Split Insulated Input Post for an Electrical Measurement Tool

Abstract

A device for performing electrical measurements according to the present disclosure includes a first input post that is electrically conductive, a second input post that is electrically conductive, and an electrically insulating sleeve at least partially surrounding the first and second input posts. The sleeve includes a first rib extending longitudinally of the sleeve and a second rib extending longitudinally of the sleeve. The first rib and the second rib are configured to separate the first and second input posts.

Description

Technical Field

[0001] The present disclosure generally relates to electrical measurement tools, and more particularly to an electrical measurement tool that enables a circuit breaker device to become non-conductive or a warning device to issue a warning in response to a test lead connected to an input post that does not match the selected operating mode in order to reduce the risk of damage to the electrical measurement tool.

Background Art

[0002] Electrical measurement tools, such as digital multimeters, have been used to measure various different electrical characteristics, such as current, voltage, and resistance. A typical digital multimeter includes different input terminals to which electrical test leads can be connected to electrically connect the digital multimeter to an electrical circuit having the electrical characteristic to be measured. Specifically, a typical digital multimeter includes a first input terminal internally coupled to an electrical circuit arranged to measure a relatively large current, a second input terminal internally coupled to an electrical circuit arranged to measure a medium current and a relatively small current, a third input terminal internally coupled to a common potential, and a fourth input terminal internally coupled to an electrical circuit arranged to measure voltage and other electrical characteristics.

[0003] In addition, a typical digital multimeter includes a knob that can be rotated by a user to select one of several different operating modes of the digital multimeter, such as operating modes for different types of current and voltage measurements. If the user connects a test lead to an input terminal for current measurement with the knob rotated to a position corresponding to the operating mode for voltage measurement, there is a risk of a large current flowing through the digital multimeter. The large current can damage the device being tested and can blow the internal fuse of the digital multimeter. If the power supply voltage exceeds the fuse rating of the internal fuse of the digital multimeter, arcing, damage to the multimeter, and injury to the user can occur.

SUMMARY OF THE INVENTION

[0004] The present disclosure teaches a device including one or more split input terminals for use in current measurement that can reduce the risk of damage to the device. A controller coupled to the split input terminals receives a signal indicating the mode in which the device is operating and a signal indicating whether the input posts of the split input terminals, which indicates whether a test lead is inserted into the split input terminals, are electrically coupled to each other. The controller can place a circuit breaker device in a non-conductive state to protect internal components of the device, such as a fuse. Additionally or alternatively, the controller can cause a warning device to generate a warning to the user of the device, whereby the user can take corrective action before damage to the device occurs or before injury to the user occurs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

Figure 2F

Figure 2G

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 3E

Figure 3F

Figure 3G

Figure 3H

Figure 4

Figure 5

Figure 6A

Figure 6B

DETAILED DESCRIPTION OF THE INVENTION

[0006] An electrical measurement tool can be damaged when used to measure electrical characteristics using a test lead connected to an input terminal of the electrical measurement tool that is inappropriate based on the selected operating mode. For example, if a digital multimeter is operating in voltage measurement mode and is used to measure voltage using a test lead connected to an input terminal of the digital multimeter that is for current measurement, the internal fuse of the digital multimeter can be damaged.

[0007] In accordance with the present disclosure, damage to an electrical measurement tool can be prevented. The present disclosure teaches a split input terminal that enables an electrical measurement tool to determine whether a test lead is connected to the input terminal while the electrical measurement tool is operating in the selected operating mode. If the electrical measurement tool determines that a test lead is connected to the input terminal while the electrical measurement tool is operating in the selected operating mode, the electrical measurement tool places a circuit breaker device in a non-conductive state to prevent current flow through components that could be damaged by inappropriate operation of the electrical measurement tool. Additionally or alternatively, if the electrical measurement tool determines that a test lead is connected to the input terminal while the electrical measurement tool is operating in the selected operating mode, the electrical measurement tool causes a warning device to generate a warning so that an operator of the electrical measurement tool can take corrective action (e.g., connect the test lead to a different input terminal or change the operating mode of the electrical measurement tool) before the electrical measurement tool is used in a manner that could damage the electrical measurement tool.

[0008] FIG. 1 is a diagram of the appearance of a system or device 100 according to an embodiment described herein. In one or more implementations, device 100 is a digital multimeter. For example, the device can be similar in many relevant respects to the Model 17B+ Digital Multimeter available from Fluke Calibration, as modified by the present disclosure.

[0009] Device 100 includes a case 102 that encloses various components of device 100. A rotary knob 104 is provided at the front portion of case 102. The rotary knob 104 can be rotated such that the tip of the knob is positioned at one of a plurality of positions 106a - 106j at the front portion of case 102.

[0010] More specifically, while the rotary knob 104 is rotated to position 106a, device 100 is turned off and battery power is not supplied to various electrical components of device 100. While the rotary knob 104 is rotated to position 106b, device 100 operates in a mode where a relatively large alternating current (AC) voltage can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106c, device 100 operates in a mode where a relatively large direct current (DC) voltage can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106d, device 100 operates in a mode where a relatively small DC voltage can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106e, device 100 operates in a mode where resistance can be measured by the measurement circuit, or conduction can be checked by the measurement circuit, or a diode junction can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106f, device 100 operates in a mode where capacitance can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106g, device 100 operates in a mode where a relatively large AC or DC current can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106h, device 100 operates in a mode where a medium AC or DC current can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106i, device 100 operates in a mode where a relatively small AC or DC current can be measured by the measurement circuit. While the rotary knob 104 is rotated to position 106j, device 100 operates in a mode where temperature can be measured by the measurement circuit.

[0011] The case 102 has four concave portions 110 - 116 where four input terminals 118 - 124 are respectively disposed. The input terminal 118 is a split input terminal including an electrical insulation sleeve surrounding two input posts spaced apart from each other and electrically insulated. At least one of the input posts of the split input terminal 118 is electrically coupled to a part of a measurement circuit arranged to measure a relatively large AC or DC current. When the conductive connector of an electrical test lead is inserted into the insulation sleeve of the split input terminal 118, the conductive connector electrically couples the input posts of the split input terminal 118 to each other. The input terminal 120 is also a split input terminal having a configuration similar to that of the input terminal 118. At least one of the input posts of the split input terminal 120 is electrically coupled to a part of a measurement circuit arranged to measure medium and relatively small AC or DC currents. The input terminal 122 is a conventional input terminal including an electrical insulation sleeve and a single input post electrically coupled to a common potential or a reference potential. The input terminal 124 is also a conventional input terminal, including an electrical insulation sleeve and a single input post electrically coupled to various parts of a measurement circuit arranged to measure voltages of particularly different magnitudes.

[0012] In addition, the device 100 includes an indicator 126 used to generate a warning to the user of the device 100. For example, the indicator 126 includes a red light-emitting diode (LED) that blinks when the user inserts a test least into the split input terminal 118 or the split input terminal 120 while the rotary knob 104 is rotated to a position setting an operating mode other than the operating mode for current measurement. The device 100 also includes buttons 128a - 128e used by the user to supply an input for controlling the operation of the device 100. In addition, the device 100 includes a display device 130 that displays the results of electrical measurements, operation status information, and warnings. In one or more implementations, the display device 130 includes a liquid crystal device (LCD) display screen.

[0013] Figures 2A and 2B are perspective views of the electrical insulation sleeve 200 included in the split input terminals according to the embodiments described herein. For example, the electrical insulation sleeve 200 is included in each of the split input terminals 118 and 120 of the device 100 shown in FIG. 1. The electrical insulation sleeve 200 includes a substantially cylindrical body portion 200a and a flange portion 200b extending radially from the body portion 200a. Ribs 200c extend longitudinally of the electrical insulation sleeve 200 inside the body portion 200a and further project outwardly from the flange portion 200b. Similarly, ribs 200d extend longitudinally of the electrical insulation sleeve 200 inside the body portion 200a and further project outwardly from the flange portion 200b. The ribs 200c and 200d divide the compartment inside the body portion 200a into different portions 200e and 200f spaced apart from each other by the ribs 200c and 200d. Thus, when input posts are disposed in the portions 200e and 200f, the input posts are spaced apart from each other. Thus, the input posts are not electrically coupled to each other unless a test lead is inserted into the insulation sleeve 200, whereby the controller of the device 100 can determine when the test lead is inserted into the split input terminals including the input posts, as will be described in detail below.

[0014] As shown in FIGS. 2A and 2B, rib 200c includes two side surfaces 200c1 and 200c2, and rib 200d includes two side surfaces 200d1 and 200d2. In one or more embodiments, the side surfaces 200c1 and 200c2 of rib 200c are substantially perpendicular to the inner surface of the cylindrical body portion 200a, and the side surfaces 200d1 and 200d2 of rib 200d are substantially perpendicular to the inner surface of the cylindrical body portion 200a. In one or more embodiments, the side surfaces 200c1 and 200c2 of rib 200c form an angle of less than 90 degrees with the inner surface of the cylindrical body portion 200a, and the side surfaces 200d1 and 200d2 of rib 200d form an angle of less than 90 degrees with the inner surface of the cylindrical body portion 200a. The side surfaces 200c1 and 200c2 of rib 200c, and the side surfaces 200d1 and 200d2 of rib 200d hold the input posts of the split input terminals within the insulating sleeve 200 during the assembly of the device 100.

[0015] FIG. 2C is a perspective view of a pair of input posts 210 and 212 of a split input terminal according to an embodiment described herein. For example, the pair of input posts 210 and 212 are included in each of the split input terminals 118 and 120 of the device 100 shown in FIG. 1. Input post 210 includes a base portion 210a having an aperture 210b formed adjacent to a threaded portion formed in the base portion 210a, and a curved terminal portion 210c extending from the base portion 210a. Similarly, input post 212 includes a base portion 212a having an aperture 212b formed adjacent to a threaded portion formed in the base portion 212a, and a curved terminal portion 212c extending from the base portion 212a.

[0016] FIG. 2D is a perspective view of a partially assembled split input terminal in which a pair of input posts 210 and 212 shown in FIG. 2C are inserted into the electrical insulation sleeve 200 shown in FIGS. 2A and 2B. More specifically, input post 210 is inserted into compartment portion 200e inside body portion 200a, and input post 212 is inserted into compartment portion 200f inside body portion 200a. As seen in FIG. 2D, ribs 200c and 200d of electrical insulation sleeve 200 keep input posts 210 and 212 spaced apart from each other and electrically insulated. After input posts 210 and input post 212 are inserted into insulation sleeve 200, input post 210 contacts side surface 200c2 of rib 200c and side surface 200d2 of rib 200d, and input post 212 contacts side surface 200c1 of rib 200c and side surface 200d1 of rib 200d.

[0017] FIG. 2E and FIG. 2F are perspective views of a pair of electrical connectors 214 and 216 of a split input terminal according to an embodiment described herein. For example, each of the split input terminals 118 and 120 of the device 100 shown in FIG. 1 includes a pair of electrical connectors 214 and 216. The electrical connector 214 includes a connection portion 214a for electrically connecting the split input terminal to a component of the device 100, a contact portion 214b for electrically connecting the electrical connector 214 to the input post of the split input terminal, an aperture 214c formed in the contact portion 214b, a holding portion 214d extending from the contact portion 214b, and a holding portion 214e extending from the contact portion 214b. In one or more implementations, the contact portion 214b is flat, and the holding portions 214d and 214e are perpendicular to the contact portion 214b. Similarly, the electrical connector 216 includes a connection portion 216a for electrically connecting the split input terminal to a component of the device 100, a contact portion 216b for electrically connecting the electrical connector 216 to the input post of the split input terminal, an aperture 216c formed in the contact portion 216b, a holding portion 216d extending from the contact portion 216b, and a holding portion 216e extending from the contact portion 216b. In one or more implementations, the contact portion 216b is flat, and the holding portions 216d and 216e are perpendicular to the contact portion 216b.

[0018] FIG. 2G is a perspective view of a type of screw 218 used to attach a pair of electrical connectors 214 and 216 to a pair of input posts 210 and 212 included in the partially assembled split input terminal shown in FIG. 2D according to an embodiment described herein. The screw 218 includes a base portion 218a and a threaded portion 218b extending from the base portion 218a. The threaded portion 218b has a diameter smaller than the diameters of the apertures 210b and 212b of the pair of input posts 210 and 212 and smaller than the diameters of the apertures 214c and 216c of the pair of electrical connectors 214 and 216. The threaded portion 218b includes threads that mesh with the threads included in the threaded portions of the input posts 210 and 212.

[0019] FIG. 3A is a cross-sectional view of a portion of the case 102 of the device 100 shown in FIG. 1. FIG. 3B is an enlarged perspective view of a part of the portion of the case 102 shown in FIG. 3A. As shown in FIG. 3B, the concave portion 110 of the case 102 includes a substantially cylindrical side wall 110a. The end of the concave portion 110 of the case 102 includes an aperture 110b and a separating portion 110c that extends across the aperture case and divides the aperture 110b into two parts. The structure of the concave portion 112 is the same as that of the concave portion 110.

[0020] FIG. 3C is a cross-sectional view of a portion of the case 102 of the device 100 shown in FIG. 3A, with two partially assembled split input terminals inserted into the case 102. FIG. 3D is an enlarged perspective view of a part of the portion of the case 102 shown in FIG. 3C. More specifically, FIGS. 3C and 3D show the portion of the case 102 of the device 100 shown in FIG. 3A after two partially assembled split input terminals (each similar to the partially assembled split terminals shown in FIG. 2D) are inserted into the concave portions 110 and 112 from the front side of the case 102. As shown in FIGS. 3C and 3D, when the input terminals 210 and 212 are inserted into the concave portion 110, the separating portion 110c is disposed between the base portion 210a of the input post 210 and the base portion 212a of the input post 212.

[0021] FIG. 3E is a front view of a portion of the printed circuit board 220 according to the embodiment described herein. The printed circuit board 220 has apertures 220a - 220d formed therein corresponding to the concave portions of the case 102, respectively. More specifically, aperture 220a corresponds to the concave portion 116 of the case 102, aperture 220b corresponds to the concave portion 114 of the case 102, aperture 220c corresponds to the concave portion 112 of the case 102, and aperture 220d corresponds to the concave portion 110 of the case 102. The printed circuit board 220 has electrical conductors 222a - 222f formed thereon, each of which is coupled to a conductive trace coupled to an electrical component of the device 100.

[0022] FIG. 3F is a cross-sectional view of a portion of a partially assembled device 100 that includes a portion of the case 102 shown in FIG. 3C, where a portion of the printed circuit board 220 shown in FIG. 3E is disposed on top and two split input terminals 118 and 120 are coupled to the printed circuit board 220. More specifically, each of the electrical connectors of the split input terminals 118 and 120 is soldered to an electrical conductor formed on the printed circuit board 220. For example, the electrical connector 214 of the split input terminal 118 is soldered to the electrical conductor 222a, and the electrical connector 216 of the split input terminal 118 is soldered to the electrical conductor 222b. As shown in FIG. 3F, the recessed portions 118-124 of the case 102 are disposed in any one of the apertures 220a-220d formed in the printed circuit board 220.

[0023] FIG. 3G is an enlarged perspective view of a portion of the device 100 shown in FIG. 3F. The electrical connector 214 is coupled to the input post 210 using a screw 218, and the electrical connector 216 is coupled to the input post 212 using the screw 218. As shown in FIG. 3G, the holding portion 214d of the electrical connector 214 is disposed on a side surface of the electrical connector 214 between the electrical connector 214 and the electrical connector 216. Similarly, the holding portion 216d of the electrical connector 216 is disposed on a side surface of the electrical connector 216 between the electrical connector 214 and the electrical connector 216. The holding portion 214d of the electrical connector 214 and the holding portion 216d of the electrical connector 216 are offset from each other so as not to contact each other with the separation portion 110c therebetween. Also, the holding portion 214e of the electrical connector 214 and the holding portion 216e of the electrical connector 216 are provided on the side wall 110a of the recessed portion 110 of the case 102. The holding portions 214d and 214e of the electrical connector 214 prevent the electrical connector 214 from rotating while the screw 218 is rotated (e.g., using a screwdriver) to attach the electrical connector 214 to the input post 210. Similarly, the holding portions 216d and 216e of the electrical connector 216 prevent the electrical connector 216 from rotating while the screw 218 is rotated to attach the electrical connector 216 to the input post 212.

[0024] FIG. 3H is a cross-sectional view of a portion of device 100 along line 3H of FIG. 3F according to the embodiments described herein. As shown in FIG. 3H, the input posts of each of the split input terminals 118 and 120 are held spaced apart from each other by ribs (e.g., rib 200c) of the electrical insulating sleeve 200 and also by separating portions (e.g., separating portion 110c) of the recessed portions 110 and 112 of the case 102.

[0025] FIG. 4 is a simplified block diagram of device 100 according to the embodiments described herein. FIG. 4 shows split input terminal 118 and conventional common input terminal 122. For simplicity of explanation, FIG. 4 does not show split input terminal 120. However, split input terminal 120 is connected in a manner similar to the manner in which split input terminal 118 is connected, as described below.

[0026] As shown in FIG. 4, the input post 210 of the split input terminal 118 is electrically coupled (e.g., using wire and solder) to the first terminal of a pull-up resistor 224, and the pull-up resistor 224 has a second terminal electrically coupled to a power supply terminal V+ coupled to a logic high voltage output from a power supply (e.g., a battery). Additionally, the input post 210 of the split input terminal 118 is electrically coupled to a detection circuit 226, and the detection circuit 226 is electrically coupled to a controller 228. In one or more embodiments, the controller 228 includes a processor and a memory storing instructions that, when executed by the processor, cause the controller 228 to perform the functions of the controller 228 described herein. In one or more implementations, the detection circuit 226 outputs a signal having a logic high voltage while an electrical test lead is not inserted into the split input terminal 118 and outputs a signal having a logic low voltage while the electrical test lead is inserted into the split input terminal 118.

[0027] The other input post 212 of the split input terminal 118 is electrically coupled to a first terminal of a circuit breaker device 230 having a control terminal electrically coupled to the controller 228. The circuit breaker device 230 also has a second terminal electrically coupled to a first terminal of a fuse 232. The controller 228 supplies a control signal to the circuit breaker device 230 to control whether the circuit breaker device 230 is in a conductive state where the first terminal and the second terminal of the circuit breaker device 230 are electrically coupled to each other, or in a non-conductive state where the first terminal and the second terminal of the circuit breaker device 230 are not electrically coupled to each other. For example, when the control signal supplied to the circuit breaker device 230 by the controller 228 has a logic low value, the circuit breaker device 230 is in a non-conductive state, and when the control signal supplied to the circuit breaker device 230 by the controller 228 has a logic high value, the circuit breaker device 230 is in a conductive state. Examples of the circuit breaker device 230 include a relay, a contactor, and a reed switch. When the circuit breaker device 230 is in a non-conductive state, the input post 212 of the split input terminal 118 is not electrically coupled to the fuse 232, thereby preventing the fuse 232 from being damaged (e.g., blowing) when a large voltage at open circuit (VOC) exists between the split input terminal 118 and the common terminal 122. The second terminal of the fuse 232 is electrically coupled to a first terminal of a shunt resistor 234. The second terminal of the shunt resistor 234 is electrically coupled to the common input terminal 122.

[0028] In addition, a mode selection circuit 236 and an alarm circuit 238 are electrically coupled to the controller 228. In one or more implementations, the mode selection circuit 236 includes an encoder mechanically coupled to the rotary knob 104, generates one or more signals indicating an operating mode corresponding to the current position of the rotary knob 104, and supplies one or more signals indicating the operating mode to the controller 228. The operating mode corresponds to a specific operating mode selected using the rotary knob 104. The controller 228 uses one or more signals indicating the operating mode supplied by the mode selection circuit 236 and the signals supplied by the detection circuit 226 to make the circuit breaker device 230 conductive or non-conductive, and to determine whether to cause an alarm to be generated in the alarm circuit 238 or the display device 130.

[0029] In one or more embodiments, when the tip of the rotary knob 104 is positioned at the position 106a corresponding to the VAC operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0001" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106b corresponding to the VDC operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0010" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106c corresponding to the mV DC operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0011" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106d corresponding to the mV DC operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0100" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106e corresponding to the Ω operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0101" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106f corresponding to the capacitance operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0110" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106g corresponding to the A AC or DC operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "0111" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106h corresponding to the mA AC or DC operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "1000" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106i corresponding to the μA operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "1001" to the measurement circuit 118. When the tip of the rotary knob 104 is positioned at the position 106j corresponding to the °C operation mode, the mode selection circuit 236 supplies one or more signals indicating the code "1010" to the measurement circuit 118.

[0030] In one or more implementations, the alarm circuit 238 includes a sound-emitting device (e.g., a buzzer) that emits a sound when the controller 228 passes current through the sound-emitting device. In one or more implementations, the alarm circuit 238 includes a speaker, and the controller 228 causes the speaker to emit a voice warning that damage to the device 100 may occur if the device 100 is operating in its current operating mode because a test is inserted into a particular terminal (e.g., split input terminal 118 or 120). Additionally or alternatively, the alarm circuit 238 may include a light-emitting device (e.g., an LED) that emits light when the controller 228 passes current through the light-emitting device. In one or more implementations, a switch is electrically coupled between the alarm circuit 238 and a terminal coupled to a voltage supplied by a battery, and the controller 228 supplies a control signal that places the switch in a conductive or non-conductive state depending on the voltage level of the control signal. For example, if the control signal supplied by the controller 228 has a logic low voltage, the switch is in a non-conductive state, thereby preventing the voltage supplied by the battery from being supplied to the alarm circuit 228 and preventing an alarm or warning from being generated by the alarm circuit 238, and if the control signal supplied by the controller 228 has a logic high voltage, the switch is in a conductive state, thereby allowing the voltage supplied by the battery to be supplied to the alarm circuit 228 and allowing an alarm or warning to be generated by the alarm circuit 238.

[0031]

Table 1

[0032] Table 1 above shows an example of a logic table that can be used to determine whether the controller 228 stores to place the circuit breaker device 230 in a conductive or non-conductive state and to cause an alarm or warning to be generated by the alarm circuit 238 to warn the user that damage to the device 100 may occur if the device 100 operates in its current configuration (e.g., emits an alarm sound and / or lights up a warning light).

[0033] Figure 5 is a logic flow diagram showing the logic flow 300 of the device 100 according to the embodiments described herein. In one or more implementations, the logic flow 300 corresponds to the logic flow of the controller 228. The logic flow 300 starts at 302.

[0034] At 302, it is determined whether the current measurement operation mode has been selected. For example, the current measurement operation mode includes three operation modes corresponding to A, mA, or μA measurement, and the operation modes not for current measurement include operation modes corresponding to V ac, V dc, mV dc, capacitance, Ω, or °C. The controller 228 determines whether the current measurement operation mode has been selected based on one or more signals supplied by the mode selection circuit 236. If it is determined at 302 that the current measurement mode has been selected, the logic flow 300 proceeds to 304. If it is determined at 302 that the current measurement operation mode has not been selected, the logic flow 300 proceeds to 306.

[0035] At 304, the circuit breaker device is controlled to be in a conducting state, or the warning device is controlled to stop generating a warning. For example, the controller 228 supplies a control signal having a logic low voltage to turn on the circuit breaker device 230 to the circuit breaker device 230. Additionally or alternatively, the controller 228 supplies a control signal having a logic low voltage to stop the alarm circuit 238 from generating an alarm or warning to the alarm circuit 238. Additionally or alternatively, the controller 228 supplies a control signal to stop the display device 130 from generating a warning (e.g., stop displaying a warning message) to the display device 130. Then, the logic flow 300 returns to 302.

[0036] At 306, it is determined whether an electrical test lead is connected to the split input terminal. For example, the controller 228 determines whether the test lead is connected to the split input terminal 118 by determining whether the signal supplied by the detection circuit 226 has a logic high voltage or a logic low voltage. At 306, if it is determined that the test lead is connected (for example, the signal supplied by the detection circuit 226 has a logic low voltage), the logic flow 300 proceeds to 308. At 306, if it is determined that the test lead is not connected (for example, the signal supplied by the detection circuit 226 has a logic high voltage), the logic flow 300 proceeds to 310.

[0037] At 308, the circuit breaker device is controlled to be in a non-conductive state, or the warning device is controlled to generate a warning. For example, the controller 228 supplies a control signal having a logic high voltage to turn off the circuit breaker device 230 to the circuit breaker device 230. Additionally or alternatively, the controller 228 supplies a control signal having a logic high voltage to cause an alarm or warning to the alarm circuit 238 to the alarm circuit 238. Additionally or alternatively, the controller 228 supplies a control signal to cause a warning to the display device 130 by displaying a warning message (for example, "Warning! Damage may occur if the test lead is not removed from the A or mA μA input terminal or if the operating mode is not changed"). Then, the logic flow 300 returns to 302.

[0038] At 310, the circuit breaker device is controlled to be in a conducting state, or the warning device is controlled to stop generating a warning. For example, the controller 228 provides a control signal having a logic low voltage to the circuit breaker device 230, whereby the circuit breaker device 230 is in a conducting state. Additionally or alternatively, the controller 228 provides a control signal having a logic flow voltage to the alarm circuit 238 to stop the alarm circuit 238 from generating an alarm or a warning. Additionally or alternatively, the controller 228 supplies a control signal to the display device 130 to stop the display device 130 from generating a warning (e.g., stop displaying a warning message). Then, the logic flow 300 returns to 302.

[0039] FIGS. 6A and 6B are diagrams for explaining the use of the device 100 according to the embodiments described herein. FIG. 6A shows an example in which the device 100 is used to measure the current flowing through the circuit 402. The circuit 402 includes a voltage source 404, a switch 406, a node 408, a node 410, and a resistor 412 that are electrically coupled in series. The user connects the first connector of the test lead 414 to the common terminal 122 and the second connector of the test lead 414 to the node 410. Also, the user connects the first connector of the test lead 416 to the split input terminal 118 and the second connector of the test lead 416 to the node 408. In addition, the user rotates the rotary knob 104 so that the tip is at a position 106f corresponding to the current measurement operation mode (e.g., A). When the user closes the switch 406 of the circuit 402, the current flowing from the node 408 to the node 410 is measured by the measurement circuit, and the result of the current measurement is displayed by the display device 130.

[0040] FIG. 6A shows the correct operation of device 100. In other words, the user has rotated the rotary knob 104 to a position corresponding to a current measurement operation mode suitable for connecting a test lead to the split input terminal 118. Accordingly, device 100 does not turn off the circuit breaker device 130 and does not generate a warning via the display device 130 or the alarm circuit 238. However, if the user subsequently rotates the rotary knob 104 to a position not corresponding to the current measurement operation mode (e.g., V AC) while the test lead 416 is connected to the split input terminal 118 (or split input terminal 120), device 100 turns off the circuit breaker device 130 and generates a warning via the display device 130 or the alarm circuit 238 until the user disconnects the test lead 416 from the split input terminal 118 (or split input terminal 120) or rotates the rotary knob 104 to a position corresponding to the current measurement operation mode.

[0041] FIG. 6B shows an example in which device 100 is used to measure the voltage between two terminals of a voltage source 418. The user connects the first connector of test lead 414 to the common terminal 122 and the second connector of test lead 414 to one of the terminals of voltage source 418. Also, the user connects the first connector of test lead 416 to the input terminal 124 and the second connector of test lead 416 to the other terminal of voltage source 418. In addition, the user rotates the rotary knob 104 to a position 106a not corresponding to the current measurement operation mode (e.g., V AC).

[0042] FIG. 6B shows the correct operation of the device 100. In other words, the user is rotating the rotary knob 104 to a position that does not correspond to the current measurement operation mode suitable for connecting the test lead to the input terminal 124. Therefore, the device 100 does not turn the circuit breaker device 130 off and does not generate a warning via the display device 130 or the alarm circuit 238. However, if the user then disconnects the first connector of the test lead 416 from the input terminal 124 and then connects the first connector of the test lead 416 to the split input terminal 118 or 120 while the rotary knob 104 is in the position shown in FIG. 6B, this causes the circuit breaker device 130 to be turned off or a warning to be generated via the display device 130 or the alarm circuit 238 until the user disconnects the test lead 416 from the split input terminal 118 (or split input terminal 120) or rotates the rotary knob 104 to a position corresponding to the current measurement operation mode.

[0043] Combinations of the various embodiments described above can be provided to form further embodiments. Aspects of the embodiments can be used with concepts from various patents, applications, and publications, modified as necessary, to provide still further embodiments. The mode selection circuit 236 described above outputs a code indicating the position of the rotary knob 104 corresponding to the operation mode of the device 100, but the mode selector 104 may be implemented using a different type of selection mechanism. For example, the mode selector 104 can include a touch screen that outputs different codes corresponding to different operation modes of the device 100 based on selections made using the touch screen.

[0044] A device for performing electrical measurements according to the present disclosure can be summarized as including a first input post that is conductive, a second input post that is conductive, and a sleeve that is electrically insulating and at least partially surrounds the first input post and the second input post. The sleeve may include a first rib extending in the longitudinal direction of the sleeve and a second rib extending in the longitudinal direction of the sleeve. The first rib and the second rib may be configured to separate the first input post and the second input post.

[0045] The device may be a digital multimeter, and the first input post, the second input post, and the sleeve may be included in input terminals for current measurement.

[0046] The device may further include a case. The case can include a portion extending across an aperture formed within the case. The first input post and the second input post may extend through an aperture formed within the case, and the portion of the case that extends across the aperture formed within the case is disposed between the first input post and the second input post.

[0047] The first input post may contact the first surface of the first rib and the first surface of the second rib, and the second input post may contact the second surface of the first rib and the second surface of the second rib.

[0048] The device may further include a circuit board, a first electrical connector electrically coupled to the first input post and a first electrical conductor on the circuit board, and a second electrical connector electrically coupled to the second input post and a second electrical conductor on the circuit board. The first electrical connector may be coupled to the first input post by a screw, and the second electrical connector may be coupled to the second input post by a screw. The first electrical connector may be coupled to the first electrical conductor by soldering, and the second electrical connector may be coupled to the second electrical conductor by soldering.

[0049] The device may further include a case including a first input post, a second input post, and a concave portion in which a sleeve is at least partially disposed therein, and a circuit board including an aperture in which the concave portion of the case can be disposed therein.

[0050] The device may further include a first electrical connector electrically coupled to the first input post, a second electrical connector electrically coupled to the second input post, and a case including a concave portion in which the first input post, the second input post, and the sleeve are at least partially disposed therein. The first electrical connector and the second electrical connector may each include a contact portion, a first holding portion extending from the contact portion, and a second holding portion extending from the contact portion. The contact portion and the first holding portion of the first electrical connector may be disposed at the first input post, and the second holding portion of the first electrical connector may be disposed on a side wall of the concave portion of the case. The contact portion and the first holding portion of the second electrical connector may be disposed at the second input post, and the second holding portion of the second electrical connector may be disposed on a side wall of the concave portion of the case.

[0051] The device may further include a mode selection circuit that outputs at least one signal indicating at least one mode in which the device operates, a detection circuit that outputs at least one signal indicating whether a first input post is electrically coupled to a second input post, and a controller that outputs at least one control signal based on the at least one signal output by the mode selection circuit and the at least one signal output by the detection circuit. The device can further include a circuit breaker device that receives the at least one control signal output by the controller. While at least one signal output by the mode selection circuit indicates a first mode in which the device operates and at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post, the at least one control signal can turn the circuit breaker device to a non-conductive state. The at least one control signal can turn the circuit breaker device to a conductive state while at least one signal output by the mode selection circuit indicates a second mode in which the device operates and at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post. The device can further include a warning device that receives the at least one control signal output by the controller. The at least one control signal can cause the warning device to generate a warning while at least one signal output by the mode selection circuit indicates a first mode in which the device operates and at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post. The at least one control signal can stop the warning device from generating a warning while at least one signal output by the mode selection circuit indicates a second mode in which the device operates and at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post.

[0052] A system for performing electrical measurements according to the present disclosure includes a split input terminal including a first input post, a second input post, and a sleeve that is electrically insulating and at least partially surrounds the first input post and the second input post, the sleeve including a pair of ribs extending in the longitudinal direction of the sleeve for separating the first input post from the second input post; and a controller coupled to the split input terminal and configured to control a circuit breaker device or a warning device based on a device operation mode related to a status of electrical connectivity between the first input post and the second input post.

[0053] The controller can control the circuit breaker device to be in a non-conductive state or control the warning device to generate a warning while the device operation mode is in a first mode and the status of electrical connectivity is a status where the first input post is electrically coupled to the second input post. The controller can control the circuit breaker device to be in a conductive state or control the warning device to stop generating a warning while the device operation mode is in a second mode and the status of electrical connectivity is a status where the first input post is electrically coupled to the second input post. The controller can control the circuit breaker device to be in a conductive state or control the warning device to stop generating a warning while the status of the electrical connection is a status where the first input post is not electrically coupled to the second input post.

[0054] The system can further include a mode selection circuit that outputs at least one signal indicating the device operation mode to the controller, and a detection circuit that outputs at least one signal indicating the status of the electrical connection between the first input post and the second input post to the controller.

[0055] The warning device may be at least one of a light-emitting device that emits light, a sound-emitting device that emits sound, and a display device that displays a message.

[0056] A method for operating a digital multimeter device to reduce the risk of damaging the digital multimeter device includes receiving at least one signal indicating the mode in which the digital multimeter device is operating, receiving at least one signal indicating whether a first input post of a split input terminal is electrically coupled to a second input post of the split input terminal, and based on at least one signal indicating the mode in which the digital multimeter device is operating and at least one signal indicating whether the first input post is electrically coupled to the second input post, putting a circuit breaker device in a non-conductive state or causing a warning device to generate a warning.

[0057] Putting the circuit breaker device in a non-conductive state or causing the warning device to generate a warning may include putting the circuit breaker device in a non-conductive state or causing the warning device to generate a warning while at least one signal indicating the mode in which the digital multimeter is operating indicates a first mode and at least one signal indicating whether the first input post is electrically coupled to the second input post indicates that the first input post is electrically coupled to the second input post. The method may further include allowing the circuit breaker device to remain in a conductive state or stopping the warning device from generating a warning while at least one signal indicating the mode in which the digital multimeter device is operating indicates a second mode different from the first mode and at least one signal indicating whether the first input post is electrically coupled to the second input post indicates that the first input post is electrically coupled to the second input post.

[0058] The method may further include allowing the circuit breaker device to remain in a conductive state or stopping the warning device from generating a warning while at least one signal indicating whether the first input post is electrically coupled to the second input post indicates that the first input post is not electrically coupled to the second input post.

[0059] Putting the circuit breaker device in a non-conductive state or causing a warning to be generated in the warning device may include putting the circuit breaker device in a non-conductive state and causing a warning to be generated in the warning device.

[0060] The step of causing a warning to be generated in the warning device may include at least one of causing light to be emitted by a light-emitting device, causing sound to be emitted by a sound-emitting device, or causing a message to be displayed on a display device.

[0061] In view of the above "Embodiments of the Invention", these changes and other changes can be made to the embodiments. Generally, in the following "Claims", the terms used should not be construed as limiting the "Claims" to the specific embodiments disclosed in the specification and the "Claims", but should be construed as including all possible embodiments along the entire scope of equivalents given by such "Claims". Therefore, the "Claims" are not limited by the disclosure of this specification.

Claims

1. A device for performing an electrical measurement, the device comprising: a first input post that is conductive; a second input post that is conductive; a sleeve that is electrically insulating and at least partially surrounds the first input post and the second input post; the sleeve having a first rib extending in the longitudinal direction of the sleeve and a second rib extending in the longitudinal direction of the sleeve; the first rib and the second rib being configured to insulate the second input post from the first input post when an electrical test lead is not inserted into the sleeve; the first input post and the second input post being configured to be electrically coupled when an electrical test lead is inserted into the sleeve.

2. The device is a digital multimeter, the first input post, the second input post, and the sleeve being included in an input terminal for current measurement, the device according to claim 1.

3. further comprising a case, the case including a portion extending across an aperture formed in the case, the first input post and the second input post extending through the aperture formed in the case, and the portion of the case extending across the aperture formed in the case being disposed between the first input post and the second input post, the device according to claim 1 or 2.

4. a circuit board; a first electrical connector electrically coupled to the first input post and a first electrical conductor on the circuit board; a second electrical connector electrically coupled to the second input post and a second electrical conductor on the circuit board; the first electrical connector being coupled to the first input post by a screw, and the second electrical connector being coupled to the second input post by a screw; the first electrical connector being coupled to the first electrical conductor by solder, and the second electrical connector being coupled to the second electrical conductor by solder, the device according to any one of claims 1 to 3.

5. a case including a recess in which the first input post, the second input post, and the sleeve are at least partially disposed inside; The device according to any one of claims 1 to 4, further comprising a circuit board including an aperture in which the concave portion of the case is disposed inside.

6. A first electrical connector electrically coupled to the first input post; A second electrical connector electrically coupled to the second input post; A case including a concave portion in which the first input post, the second input post, and the sleeve are at least partially disposed inside, The first electrical connector and the second electrical connector each have a contact portion, a first holding portion extending from the contact portion, and a second holding portion extending from the contact portion. The contact portion and the first holding portion of the first electrical connector are disposed at the first input post, and the second holding portion of the first electrical connector is disposed on a side wall of the concave portion of the case. The contact portion and the first holding portion of the second electrical connector are disposed at the second input post, and the second holding portion of the second electrical connector is disposed on the side wall of the concave portion of the case. The device according to any one of claims 1 to 5.

7. A mode selection circuit that outputs at least one signal indicating at least one mode in which the device operates; A detection circuit that outputs at least one signal indicating whether the first input post is electrically coupled to the second input post; A controller that outputs at least one control signal based on the at least one signal output by the mode selection circuit and the at least one signal output by the detection circuit. The device according to any one of claims 1 to 6.

8. Further comprising a circuit breaker device that receives the at least one control signal output by the controller, While the at least one signal output by the mode selection circuit indicates a first mode in which the device operates and the at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post, the at least one control signal renders the circuit breaker device non-conductive. The device according to claim 7, wherein at least one signal output by the mode selection circuit indicates a second mode in which the device operates, and while at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post, the at least one control signal places the circuit breaker device in a conductive state.

9. further comprising a warning device that receives the at least one control signal output by the controller, wherein at least one signal output by the mode selection circuit indicates a first mode in which the device operates, and while at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post, the at least one control signal causes the warning device to generate a warning, The device according to claim 7 or 8, wherein at least one signal output by the mode selection circuit indicates a second mode in which the device operates, and while at least one signal output by the detection circuit indicates that the first input post is electrically coupled to the second input post, the at least one control signal causes the warning device to stop generating the warning.

10. A system for performing an electrical measurement, the system comprising a split input terminal including a first input post, a second input post, and a sleeve that is electrically insulating and at least partially surrounds the first and second input posts, the sleeve including a pair of ribs extending in a longitudinal direction of the sleeve to insulate the second input post from the first input post when an electrical test lead is not inserted into the sleeve, and the first and second input posts being configured to be electrically coupled when an electrical test lead is inserted into the sleeve; a controller coupled to the split input terminal and configured to control a circuit breaker device or a warning device based on a device operation mode related to a status of electrical connectivity between the first input post and the second input post.

11. The controller controls the circuit breaker device to be in a non-conductive state or controls the warning device to generate a warning while the device operation mode is the first mode and the status of the electrical connectivity is such that the first input post is electrically coupled to the second input post. The system according to claim 10, wherein the controller controls the circuit breaker device to be in a conductive state or controls the warning device to stop generating the warning while the device operation mode is the second mode and the status of the electrical connectivity is such that the first input post is electrically coupled to the second input post.

12. The system according to claim 11, wherein the controller controls the circuit breaker device to be in a conductive state or controls the warning device to stop generating the warning while the status of the electrical connectivity is such that the first input post is not electrically coupled to the second input post.

13. A mode selection circuit that outputs at least one signal indicating the device operation mode to the controller; The system according to any one of claims 10 to 12, further comprising a detection circuit that outputs at least one signal indicating the status of the electrical connectivity between the first input post and the second input post to the controller.

14. A method of operating a digital multimeter device to reduce the risk of damaging the digital multimeter device, the method comprising: Receiving at least one signal indicating the mode in which the digital multimeter device is operating; Receiving at least one signal indicating whether a first input post of a split input terminal is electrically coupled to a second input post of the split input terminal, wherein the split input terminal is electrically insulating and includes a sleeve at least partially surrounding the first input post and the second input post, the sleeve having a first rib extending in a longitudinal direction of the sleeve and a second rib extending in the longitudinal direction of the sleeve, the first rib and the second rib being configured to insulate the second input post from the first input post when an electrical test lead is not inserted into the sleeve, and the first input post and the second input post being configured to be electrically coupled when the electrical test lead is inserted into the sleeve, and Based on the at least one signal indicating the mode in which the digital multimeter device is operating and the at least one signal indicating whether the first input post is electrically coupled to the second input post, either putting a circuit breaker device in a non-conductive state or causing a warning device to generate a warning, the method comprising.

15. Putting the circuit breaker device in a non-conductive state or causing the warning device to generate the warning includes putting the circuit breaker device in a non-conductive state or causing the warning device to generate the warning while the at least one signal indicating the mode in which the digital multimeter device is operating indicates a first mode and the at least one signal indicating whether the first input post is electrically coupled to the second input post indicates that the first input post is electrically coupled to the second input post, The method further includes, while the at least one signal indicating the mode in which the digital multimeter device is operating indicates a second mode different from the first mode and the at least one signal indicating whether the first input post is electrically coupled to the second input post indicates that the first input post is electrically coupled to the second input post, either putting the circuit breaker device in a conductive state or stopping the warning device from generating the warning, the method according to claim 14.

16. The method of claim 15, further comprising, while the at least one signal indicating whether the first input post is electrically coupled to the second input post indicates that the first input post is not electrically coupled to the second input post, causing the circuit breaker device to be in the conducting state or stopping causing the warning to occur at the warning device. **Claim 17** The method according to any one of claims 14 to 16, wherein causing the circuit breaker device to be in a non-conducting state or causing the warning to occur at the warning device includes causing the circuit breaker device to be in a non-conducting state and causing a warning to occur at the warning device.

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