CN209992563U - Leakage current detection device - Google Patents
Leakage current detection device Download PDFInfo
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- CN209992563U CN209992563U CN201822269784.4U CN201822269784U CN209992563U CN 209992563 U CN209992563 U CN 209992563U CN 201822269784 U CN201822269784 U CN 201822269784U CN 209992563 U CN209992563 U CN 209992563U
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Abstract
The embodiment of the utility model discloses leakage current detection device, include: the transient suppression circuit comprises a secondary winding middle tap of an isolation transformer, a thermistor PTC, a leakage current sampling resistor R2, a regulating resistor R1, a bidirectional transient suppression tube TVS, a filter capacitor C1 and a bidirectional optocoupler U1, wherein the first end of the bidirectional transient suppression tube TVS is electrically connected with the secondary winding middle tap of the isolation transformer, and the bidirectional transient suppression tube TVS is connected with the thermistor in series and is grounded. The adjusting resistor R1 is connected in series with the current sampling resistor R2 and then connected in parallel with the bidirectional transient suppression tube TVS, the second end of the filter capacitor C1 is electrically connected with the second end of the current sampling resistor R2, the primary side of the bidirectional optocoupler U1 is connected in parallel with the filter capacitor C1, and the secondary side of the bidirectional optocoupler U1 generates a detection signal. The method has the advantages of low cost, simple scheme, few used devices, simple scheme and high reliability.
Description
Technical Field
The utility model relates to an elevator technical field especially relates to a leakage current detection device.
Background
On one hand, in many old elevators at present, the insulating performance is reduced due to the fact that a band-type brake coil is used for too long time, the coil is aged and the like, and the fault phenomenon that the coil leaks electricity to the ground PE can occur; when the leakage current does not reach the action current of the air switch of the band-type brake loop (generally 30mA, or the failure of the air switch), the air switch is controlled not to trip, and the elevator is further dragged to operate or slide, so that potential safety hazards are generated.
Fig. 1 is a schematic diagram of a prior art elevator band-type brake power supply circuit. Referring to fig. 1, a conventional band-type brake power supply circuit 100 includes a band-type brake power supply circuit 11, a freewheeling circuit 12, and a band-type brake coil 13. During normal operation, when leakage occurs to the earth PE at a certain position (such as M point) of the band-type brake coil 13 (when leakage occurs, the dotted line in the figure becomes a solid line), when the leakage current does not reach the action current of the control air switch of the band-type brake loop or when the control air switch fails and does not trip. The currents on 2 coils of the band-type brake coil are unbalanced, for example, the half cycle of the alternating current: the working mode of the L2 that only the half part of the coil at the M point has current can cause the contracting brake coil L1 and the contracting brake coil L2 to be asynchronous, namely, in one alternating current period, when the L1 works through two wave currents, only a part of the L2 works. When the elevator runs, the elevator drag brake is caused to run; when the elevator stops, the L2 does not pass through the follow current loop and flows current through the leakage point, so that the band-type brake opens a small gap to cause the elevator to run. Therefore, a detection circuit and a detection method capable of solving the above problems are needed, and since the existing detection method in the market is basically realized by detecting the current between the internal contracting brake coil and the ground through the hall sensor and converting the current into a voltage signal, the method is complex and has high cost.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a leakage current detection apparatus to provide a leakage current detection apparatus with lower cost and lower detection cost.
Correspondingly, the embodiment of the utility model provides a leakage current detection device, include: a thermistor PTC, a leakage current sampling resistor R2, a regulating resistor R1, a bidirectional transient suppression tube TVS, a filter capacitor C1 and a bidirectional optical coupler U1, wherein a first end of the bidirectional transient suppression tube TVS is electrically connected to a center tap of a secondary winding of the isolation transformer, a second end of the bidirectional transient suppression tube TVS is electrically connected to the first end of the thermistor PTC, a second end of the thermistor PTC is grounded, a first end of the regulating resistor RI is electrically connected to the first end of the bidirectional transient suppression tube TVS, a second end of the regulating resistor RI is electrically connected to the first end of the leakage current sampling resistor, a second end of the leakage current sampling resistor is electrically connected to the second end of the thermistor, a first end of the filter capacitor C1 is electrically connected to the first end of the current sampling resistor R2, and a second end of the filter capacitor C1 is electrically connected to the second end of the current sampling resistor R2, the primary side of the bidirectional optocoupler U1 is connected in parallel with the filter capacitor C1, and the secondary side of the bidirectional optocoupler U1 generates a detection signal.
Further, the leakage current detection device further includes:
and the power output control unit is electrically connected with the secondary side of the bidirectional optical coupler U1 and is used for controlling the on-off of a power supply according to a detection signal generated by the secondary side of the bidirectional optical coupler U1.
Further, the power output control unit includes:
the trigger level signal power supply is used for providing a high level signal for triggering the response of the singlechip;
the filtering unit comprises a resistor R3 and a capacitor, wherein a first end of the resistor R3 is electrically connected with the trigger level signal power supply, a second end of the resistor R3 is electrically connected with a first end of the capacitor, a second end of the capacitor is grounded, and a second end of the resistor R3 is electrically connected with an IO port of the single chip microcomputer;
the first end of the secondary side of the bidirectional optical coupler U1 is electrically connected with the second end of the resistor R3, and the second end of the secondary side of the bidirectional optical coupler U1 is electrically connected with the second end of the capacitor.
Further, the singlechip is an AT89C52 chip.
Further, the TVS of the bidirectional transient suppression tube is SMBJ16CA-E3/52 TVS.
Furthermore, the type of the bidirectional optical coupler U1 is K3010.
The embodiment of the utility model provides a leakage current detection device turns into voltage signal through sampling resistance with the leakage current, can pass through (detect) voltage signal, generates the corresponding detected signal of two-way opto-coupler. The problem that the elevator drags the brake to run or slides due to the fact that the leakage current of the band-type brake coil to the ground PE does not reach the action value of the air switch of the band-type brake loop can be detected by setting the adjusting resistor. Meanwhile, the problem that the control function of the elevator is abnormal due to abnormal reduction or fluctuation of output voltage caused by the fact that the output of the switching power supply of the integrated power supply is grounded due to circuit aging can be solved. Compared with the prior art, the embodiment of the utility model provides a leakage current detection device low cost, the scheme is simple, uses the device few, and the scheme is simple, and the reliability is high.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:
FIG. 1 is a schematic circuit diagram of a prior art band-type brake power supply;
fig. 2 is a schematic circuit diagram of a leakage current detection apparatus according to an embodiment of the present invention;
fig. 3 is a leakage current flow diagram of a leakage current detection apparatus according to a first embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a leakage current detection device according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
Example one
Fig. 2 is a schematic circuit diagram of a leakage current detection device according to an embodiment of the present invention. Referring to fig. 2, the leakage current detecting apparatus includes: a secondary winding center tap (which may also be a center tap of an output filter inductor of a non-isolation topology structure), a thermistor PTC, a leakage current sampling resistor R2, a regulating resistor R1, a bidirectional transient suppression tube TVS, a filter capacitor C1 and a bidirectional optocoupler U1, wherein a first end of the bidirectional transient suppression tube TVS is electrically connected to the secondary winding center tap of the isolation transformer, a second end of the bidirectional transient suppression tube TVS is electrically connected to the first end of the thermistor PTC, a second end of the thermistor PTC is grounded, a first end of the regulating resistor RI is electrically connected to the first end of the bidirectional transient suppression tube TVS, a second end of the regulating resistor RI is electrically connected to the first end of the leakage current sampling resistor, a second end of the leakage current sampling resistor is electrically connected to the second end of the thermistor, a first end of the filter capacitor C1 is electrically connected to the first end of the current sampling resistor R2, the second end of the filter capacitor C1 is electrically connected with the second end of the current sampling resistor R2, the primary side of the bidirectional optocoupler U1 is connected in parallel with the filter capacitor C1, and the secondary side of the bidirectional optocoupler U1 generates a detection signal.
A power supply circuit is shown in fig. 1, and as can be seen from fig. 1, the power supply circuit 200 includes an input ACDC conversion circuit 21, a main topology circuit 22, and the output leakage current detection protection circuit 23. The input ACDC conversion circuit 21 and the main topology circuit 22 work together to provide energy for a band-type brake (or a switching power supply load), wherein the main topology circuit 22 is drawn as a double-tube forward, and the power supply circuit can also be a power electronic basic DCDC conversion topology such as forward, flyback, phase shift bridge, LLC resonance, and the like.
One end of a point A in the output leakage current detection device is required to be connected to a middle tap of a secondary winding of the main topology 22 isolation transformer, the other end of the point A is connected with one end of the adjusting resistor R1 and one end of the bidirectional transient suppression tube TVS, the other end of the adjusting resistor R1 is connected with the sampling resistor R2, the other end of the sampling resistor R2 is connected with a point B, the sampling resistor R2 is connected with the filter capacitor C1 and the primary side of the bidirectional optocoupler U1 in parallel, the point B is connected with the other end of the bidirectional transient suppression tube TVS and one end of the thermistor PTC, and the other end of the thermistor PTC is connected with the ground PE. Wherein, the function of the thermistor PTC is to limit current when the output is short-circuited to the ground; the sampling resistor R2 is used for converting a leakage current signal into a voltage signal; the adjusting resistor R1 is used for adjusting the magnitude of the leakage current protection current; the bidirectional transient suppression tube TVS has the functions of preventing very high output voltage at the moment of leakage from being directly applied to the sampling resistor R1 and assisting in adjusting the magnitude of leakage current protection current; the filter capacitor C1 is used for filtering interference signals to prevent false operation; two-way opto-coupler U1's effect is the conversion and exports detected signal, and is exemplary, can two-way opto-coupler U1's secondary limit connects an pilot lamp in series, can detect when earth PE electric leakage, lights the suggestion staff through the pilot lamp and closes the power, avoids taking place danger.
Fig. 3 is a leakage current flow diagram of the leakage current detection device according to the first embodiment of the present invention, referring to fig. 2, when the output leaks to ground in normal operation, for example, the output + leaks to ground PE, a leakage current may form a loop through a middle tap of the secondary winding of the isolation transformer → DC + → PE → R2 → R1 → the output + the ground PE; the sampling resistor R2 converts leakage current into a voltage signal, due to the serial voltage division of the adjusting resistor R1 and the parallel shunting function of the TVS tube, when the leakage current reaches (or exceeds) a certain set value threshold, the voltage signal of the sampling resistor R2 enables the bidirectional optical coupler U1 to be switched on, at the moment, the leakage current signal is converted into a detection signal, the output control circuit U2 identifies the detection signal so as to switch off the output, and the leakage current protection function acts; when the leakage current is lower than the set value threshold, the voltage signal of the sampling resistor R2 is too low to cut off the bidirectional optocoupler U1, at the moment, the output control circuit U2 identifies a detection signal to enable the integrated power supply to continue normal output, and the leakage current protection function is reset.
Optionally, the leakage current protection threshold may be set and adjusted through the adjusting resistor R1, the sampling resistor R2, and the bidirectional transient suppression tube TVS, for example, if the resistance value of the adjusting resistor R1 is 3K, the resistance value of the sampling resistor R2 is 510 Ω, the model of the bidirectional transient suppression tube TVS is SMBJ16CA-E3/52, the model of the bidirectional optocoupler U1 is K3010, then the leakage current protection threshold is 3 mA; in this case, by changing the resistance of the regulating resistor R1 to 11k, the leakage current protection threshold will be increased to 15 mA.
The embodiment of the utility model provides a leakage current detection device turns into voltage signal through sampling resistance with the leakage current, can pass through voltage signal, generates the corresponding detected signal of two-way opto-coupler. The problem that the elevator drags the brake to run or slides due to the fact that the leakage current of the band-type brake coil to the ground PE does not reach the action value of the air switch of the band-type brake loop can be detected by setting the adjusting resistor. Meanwhile, the problem that the control function of the elevator is abnormal due to abnormal reduction or fluctuation of output voltage caused by the fact that the output of the switching power supply of the integrated power supply is grounded due to circuit aging can be solved. Compared with the prior art, the embodiment of the utility model provides a leakage current detection device low cost, the scheme is simple, uses the device few, and the scheme is simple, and the reliability is high.
Example two
Fig. 4 is a schematic circuit diagram of a leakage current detection device according to a second embodiment of the present invention. The present embodiment is optimized based on the above embodiments. Specifically, the leakage current detection device may further include: and the power output control unit is electrically connected with the secondary side of the bidirectional optical coupler U1 and is used for controlling the on-off of a power supply according to a detection signal generated by the secondary side of the bidirectional optical coupler U1.
When the leakage of the integrated power supply output to the ground PE is detected, a leakage detection signal is timely output to control the integrated power supply output, and when the integrated power supply brake output part leaks electricity, the elevator stops acting by controlling the integrated power supply output, so that the problem that the elevator is dragged to operate or rolls is solved; on the other hand, the problem that the control function of the elevator is abnormal due to abnormal reduction or fluctuation of output voltage caused by the fact that the ground leakage is caused by the output of the switching power supply due to the aging of a circuit of the switching power supply of the integrated power supply can be solved.
Therefore, in this embodiment, the leakage current detection apparatus may further include: and a power output control unit for controlling the power supply by the detection signal generated by the leakage current detection device provided in the first embodiment.
Illustratively, the power output control unit includes:
the trigger level signal power supply is used for providing a high level signal for triggering the response of the singlechip;
the filtering unit comprises a resistor R3 and a capacitor, wherein a first end of the resistor R3 is electrically connected with the trigger level signal power supply, a second end of the resistor R3 is electrically connected with a first end of the capacitor, a second end of the capacitor is grounded, and a second end of the resistor R3 is electrically connected with an IO port of the single chip microcomputer;
the first end of the secondary side of the bidirectional optical coupler U1 is electrically connected with the second end of the resistor R3, and the second end of the secondary side of the bidirectional optical coupler U1 is electrically connected with the second end of the capacitor.
Illustratively, the single chip microcomputer is an AT89C52 chip, and the trigger level signal power supply may be a 3.3V power supply, so that an IO interface of the single chip microcomputer can receive a high or low level signal triggering a corresponding action.
The following describes the operation of the power output control unit in the leakage current detection apparatus provided in this embodiment with reference to the operation of the power output control unit. When a detection signal is not generated on the secondary side of the bidirectional optocoupler U1, a loop cannot be formed between a trigger level signal power supply and the ground due to the existence of a capacitor. In fig. 4, the potential of the IO port is equal to the potential of the second end of the resistor R3, and a loop cannot be formed between the trigger level signal power supply and the ground, that is, the potential of the IO port is equal to the potential of the trigger level signal power supply. That is, the IO port receives a high level signal at this time, and the single chip microcomputer does not receive a trigger signal at this time. When the secondary side of the bidirectional optocoupler U1 generates a detection signal, namely, the connection between 3 and 4 in FIG. 4 is equivalent, and a trigger level signal power supply forms a loop with the ground through the resistors R3 and 4, and the point 3. Since R3 has a voltage dividing effect, the potential at IO is equal to the potential at the second end of the resistor R3, and the potential at the second end of the resistor R3 is 0. Therefore, the IO port receives the low level signal, and at the moment, the singlechip receives the low level trigger signal, and the power is conducted and controlled, and the integrated power supply is cut off, so that the elevator stops operating, and dangerous accidents are avoided.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (6)
1. A leakage current detection device, comprising: the isolation transformer comprises a secondary winding middle tap of the isolation transformer, a thermistor PTC, a leakage current sampling resistor R2, a regulating resistor R1, a bidirectional transient suppression tube TVS, a filter capacitor C1 and a bidirectional optical coupler U1, wherein a first end of the bidirectional transient suppression tube TVS is electrically connected with the secondary winding middle tap of the isolation transformer, a second end of the bidirectional transient suppression tube TVS is electrically connected with a first end of the thermistor PTC, a second end of the thermistor PTC is grounded, a first end of the regulating resistor R1 is electrically connected with a first end of the bidirectional transient suppression tube TVS, a second end of the regulating resistor R1 is electrically connected with a first end of the leakage current sampling resistor, a second end of the leakage current sampling resistor is electrically connected with a second end of the thermistor, a first end of the filter capacitor C1 is electrically connected with a first end of the current sampling resistor R2, and a second end of the filter capacitor C1 is electrically connected with a second end of the current sampling resistor R2, the primary side of the bidirectional optocoupler U1 is connected in parallel with the filter capacitor C1, and the secondary side of the bidirectional optocoupler U1 generates a detection signal.
2. The leakage current detection device according to claim 1, further comprising:
and the power output control unit is electrically connected with the secondary side of the bidirectional optical coupler U1 and is used for controlling the on-off of a power supply according to a detection signal generated by the secondary side of the bidirectional optical coupler U1.
3. The leakage current detection device according to claim 2, wherein the power supply output control unit includes:
the trigger level signal power supply is used for providing a high level signal for triggering the response of the singlechip;
the filtering unit comprises a resistor R3 and a capacitor, wherein a first end of the resistor R3 is electrically connected with the trigger level signal power supply, a second end of the resistor R3 is electrically connected with a first end of the capacitor, a second end of the capacitor is grounded, and a second end of the resistor R3 is electrically connected with an IO port of the single chip microcomputer;
the first end of the secondary side of the bidirectional optical coupler U1 is electrically connected with the second end of the resistor R3, and the second end of the secondary side of the bidirectional optical coupler U1 is electrically connected with the second end of the capacitor.
4. The leakage current detection device of claim 3, wherein the single chip microcomputer is an AT89C52 chip.
5. The leakage current detection device according to claim 1, wherein the bidirectional transient suppression tube TVS is an SMBJ16CA-E3/52 TVS.
6. The leakage current detection device according to claim 1, wherein the bidirectional optical coupler is U1 model K3010.
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| CN201822269784.4U CN209992563U (en) | 2018-12-29 | 2018-12-29 | Leakage current detection device |
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| CN201822269784.4U CN209992563U (en) | 2018-12-29 | 2018-12-29 | Leakage current detection device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109541287A (en) * | 2018-12-29 | 2019-03-29 | 天津康途科技有限公司 | A kind of leak current detection device |
| CN112582997A (en) * | 2020-11-02 | 2021-03-30 | 武汉华中数控股份有限公司 | Leakage suppression circuit and control method thereof |
-
2018
- 2018-12-29 CN CN201822269784.4U patent/CN209992563U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109541287A (en) * | 2018-12-29 | 2019-03-29 | 天津康途科技有限公司 | A kind of leak current detection device |
| CN112582997A (en) * | 2020-11-02 | 2021-03-30 | 武汉华中数控股份有限公司 | Leakage suppression circuit and control method thereof |
| CN112582997B (en) * | 2020-11-02 | 2023-03-10 | 武汉华中数控股份有限公司 | Electric leakage suppression circuit and control method thereof |
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