistors R2, R4, ..., RN includes i) a first end connected to a third (or common) terminal of a respective A / D converter 712, and ii) a second end connected to the second end of a respective one of the capacitors C1-CP, to the negative terminal of the power source 760, and to one or more of the 3-phase contacts 750 of the stator 702. A line 725 is connected between i) the negative terminals of the A / D converters 712, the second ends of the resistors R2, R4, ..., RN, and the second ends of the capacitors C1-CP, and ii) the one or more 3-phase contacts 750.

[0067] The resistors and capacitor of each of the voltage and current balancing circuits 706 are connected in series between the positive terminals of the A / D converters 712 and the common terminals of the A / D converters 712. According to the example shown, each of the capacitors C1-CP is connected between a respective one of the resistors R1, R3, ..., RM and a respective one of the resistors R2, R4, ..., RN. According to one embodiment, the resistors R1, R3, ..., RM and R2, R4, ..., RN are directly connected to a respective one of the terminals of the A / D converters 712 and directly connected to the respective one of the capacitors C1-CP. The resistors R2, R4, ..., RN can be directly connected to the stator 702. The resistors R1, R3, ..., RM can be directly connected to the brushes 732.

[0068] As an example, resistors R1, R3, ..., RM may each be 20-30 kiloohms (kΩ), resistors R2, R4, ..., RN may each be 400-500 kΩ, and capacitors R2, R4, ..., RN may each be 500-1500 microfarads (µF). According to one embodiment, resistors R1, R3, ..., RM are each 24 kΩ, resistors R2, R4, ..., RN are each 470 kΩ, and capacitors C1-CP are each 1000 µF.

[0069] The resistance values ​​of resistors R1, R3, ..., RM, R2, R4, ..., RN and the capacitance of capacitors C1-CP are selected to provide the RC time constants mentioned herein. According to one embodiment, the resistances are selected to limit the amount of current flowing through stator 702, voltage and current balancing circuits 706, and brushes 1-N. The resistances and capacitances are selected i) to prevent arcing and sparking at the bristles of brushes 1-N when a defect (short circuit) occurs, and ii) to provide adequate current balancing in the circuit under all test conditions to maintain safety in the event of human contact (less than 1 mA). The resistance values ​​may, for example, be selected to prevent the current through circuit 700, brushes 1-N, and stator 702 from exceeding a predetermined threshold.

[0070] The resistor values ​​are chosen to limit the current during all aspects of operation and to balance the voltage stress allowed across the channels of the A / D converters 712, such as that associated with the positive and negative terminals of the A / D converters 712. According to one embodiment, and regardless of whether a defect is present (a short circuit occurs) or no defect is present (no short circuit), the current is maintained between 25 microamperes (µA) and 1 mA due to i) the arrangement and selected values ​​of the resistors along with the capacitors in the voltage and current balancing circuits 706 with respect to the power source 760 (e.g., 24 VDC power supply) and ii) the A / D voltage channel limits between different channels with respect to the common A / D terminal COM. The resistor values ​​can be changed based on the A / D behavior limits to maintain the described current behavior.As an example, the channel boundaries may be such that the A / D channels of the A / D converters 712 are within ±10-13 V of the common A / D terminal COM. According to one embodiment, the channel boundaries are such that the A / D channels are within ±10.2 V of the common A / D terminal COM.

[0071] The capacitance ratings of the capacitors are chosen to provide sufficiently long RC time constants, in conjunction with the resistance values ​​of resistors R1, R3, ..., RM, which are chosen for current level reasons. This is done to provide a stable nominal voltage (e.g., a stable 24 V) for the voltage and current compensation circuits 706 within the time window required to determine whether a short circuit has occurred. The RC values ​​can provide time constants of approximately 24 seconds. This provides sufficiently long time constants that do not need to be further increased with larger C values, although the time constants can be further increased. If the time constants are too small, the charging and discharging behavior of the capacitors C1-CP would affect circuit operation in that the nominal voltage would no longer remain stable at 24 V if a fault occurs.This can make it difficult to assign a specific defect detection threshold because the voltage response would become complicated with the behavior of the capacitors C1-CP.

[0072] According to one embodiment, the resistance values ​​of resistors R1, R3, ..., RM and R2, R4, ..., RN are selected to limit the amount of current flowing through the stator 702, the voltage and current balancing circuits 706, and the brushes 732. The resistance values ​​of resistors R1, R3, ..., RM and R2, R4, ..., RN and the capacitances of capacitors C1-CP are selected to prevent arcing and sparking at the bristles of the brushes 732 when defects (short circuits) occur. For example, the resistance values ​​of resistors R1, R3, ..., RM and R2, R4, ..., RN can be selected to prevent the current through each of the brushes 732 from exceeding a predetermined threshold.

[0073] The voltage and current balancing circuits 706 operate similarly to the voltage and current balancing circuit 206 according to Fig. 2. The brushes 732 can replace the brushes 310, 312, 314, 316, 400 according to the Fig. 3-4. The control module 711 monitors for defects detected via the voltage and current balancing circuits 706, the A / D converters 712, and the brushes 732.

[0074] Fig. Figure 8 illustrates an exemplary insulation test procedure for detecting, marking, identifying and reporting defects across multiple brushes (e.g., the brushes after the Fig. 3-4 and 7). The insulation testing method implements a defect detection analysis algorithm that includes the following operations. The operations can be performed iteratively. The operations shown by solid-line boxes can be performed by the insulation testing system 200 after Fig. 2 and / or the insulation test system 700 according to Fig. 7 using the partial insulation test frame 300 according to the Fig. 3-4 or another frame similar to that of the partial insulation test frame 300. Although the operations are mainly carried out with respect to the insulation test system 700 according to Fig. 7, the operations are applicable to other embodiments of the present invention.

[0075] At 800, the lead 725 is connected to the part under test, such as the stator 702 or another electrical component. For example, the lead 725 can be connected to one or more of the 3-phase contacts 750.

[0076] At 802, the control module 711 begins rotating the part according to a motion profile while the brushes pass over the insulated portions of the part. The part can be rotated in increments or in a continuous motion. The part can be rotated while the following operations are performed. The brushes 732 are moved over the insulated portion of the part under test. This includes brushing the bristles of the brushes 732 against the insulated portions so that one or more of the bristles come into contact with any uninsulated (exposed) conductive material of the part. The exposed conductive material is at a voltage applied to the part by the power source 760. When one or more of the bristles come into contact with an exposed portion of the part, a short circuit is created, and the control module 711 detects the voltage drop.The short circuit creates a sharp voltage drop below the threshold level from the nominal (or normally expected) level. The bristles maintain contact with the part while moving relative to the part.

[0077] At 804A, 804B, ... 804P (collectively referred to as operation 804), the control module 210 begins monitoring the voltage at the input terminals of the A / D converters 712 and consequently at the bristles of the brushes 732. This may include determining a location of the bristles of the brushes 732 relative to one or more reference points of the part under test. According to one embodiment, the bristles of the brushes 732 are initially in contact with respective locations on the part for which the control module knows the coordinates, and then the brushes 732 are moved. As one example, the movement, including location and velocity information, may be tracked by the control module 711 based on the outputs of the sensors 734.

[0078] At 806A, 806B, ..., 806P (collectively referred to as operation 806), the control module 811 determines whether a defect has been detected. If one or more defects have been detected, operation 808A, 808B, ..., 808P (collectively referred to as operation 808) is performed for the one or more brushes for which a defect has been detected; otherwise, operation 812A, 812B, ..., 812P may be performed for the one or more brushes for which no defect has been detected. A defect is detected when there is a short circuit between one or more bristles of one or more brushes 732 and one or more exposed conductive elements of the part.If the part is a stator, a short circuit may be present between one or more bristles and one or more exposed wires of the stator and consequently between one or more bristles and one or more of the 3-phase contacts 750 of the stator 702.

[0079] At 808A, 808B, ..., 808P (collectively referred to as operation 808), the control module executes a defect indication procedure described in Fig. 9 is illustrated.

[0080] At 900, the control module indicates the detected defects visually and / or audibly via one or more indicators, such as via the display 718, the LEDs 722, and / or the audible device 720. According to one embodiment, a message is displayed via the display 718. The message may include information regarding the detected defects, including the location of the defects, the time at which the defects are detected, the voltage drops across the A / D converters 712 experienced as a result of the defects, the rates of the voltage drops, how long the defects are detected, etc. According to another embodiment, the message is sent from the HMI 710 to another network device via the transceiver 716. The defects may be detected for short periods of time depending on the size of the defect and the speed of movement of the corresponding brushes relative to the part under test.The location of the defect can be specified with respect to one or more reference points on the part to be tested.

[0081] As one example, a ring may be attached to the welded end 744 and include timed indices, and / or the lamination stack 742 may include the reference points. The indices and / or reference points may be used to determine the locations of detected defects. According to one embodiment, the control module 711 marks the defects by illuminating red LEDs (one for each defect) or by displaying red icons (one for each defect). Green LEDs may be illuminated and / or green icons may be displayed for the brushes that do not detect defects. The display may include an LED and / or display an icon for each brush indicating whether or not a defect has been detected using that brush. According to another embodiment, the control module 711 marks the defects by triggering an audible defect alarm signal.

[0082] At 902, the control module 711 records the information regarding the detected defects. At 904, the brushes 732 are removed from the part (i.e., moved to stowed positions away from the part). At 906, the voltage of the voltage and current balancing circuits 706 returns to the nominal levels.

[0083] At 908, the control module 711 ceases to indicate that a defect has been detected, thereby returning the one or more indicators back to normal states. For example, the audible device 720, which may provide the audible notification (or audible alarm), turns off. The illuminated LEDs turn green or off. The displayed icons indicating an existing defect change from red to green or are no longer displayed. The operation 810A, 810B, ..., 810P (collectively referred to as operation 810) after Fig. 8 can be executed following operation 908.

[0084] At 810, the control module 711 may determine whether there is more of the part to be inspected. If so, operation 804 may be performed; otherwise, the method may end.

[0085] At 812, the control module 711 may compile the defect information for each of the detected defects, including the locations of the defects and other related information. The compiled information may be stored as a compiled information file in memory 714.

[0086] At 814, the control module 711 may report the compiled information in a compiled overall report on the presence of defects and / or portions thereof via the display 718 and / or the audible device 720. The report and / or the compiled information may be transmitted to a remote network device via the transceiver 716. This information may include the locations of the defects, identify one or more defect zones in which defects are located, and / or include other related information (e.g., any of the information mentioned above). This may include an indication of the location of the defects on the part, the times at which the defects were detected, and / or other information indicating the locations of the defects.

[0087] Based on the detected defects and the corresponding information, the defects can then be inspected and repaired. The control module 711 can rotate the part to enable manual inspection and / or repair of a defect. If a defect is beyond repair and / or if there are too many defects, the part can be recycled or discarded. Based on the collected information, the control module 711 can indicate whether the part is repairable and / or whether the part should be recycled or discarded.

[0088] Fig. Figure 10 shows a partial insulation test stand 1000 containing movable brushes 1002 and a stationary part support 1004 that holds a part 1006 in a fixed position. Any number of brushes may be included. The brushes may be any of the types mentioned above. Fig. 10 is provided as an example and shows an example arrangement of brushes with respect to a part, where the brushes may be in various other arrangements with respect to the part. The part 1006 may be a stator or another type of part. The brushes 1002 may be held by brush holders 1008, which may be attached to one or more support members. An example support member 1010 is shown. One or more motors may be included to move the one or more support members and consequently the brushes 1002. The motors may be attached to a frame 1011. A motor 1012 is shown moving the support member 1010. The motors move the brushes 1002 with respect to the part. This movement may be a rotational movement or a linear movement. Motors may be included to move the brushes between deployed and stowed states.The brushes 1002 may be connected to the voltage and current balancing circuits of an insulation testing system, as shown in . Fig. 7. The part 1004 may also be attached to the frame 1011.

[0089] The exemplary automated system disclosed herein detects nicks on exposed wires at the welded and crown ends of an assembled stator. The brush holders are adjustable to accommodate different stator sizes within the same family and different types and designs of brush heads. This provides a high degree of flexibility in meeting the requirements of a specific application. The automated system can be configured with stationary brushes and rotate a stator relative to the brushes, or it can be configured with a stationary stator support member and rotate (or move) the brushes relative to the stator. The brushes are configured to detect exposed wires at the welded and crown ends. The brush holders are optimized for each specific stator size and design.According to one embodiment, the ends of the carbon fibers are embedded in an epoxy resin and inserted into the grooves of the brush holders. Additives (such as carbon black) may be used to increase the viscosity of the epoxy resin, prevent bristle pullout, provide low, consistent interfacial resistance, and prevent wicking. The bristle lengths of the 'U'-shaped conductive brushes are selected for each application and chosen to avoid significant bristle overlap i) at bend portions (or 90° angled portions) of the 'U'-shaped holders to allow the bristles to be properly deflected, and ii) at contact portions (or contact ends) where the bristles make contact with the part under test.

[0090] The examples described above include a circuit design for multi-channel analog-to-digital conversion of brush signals while maintaining electrical safety parameters for operators. The circuit design allows for simultaneous tracking of analog signals for each brush integrated into the automated system. The multi-channel circuit design can include multiple brushes to fully test each isolated section of a part (perform electrical testing of each isolated section of a part).

[0091] An analysis algorithm is provided that individually monitors the digitally converted signals from each brush while tracking the motion profile of either the brushes or the part under inspection as the brushes or the part are moved (e.g., rotated) relative to each other for both defect identification and location determination. An HMI display is used for simultaneous defect detection and reporting (e.g., marking). According to one embodiment, the locations of the detected defects are reported to an end user and / or a remote network device when a repeatable motion profile is used for inspection.

[0092] The test circuit and analysis algorithm disclosed herein enable the automated system to test the insulation of wires at both ends of a stator assembly for cuts, nicks, and other defects. The test circuit has enhanced circuit performance to prevent degradation of electrical circuit components due to parasitic voltage across the test circuit's resistors. The analysis algorithm is used to monitor the digitally converted signals from each brush individually while tracking the motion profiles of the brushes and / or the part under test as they are moved relative to each other for both defect identification and approximate location. An HMI display is updated for an end user to enable simultaneous brush detection and reporting for flagging defects.The HMI display can be used as a visual aid to identify when and where a fault occurs. If a short circuit occurs, the corresponding fault can be indicated via the HMI on a screen and / or with an audible alarm.

[0093] Safety flexibility is enhanced by including capacitors in each analog-to-digital channel for voltage distribution within the circuit. Resistors with selected resistance values ​​are included to produce low-current responses, making a test setup safe for an operator and preventing electrical arcing between the brush bristles and the part under test. The capacitors produce open-circuit conditions when no short circuit (or short-circuit conditions) are present. When a short circuit (or short-circuit condition) is detected by a brush, a voltage is dropped at the positive end of the corresponding capacitor, resulting in some voltage drop across the corresponding pair of resistors, so that the voltages of each positive and negative terminal of the corresponding A / D converter remain within a predetermined voltage range (e.g.,±13 V) with respect to a voltage at the common A / D terminal. Once the brush is removed from the short circuit location, the capacitor is charged until it returns to its open-circuit state. The voltage drop due to the short circuit and the amount of current flowing through the circuit due to the short circuit are limited. This helps prevent circuit deterioration and makes the circuit safe for human contact. The capacitor and resistor values ​​are set to meet application requirements while providing low current draw for safe use by an operator.

Claims

[1] Insulation test system (200) comprising: a support for a part to be tested (326); a plurality of brushes (312, 314, 316) including respective sets of conductive bristles (336, 338, 344), the sets of conductive bristles (336, 338, 344) brushing against respective insulated portions of the member (326); at least one motor (401) configured to move the member (326) relative to the brushes (312, 314, 316); and a control module configured to i) control the at least one motor (401) to follow a movement profile, and ii) during movement of the part (326) and / or the one or more brushes (312, 314, 316), detect a defect in the insulating material of the part (326) due to a short circuit between one or more of the conductive bristles (336, 338, 344) of the plurality of brushes (312, 314, 316) and an exposed conductive element of the part (326) at a location of the defect. [2] Insulation test system (200) comprising: a support for a part to be tested (326); a plurality of brushes (312, 314, 316) including respective sets of conductive bristles (336, 338, 344), the sets of conductive bristles (336, 338, 344) brushing against respective insulated portions of the member (326); at least one motor (401) configured to i) move the part (326) relative to the brushes (312, 314, 316) and / or ii) move one or more of the brushes (312, 314, 316) relative to the part (326); and a control module configured to i) control the at least one motor (401) to follow a movement profile, and ii) during movement of the part (326) and / or the one or more brushes (312, 314, 316), detect a defect in the insulating material of the part (326) due to a short circuit between one or more of the conductive bristles (336, 338, 344) of the plurality of brushes (312, 314, 316) and an exposed conductive element of the part (326) at a location of the defect; characterized by , that: (i) the support for the part (326) is mounted on the frame (304) and the at least one motor (401) is mounted directly or indirectly on the frame (304); or (ii) the at least one motor (401) comprises a motor for moving at least one of the plurality of brushes (312, 314, 316) between a deployed state and a stowed state, and the at least one of the plurality of brushes (312, 314, 316) contacts the part (326) when in the deployed state and does not contact the part (326) when in the stowed state; or (iii) the plurality of brushes (312, 314, 316) comprise at least one straight brush (312, 314), at least one gamma brush (312, 314) and at least one 'U'-shaped brush (316). [3] The insulation testing system (200) of claim 2, wherein the support for the part (326) is implemented as a rotatable support plate (322) configured to rotate the part (326) with respect to the plurality of brushes (312, 314, 316). [4] The insulation testing system (200) of claim 2, wherein: the frame (304) comprises a plurality of rails (306); the plurality of brushes (312, 314, 316) are attached to the plurality of rails (306) via a plurality of brush holders (308); and the plurality of brush holders (308) are movable relative to the plurality of rails (306). [5] The insulation testing system (200) of claim 4, wherein the at least one motor (401) is configured to move at least one of the brush holders (308) along at least one of the plurality of rails (306). [6] Insulation testing system (200) according to claim 4, wherein: the plurality of rails (306) comprise a first rail and a second rail; the first rail is attached to a clamp and carries at least one of the brushes (312, 314, 316); the clamp is attached to the second rail and can be moved along it; and a portion of the clamp is rotatable relative to the second rail to transfer the at least one of the plurality of brushes (312, 314, 316) between a stowed state and a deployed state. [7] The insulation testing system (200) of claim 6, wherein the at least one motor (401) is configured to move the clamp relative to the second rail. [8] The insulation testing system (200) of claim 1, wherein: the part (326) is a stator; and the plurality of brushes (312, 314, 316) are configured to brush multiple sides of a crown end (330) and a welded end of the stator.

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