Motor insulation on-line detection system

Abstract

The invention relates to the technical field of high-voltage motor detection, and discloses a motor insulation on-line detection system, which comprises an insulation detection host and a high-voltage isolation unit, and is characterized in that the insulation detection host is connected with a three-phase winding of a motor through the high-voltage isolation unit; the insulation detection host comprises a main control module, and the main control module is connected with an adjustable high-voltage module and a resistance measurement and disconnection detection module; the high-voltage isolation unit comprises three paths of high-voltage relays for high-voltage isolation, the three paths of high-voltage relays are respectively connected in series with a current-limiting resistor, the control ends of the three paths of high-voltage relays are connected with the main control module, and the input end of any path of high-voltage relay is connected with the measurement voltage output end of the adjustable high-voltage module; the input ends of the other two paths of high-voltage relays are connected with the ground, and the high-voltage relay connected with the adjustable high-voltage module is connected with a reactor L in series; according to the invention, the safety, accuracy and comprehensiveness of detection can be effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of high-voltage motor detection, and specifically to an online motor insulation detection system. Background Art

[0002] High-voltage motors are widely used in various industrial fields. According to the high-voltage motor operation management regulations, insulation measurements should be carried out regularly on standby motors; insulation measurements should be carried out before power is supplied to motors after maintenance, newly installed motors, and motors with power outages of more than seven days; and the insulation of motors of major auxiliary equipment should be measured before regular switching of operation.

[0003] At present, motor insulation measurement is mainly carried out in two forms, manual megger and insulation resistance tester. Among them, manual megger faces problems such as complex process, low work efficiency and high safety risk. Insulation resistance tester has the following three problems:

[0004] First, the detector measures the winding-to-ground resistance by directly connecting to the high-voltage circuit. This method easily introduces the high voltage of the high-voltage circuit into the insulation resistance detector, which poses a greater safety hazard to equipment and personnel.

[0005] Second, in order to reduce the impact of high-voltage circuits on equipment, current insulation resistance testers use larger resistors (tens of megohms) to connect to the high-voltage circuit for voltage division, which results in excessive voltage division of the resistor. The voltage actually injected into the motor is too low after voltage division, which does not meet the insulation resistance measurement voltage requirements, resulting in inaccurate insulation resistance measurement.

[0006] Third, the current insulation resistance tester cannot identify the "false" high insulation resistance caused by broken motor windings, and its functions are not comprehensive. Summary of the invention

[0007] The purpose of this application is to provide an online motor insulation detection system that can effectively improve the safety, accuracy and comprehensiveness of detection.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] An online motor insulation detection system of the present invention comprises an insulation detection host and a high-voltage isolation unit, wherein the insulation detection host is connected to the three-phase winding of the motor through the high-voltage isolation unit;

[0010] The insulation detection host comprises a main control module for information collection and coordinated control, the main control module is connected to an adjustable high-voltage module for outputting an adjustable DC measurement voltage, and a resistance measurement and disconnection detection module for insulation resistance measurement and disconnection detection of a motor high-voltage circuit;

[0011] The high-voltage isolation unit includes three high-voltage relays for high-voltage isolation, the three high-voltage relays are respectively connected in series with a current-limiting resistor, the control ends of the three high-voltage relays are connected to the main control module, the input end of any one of the high-voltage relays is connected to the measurement voltage output end of the adjustable high-voltage module, the input ends of the other two high-voltage relays are connected to the ground, and the high-voltage relay connected to the adjustable high-voltage module is connected in series with an inductor L.

[0012] Furthermore, the current limiting resistor is a small resistance current limiting resistor.

[0013] Furthermore, the main control module is connected to a measuring locking module for collecting auxiliary contact status signals of a high-voltage circuit breaker, the measuring locking module is connected to a high-voltage circuit breaker, and the high-voltage circuit breaker is connected to a three-phase winding of a motor.

[0014] Furthermore, the resistance measurement and disconnection detection module includes at least two sets of parallel sampling circuits, and any set of the sampling circuits includes a sampling resistor, and the sampling resistor is connected to a sampling relay.

[0015] Furthermore, the main control module is connected to a human-computer interaction module for inputting instructions and displaying data.

[0016] Furthermore, the main control module is connected to a communication module for realizing data interaction with the control terminal.

[0017] An online detection method for motor insulation, including an insulation resistance measurement method and a winding break detection method;

[0018] Insulation resistance measurement methods include:

[0019] According to the resistance value of the current limiting resistor and the measurement requirement that the voltage output to the motor winding coil is a standard voltage of 2500V, the adjustable high-voltage module is controlled by the main control module to adjust the output DC measurement voltage;

[0020] The main control module controls the high-voltage relay connected to the reactor L to be closed, the reactor L is in a short-circuit state, and a DC measurement voltage is applied to the motor;

[0021] The insulation resistance value of the motor is detected by the resistance measurement and wire break detection module and fed back to the main control module of the insulation detection host;

[0022] If during the measurement process, the motor generates AC voltage, the reactor L will be in a high impedance state, limiting the high voltage access to the insulation detection host;

[0023] Winding break detection methods include:

[0024] The main control module controls the high-voltage relay connected to the reactor L and the high-voltage relay connected to any phase circuit of the motor to close, and the high-voltage relay connected to the reactor L and the high-voltage relay connected to the remaining phase circuit of the motor to close, and the resistance value between the corresponding closed paths is measured by the resistance measurement and disconnection detection module;

[0025] The main control module determines whether the motor winding is broken based on the resistance value.

[0026] Furthermore, the main control module controls the adjustable high-voltage module to adjust the output DC measurement voltage according to the following formula: (Vdc-2500) / R=2500 / Rm, and Vdc2 / (R+Rm)≤P, wherein Vdc is the DC measurement voltage, R is the resistance value of the current limiting resistor, Rm is the resistance value of the motor insulation resistance, and P is the output power of the adjustable high-voltage module.

[0027] Furthermore, before measuring the insulation resistance, the circuit breaker opening and closing state is determined by collecting the state signal fed back to the main control module by the auxiliary contact of the circuit breaker;

[0028] When the circuit breaker is in the closed state, the insulation resistance detection function is locked by the main control module, the adjustable high-voltage module is controlled to stop outputting high voltage, and the connection between the high-voltage isolation unit and the motor test circuit is disconnected to achieve effective isolation;

[0029] When the circuit breaker is in the disconnected state, the insulation resistance measurement function is unlocked through the main control module, the adjustable high-voltage module is controlled to trigger the output DC measurement voltage, the high-voltage isolation unit is connected to the motor test circuit, and the insulation resistance measurement and winding break detection are performed;

[0030] During the measurement, the main control module controls the measurement locking module to output a locking signal to lock the control circuit of the high-voltage circuit breaker, so that the high-voltage circuit breaker cannot be closed, thereby preventing the motor from being powered on during the measurement.

[0031] After the measurement is completed, the lock is released and the main control module controls the high-voltage circuit breaker circuit to be connected.

[0032] Compared with the prior art, the beneficial effects of this application are:

[0033] In actual applications, the system is powered by an external power supply connected to the power module, and the main control module is used to control the adjustable high-voltage module to output a DC measurement voltage according to demand, effectively avoiding the problem that the voltage actually injected into the motor is too low after being divided, and thus does not meet the insulation resistance measurement voltage requirement; the motor winding is isolated from the adjustable high-voltage module used to output the measurement voltage through a high-voltage relay. During the insulation resistance measurement process, since the adjustable high-voltage module outputs a DC measurement voltage, the inductor L connected in series to the test circuit at the output end of the adjustable high-voltage module is in a short-circuit state. When the AC is generated when the motor is running, the inductor L is in a high-impedance state, which effectively avoids the AC high voltage generated by the motor operation from being introduced into the insulation detection host, posing a safety hazard to equipment and personnel while achieving safe and accurate detection of the insulation resistance; the two high-voltage relays connected to the ground are closed in sequence, and the resistance value of each phase winding of the motor is detected in sequence through the resistance measurement and disconnection detection module to determine whether the motor winding is disconnected, and then identify the "false" high insulation resistance caused by the motor winding disconnection; the present application can effectively improve the safety, accuracy and comprehensiveness of the detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the implementation methods of the present application, the drawings required for use in the implementation methods will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a schematic diagram of the system structure of this application;

[0036] Figure 2 is a circuit schematic diagram of the high voltage isolation unit of the present application;

[0037] Figure 3 is the insulation resistance measurement circuit schematic diagram of the present application;

[0038] Figure 4 This is a circuit schematic diagram of the winding break detection of the present application. DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0040] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show the layers related to the present invention rather than being drawn according to the number, shape and size of the layers in actual implementation. In actual implementation, the type, quantity and proportion of each layer may be changed arbitrarily, and the layer layout may also be more complicated.

[0041] In the following description, numerous details are discussed to provide a more thorough explanation of embodiments of the present invention; however, it is apparent to one skilled in the art that embodiments of the present invention may be practiced without these specific details.

[0042] See also Figures 1 to 4 , an online motor insulation detection system, comprising an insulation detection host and a high-voltage isolation unit, wherein the insulation detection host is connected to the three-phase winding of the motor through the high-voltage isolation unit;

[0043] The insulation detection host comprises a main control module for information collection and coordinated control, the main control module is connected to an adjustable high-voltage module for outputting an adjustable DC measurement voltage, and a resistance measurement and disconnection detection module for insulation resistance measurement and disconnection detection of a motor high-voltage circuit;

[0044] The high-voltage isolation unit includes three high-voltage relays for high-voltage isolation, the three high-voltage relays are respectively connected in series with a current-limiting resistor, the control ends of the three high-voltage relays are connected to the main control module, the input end of any one of the high-voltage relays is connected to the measurement voltage output end of the adjustable high-voltage module, the input ends of the other two high-voltage relays are connected to the ground, and the high-voltage relay connected to the adjustable high-voltage module is connected in series with an inductor L.

[0045] In actual applications, the system is powered by an external power supply connected to the power module, and the main control module is used to control the adjustable high-voltage module to output a DC measurement voltage according to demand, effectively avoiding the problem that the voltage actually injected into the motor is too low after being divided, and thus does not meet the insulation resistance measurement voltage requirement; the motor winding is isolated from the adjustable high-voltage module used to output the measurement voltage through a high-voltage relay. During the insulation resistance measurement process, since the adjustable high-voltage module outputs a DC measurement voltage, the inductor L connected in series to the test circuit at the output end of the adjustable high-voltage module is in a short-circuit state. When the AC is generated when the motor is running, the inductor L is in a high-impedance state, which effectively avoids the AC high voltage generated by the motor operation from being introduced into the insulation detection host, posing a safety hazard to equipment and personnel while achieving safe and accurate detection of the insulation resistance; the two high-voltage relays connected to the ground are closed in sequence, and the resistance value of each phase winding of the motor is detected in sequence through the resistance measurement and disconnection detection module to determine whether the motor winding is disconnected, and then identify the "false" high insulation resistance caused by the motor winding disconnection; the present application can effectively improve the safety, accuracy and comprehensiveness of the detection.

[0046] See also Figure 2 The current limiting resistor is a small resistance current limiting resistor. The use of a small resistance current limiting resistor can avoid excessive voltage division in the high-voltage circuit causing the actual voltage injected into the motor to be too low, thereby affecting the accuracy of insulation resistance measurement.

[0047] See also Figure 1 and Figure 2 The main control module is connected to a measurement locking module for collecting the status signal of the auxiliary contact of the high-voltage circuit breaker, and the measurement locking module is connected to the high-voltage circuit breaker, and the high-voltage circuit breaker is connected to the three-phase winding of the motor. The main control module is connected to collect the status signal of the high-voltage circuit breaker, which further avoids equipment damage and personnel injury caused by high-voltage power transmission of the motor during the measurement process.

[0048] See also Figure 3 and Figure 4 The resistance measurement and disconnection detection module includes at least two sets of parallel sampling circuits, and any set of the sampling circuits includes a sampling resistor, and the sampling resistor is connected to a sampling relay. More than two sets of measurement data are obtained through at least two sets of parallel sampling circuits, and the detection results are obtained based on the analysis of multiple sets of data to meet the accuracy requirements for measuring the insulation resistance of the motor.

[0049] See also Figure 1 The main control module is connected to a human-computer interaction module for inputting instructions and displaying data.

[0050] See also Figure 1 The main control module is connected to a communication module for realizing data interaction with the control terminal.

[0051] See also Figures 1 to 4 , an online detection method for motor insulation, including an insulation resistance measurement method and a winding break detection method;

[0052] Insulation resistance measurement methods include:

[0053] According to the resistance value of the current limiting resistor and the measurement requirement that the voltage output to the motor winding coil is a standard voltage of 2500V, the adjustable high-voltage module is controlled by the main control module to adjust the output DC measurement voltage; to avoid the problem that the voltage actually injected into the motor is too low after being divided, thereby failing to meet the insulation resistance measurement voltage requirement;

[0054] The main control module controls the high-voltage relay connected to the reactor L to be closed, the reactor L is in a short-circuit state, and a DC measurement voltage is applied to the motor;

[0055] The insulation resistance value of the motor is detected by the resistance measurement and wire break detection module and fed back to the main control module of the insulation detection host;

[0056] If during the measurement process, the motor generates AC voltage, the reactor L will be in a high impedance state, limiting the high voltage from being connected to the insulation detection host. The conductive characteristics of the reactor L can effectively prevent the AC high voltage generated by the motor from being introduced into the insulation detection host, which could pose a safety hazard to equipment and personnel.

[0057] Winding break detection methods include:

[0058] The main control module controls the high-voltage relay connected to the reactor L and the high-voltage relay connected to any phase circuit of the motor to close, and the high-voltage relay connected to the reactor L and the high-voltage relay connected to the remaining phase circuit of the motor to close, and the resistance value between the corresponding closed paths is measured by the resistance measurement and disconnection detection module;

[0059] The main control module determines whether the motor winding is broken based on the resistance value, and then identifies the "false" high insulation resistance caused by the motor winding break.

[0060] Since the three-phase windings A, B, and C of the motor are connected together, the DC measurement voltage output by the insulation detection host is connected to any phase circuit of the motor high-voltage circuit to achieve insulation measurement to ground. This solution selects the A phase circuit. The insulation detection host resistance measurement and wire break detection module realizes the measurement of the insulation resistance value of the motor.

[0061] For high-voltage motors with star connection, the insulation detection host controls the high-voltage isolation unit to close the high-voltage relays connected to the A and B phases and A and C phases of the motor's high-voltage circuit in turn. The resistance measurement and wire break detection module of the insulation detection host measures the resistance values ​​between phases A and B and between phases A and C respectively, and feeds the measured resistance values ​​back to the main control module. The main control module determines whether the high-voltage motor winding is broken based on the resistance value, and then identifies the "false" high insulation resistance caused by the broken wire of the motor winding.

[0062] See also Figures 1 to 3 , the adjustable high-voltage module is controlled by the main control module to adjust the output DC measurement voltage according to the following formula: (Vdc-2500) / R=2500 / Rm, and Vdc2 / (R+Rm)≤P, where Vdc is the DC measurement voltage, R is the resistance value of the current limiting resistor, Rm is the resistance value of the motor insulation resistance, and P is the output power of the adjustable high-voltage module. The resistance value of the current limiting resistor is 500k ohms.

[0063] See also Figure 1 , before measuring the insulation resistance, including judging the circuit breaker opening and closing state by collecting the state signal fed back to the main control module by the auxiliary contact of the circuit breaker;

[0064] When the circuit breaker is in the closed state, the insulation resistance detection function is locked by the main control module, the adjustable high-voltage module is controlled to stop outputting high voltage, and the connection between the high-voltage isolation unit and the motor test circuit is disconnected to achieve effective isolation;

[0065] When the circuit breaker is in the disconnected state, the insulation resistance measurement function is unlocked through the main control module, the adjustable high-voltage module is controlled to trigger the output DC measurement voltage, the high-voltage isolation unit is connected to the motor test circuit, and the insulation resistance measurement and winding break detection are performed;

[0066] During the measurement, the main control module controls the measurement locking module to output a locking signal to lock the control circuit of the high-voltage circuit breaker, so that the high-voltage circuit breaker cannot be closed, thereby preventing the motor from being powered on during the measurement.

[0067] After the measurement is completed, the lock is released and the main control module controls the high-voltage circuit breaker circuit to be connected.

[0068] In the above-mentioned embodiments, although the present invention has been described in conjunction with the specific embodiments of the present invention, many replacements, modifications and variations of these embodiments will be apparent to those skilled in the art according to the foregoing description. The embodiments of the present invention are intended to cover all such replacements, modifications and variations falling within the broad scope of the appended claims.

[0069] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A motor insulation online detection system, characterized in that: It includes an insulation detection host and a high-voltage isolation unit, wherein the insulation detection host is connected to the three-phase winding of the motor through the high-voltage isolation unit; The insulation detection host comprises a main control module for information collection and coordinated control, the main control module is connected to an adjustable high-voltage module for outputting an adjustable DC measurement voltage, and a resistance measurement and disconnection detection module for insulation resistance measurement and disconnection detection of a motor high-voltage circuit; The high-voltage isolation unit includes three high-voltage relays for high-voltage isolation, the three high-voltage relays are respectively connected in series with a current-limiting resistor, the control ends of the three high-voltage relays are connected to the main control module, the input end of any one of the high-voltage relays is connected to the measurement voltage output end of the adjustable high-voltage module, the input ends of the other two high-voltage relays are connected to the ground, and the high-voltage relay connected to the adjustable high-voltage module is connected in series with an inductor L.

2. The motor insulation online detection system according to claim 1, characterized in that: The current limiting resistor is a small resistance current limiting resistor.

3. The motor insulation online detection system according to claim 1, characterized in that: The main control module is connected to a measuring and locking module for collecting auxiliary contact status signals of a high-voltage circuit breaker, the measuring and locking module is connected to a high-voltage circuit breaker, and the high-voltage circuit breaker is connected to a three-phase winding of a motor.

4. The motor insulation online detection system according to claim 1, characterized in that: The resistance measurement and disconnection detection module includes at least two sets of parallel sampling circuits, and any set of the sampling circuits includes a sampling resistor, and the sampling resistor is connected to a sampling relay.

5. The motor insulation online detection system according to claim 1, characterized in that: The main control module is connected to a human-computer interaction module for inputting instructions and displaying data.

6. The motor insulation online detection system according to claim 1, characterized in that: The main control module is connected to a communication module for realizing data interaction with a control terminal.

7. A method for online detection of motor insulation, characterized in that: Including insulation resistance measurement method and winding break detection method; Insulation resistance measurement methods include: According to the resistance value of the current limiting resistor and the measurement requirement that the voltage output to the motor winding coil is a standard voltage of 2500V, the adjustable high-voltage module is controlled by the main control module to adjust the output DC measurement voltage; The main control module controls the high-voltage relay connected to the reactor L to be closed, the reactor L is in a short-circuit state, and a DC measurement voltage is applied to the motor; The insulation resistance value of the motor is detected by the resistance measurement and wire break detection module and fed back to the main control module of the insulation detection host; If during the measurement, the motor generates AC voltage, the reactor L will be in a high impedance state, limiting the high voltage access to the insulation detection host; Winding break detection methods include: The main control module controls the high-voltage relay connected to the reactor L and the high-voltage relay connected to any phase circuit of the motor to close, and the high-voltage relay connected to the reactor L and the high-voltage relay connected to the remaining phase circuit of the motor to close, and the resistance value between the corresponding closed paths is measured by the resistance measurement and disconnection detection module; The main control module determines whether the motor winding is broken based on the resistance value.

8. The method for online detection of motor insulation according to claim 1, characterized in that: The adjustable high-voltage module is controlled by the main control module to adjust the output DC measurement voltage according to the following formula: (Vdc-2500) / R=2500 / Rm, and Vdc2 / (R+Rm)≤P, where Vdc is the DC measurement voltage, R is the resistance value of the current limiting resistor, Rm is the resistance value of the motor insulation resistance, and P is the output power of the adjustable high-voltage module.

9. The method for online detection of motor insulation according to claim 1, characterized in that: Before measuring the insulation resistance, the circuit breaker opening and closing status is determined by collecting the status signal fed back to the main control module by the auxiliary contact of the circuit breaker; When the circuit breaker is in the closed state, the insulation resistance detection function is locked by the main control module, the adjustable high-voltage module is controlled to stop outputting high voltage, and the connection between the high-voltage isolation unit and the motor test circuit is disconnected to achieve effective isolation; When the circuit breaker is in the disconnected state, the insulation resistance measurement function is unlocked through the main control module, the adjustable high-voltage module is controlled to trigger the output DC measurement voltage, the high-voltage isolation unit is connected to the motor test circuit, and the insulation resistance measurement and winding break detection are performed; During the measurement, the main control module controls the measurement locking module to output a locking signal to lock the control circuit of the high-voltage circuit breaker, so that the high-voltage circuit breaker cannot be closed, thereby preventing the motor from being powered on during the measurement. After the measurement is completed, the lock is released and the main control module controls the high-voltage circuit breaker circuit to be connected.

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