CN220605551U - Secondary side protection grounding device of voltage transformer - Google Patents
Secondary side protection grounding device of voltage transformer Download PDFInfo
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- CN220605551U CN220605551U CN202320685487.6U CN202320685487U CN220605551U CN 220605551 U CN220605551 U CN 220605551U CN 202320685487 U CN202320685487 U CN 202320685487U CN 220605551 U CN220605551 U CN 220605551U
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- overvoltage
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- grounding device
- voltage transformer
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- 230000001012 protector Effects 0.000 claims description 23
- 238000009413 insulation Methods 0.000 abstract description 15
- 230000009286 beneficial effect Effects 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000001419 dependent effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Abstract
The utility model discloses a secondary side protection grounding device of a voltage transformer, which comprises a piezoresistor, an overvoltage relay and a contactor, wherein the piezoresistor is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE, coils of the overvoltage relay are connected in parallel at two ends of the piezoresistor, contacts of the overvoltage relay and coils of the contactor are connected in series in a power supply loop of the contactor, and a normally open contact of the contactor is connected in series between the secondary side terminal N of the voltage transformer and the grounding terminal PE. The utility model is used for protecting and grounding the transformer low-voltage side incoming line PT secondary circuit so as to meet the insulation requirement and the grounding protection requirement.
Description
Technical Field
The utility model belongs to the technical field of electric power, and particularly relates to a secondary side protection grounding device of a voltage transformer.
Background
In a 10kV power supply system on site, a low-voltage side (0.4 kV) incoming line breaker is disconnected, zero-line insulation resistance values of upper and lower ports of the breaker are measured to be 0.3 megaohm, and the insulation resistance requirement is not met.
Fig. 1 is a schematic diagram of the secondary side grounding of a low-voltage side incoming line PT of a conventional transformer, which is determined according to the fact that the neutral point of the low-voltage side (0.4 kV) of a 10kV power supply system in China is directly grounded, and the secondary side of the low-voltage side incoming line PT is grounded, and when an insulation resistance value is measured, an upper port is grounded from the PT secondary side, and a lower port is conducted after being grounded from an N-row neutral point, so that the insulation resistance value does not meet design requirements.
According to the judgment, the PT secondary side N and the PE line are disconnected, the upper opening insulation value and the lower opening insulation value reach the design requirement, and the correctness of the problem is verified. However, in the working state, the PT secondary side N and the PE cannot be disconnected, and the secondary side is protected from overvoltage by grounding, so a PT secondary side protection grounding device is required to realize both functions.
Disclosure of Invention
The utility model aims to overcome the defects of the prior art and provides a secondary side protection grounding device of a voltage transformer, which is used for protecting and grounding a secondary loop of a transformer low-voltage side incoming wire PT so as to meet the insulation requirement and the grounding protection requirement.
The technical scheme of the utility model is realized as follows: the utility model discloses a secondary side protection grounding device of a voltage transformer, which comprises an overvoltage protection grounding device, wherein the overvoltage protection grounding device is connected in series between a secondary side terminal N and a grounding terminal PE of the voltage transformer.
Further, when the voltage across the overvoltage protection ground device does not exceed the overvoltage threshold value, the overvoltage protection ground device is in an open state, and when the voltage across the overvoltage protection ground device exceeds the overvoltage threshold value, the overvoltage protection ground device is in a short state.
Further, the overvoltage protection grounding device is a piezoresistor.
Further, the secondary side protection grounding device of the voltage transformer further comprises an overvoltage protector and a contactor, wherein the input end of the overvoltage protector is connected with two ends of an overvoltage protection grounding device, the output end of the overvoltage protector is connected with the contactor, when the input voltage of the overvoltage protector exceeds an overvoltage threshold value, the contactor controlled by the overvoltage protector is conducted, and a normally open contact of the contactor is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE.
Further, the overvoltage protector adopts an overvoltage relay, a coil of the overvoltage relay is connected with an overvoltage protection grounding device in parallel, and a movable contact of the overvoltage relay and a coil of the contactor are connected in series in a power supply loop of the contactor.
Further, the normally closed contact of the contactor and the overvoltage protection grounding device are connected in series between the secondary side terminal N of the voltage transformer and the grounding terminal PE.
Further, one end of a normally closed contact of the contactor is connected with a secondary side terminal N of the voltage transformer, the other end of the normally closed contact of the contactor is connected with one end of an overvoltage protection grounding device, and the other end of the overvoltage protection grounding device is connected with a grounding terminal PE.
Further, the secondary side protection grounding device of the voltage transformer further comprises an overvoltage relay, a coil of the overvoltage relay is connected with an overvoltage protection grounding device in parallel, and a normally open contact of the overvoltage relay is connected between a secondary side terminal N of the voltage transformer and a grounding terminal PE in series.
Further, the action time of the overvoltage protection grounding device is smaller than that of the overvoltage relay.
The utility model has at least the following beneficial effects: the secondary side protection grounding device of the voltage transformer can realize the secondary side protection grounding of the incoming line PT of the low-voltage side of the transformer, meets the insulation requirement under the normal condition and the grounding protection requirement under the overvoltage condition, is beneficial to prolonging the service life of the low-voltage frame circuit breaker and ensures the power transmission safety.
The secondary side protection grounding device of the voltage transformer ensures the secondary side protection grounding of the low-voltage side incoming line PT, is beneficial to prolonging the service life of the low-voltage frame circuit breaker and ensures the power transmission safety. Meanwhile, the standby loop is arranged, so that the reliability is high, and the power supply reliability is ensured. And the protection and grounding of the secondary side of the low-voltage side incoming line PT are comprehensively guaranteed, meanwhile, the power supply reliability is improved, and the later operation and maintenance cost is saved.
Drawings
In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of secondary side grounding of a low-voltage side incoming line PT of a conventional transformer;
fig. 2 is a schematic diagram illustrating secondary side protection grounding of a low-voltage side incoming line PT of a transformer according to an embodiment of the present utility model;
fig. 3 is a schematic diagram of a secondary side protection grounding device of a voltage transformer according to an embodiment of the present utility model.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
In order to realize protection and grounding of the low-voltage side incoming line PT secondary side of the transformer and meet insulation requirements under normal conditions and grounding protection requirements under overvoltage conditions, the applicant designs that the PT secondary side N and the PE line are disconnected in normal times and connected in overvoltage protection, and the transformer low-voltage side incoming line PT secondary side protection and grounding is used for protecting and grounding of the low-voltage side incoming line PT secondary side of the transformer so as to meet the design requirements of zero-row upper port and lower port insulation of a low-voltage incoming line breaker and ensure safety.
Example 1
Referring to fig. 2 and 3, an embodiment of the present utility model provides a secondary side protection grounding device of a voltage transformer, which includes an overvoltage protection grounding device connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE.
When the voltage of the two ends of the overvoltage protection grounding device does not exceed the overvoltage threshold value, the overvoltage protection grounding device is in an open circuit state or a high-resistance state, and when the voltage of the two ends of the overvoltage protection grounding device exceeds the overvoltage threshold value, the overvoltage protection grounding device is in a short circuit state or a conducting state.
Further, the overvoltage protection grounding device adopts, but is not limited to, a piezoresistor RV. The varistor RV is normally in an off state, and is turned on to discharge to the ground when in overvoltage, so that the functional requirement can be met.
The varistor RV is similar to an open circuit under normal conditions, and acts similar to a short circuit during overvoltage, namely, the N is connected with PE to discharge, so that the secondary side is protected. The circuit is a normal operation circuit (circuit 1).
Under the fault condition of an overvoltage protection grounding device such as a piezoresistor RV, another loop is needed to realize the connection of N and PE wires, and the overvoltage protection grounding device can be realized by an overvoltage relay KV or an overvoltage protector matched with a contactor. Under the overvoltage condition, the piezoresistor RV is not broken down, and then the overvoltage relay KV is grounded in an action mode or the overvoltage protector controls the contactor to realize connection of the N line and the PE line.
Example two
Referring to fig. 2 and 3, on the basis of the first embodiment, the secondary side protection grounding device of the voltage transformer of the present embodiment further includes an overvoltage relay KV and a contactor KM, where a coil of the overvoltage relay KV is connected in parallel with the overvoltage protection grounding device, a moving contact of the overvoltage relay KV and a coil of the contactor KM are connected in series in a power supply loop of the contactor KM, and a normally open contact of the contactor KM is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE.
Further, the normally closed contact of the contactor KM and the overvoltage protection grounding device are connected in series between the secondary side terminal N and the grounding terminal PE of the voltage transformer.
Further, one end of a normally closed contact of the contactor KM is connected with a secondary side terminal N of the voltage transformer, the other end of the normally closed contact of the contactor KM is connected with one end of an overvoltage protection grounding device, and the other end of the overvoltage protection grounding device is connected with a grounding terminal PE.
The varistor RV and the overvoltage relay KV need to be matched in time, the action time of the varistor RV is nS level, and the action time of the overvoltage relay KV is mS level, so that the varistor RV and the overvoltage relay KV can be matched with each other.
The overvoltage relay loop (namely loop 2) is a standby loop of the loop 1, and when the piezoresistor RV effectively acts, the voltage at two ends of the relay is 0 and does not act like a short circuit. When the varistor RV does not act, the overvoltage relay KV acts as a standby grounding loop according to the overvoltage setting action. The relay operation time is in mS level, so that the piezoresistor RV operates preferentially and can be matched with each other.
When the overvoltage relay KV acts, the movable contact is closed, and the contactor KM coil is electrified to conduct attraction. Under normal conditions, the contact KM 1 of the contactor is normally closed, and the contact 2 is normally open. The coil is electrically attracted, the contact 1 is disconnected, and the contact 2 is closed. The discharge is grounded through loop 2.
The voltage dependent resistor RV effectively acts when the voltage dependent resistor RV does not act, the voltage dependent relay KV and the contactor KM act, two loops are guaranteed to be standby, protection and grounding during overvoltage are achieved, and the voltage dependent resistor RV is disconnected to meet the insulation level during normal operation. Meanwhile, after the device is installed, the zero-row insulation values of the upper port and the lower port are measured for rechecking, and the secondary side protection grounding device of the voltage transformer can solve the problem that the insulation level of the zero-row upper port and the lower port of the low-voltage inlet circuit breaker cannot reach the standard due to secondary side grounding of the low-voltage inlet wire PT of the transformer.
Example III
On the basis of the first embodiment, the secondary side protection grounding device of the voltage transformer further comprises an overvoltage relay KV, a coil of the overvoltage relay KV is connected with an overvoltage protection grounding device in parallel, and a normally open contact of the overvoltage relay KV is connected between a secondary side terminal N of the voltage transformer and a grounding terminal PE in series.
Example IV
On the basis of the first embodiment, the secondary side protection grounding device of the voltage transformer further comprises an overvoltage protector and a contactor KM, wherein the input end of the overvoltage protector is connected with two ends of an overvoltage protection grounding device, the output end of the overvoltage protector is connected with the contactor, when the input voltage of the overvoltage protector exceeds an overvoltage threshold value, the contactor controlled by the overvoltage protector is conducted, and a normally open contact of the contactor is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE.
The overvoltage protector is used for detecting the voltage at two ends of the overvoltage protection grounding device and controlling the coil of the contactor KM to be electrified or powered off.
The overvoltage protector is used for detecting voltages at two ends of the overvoltage protection grounding device, comparing the detected voltages with a set value, and controlling a coil of the contactor KM to be electrified when the detected voltages are larger than the set value, namely the voltages at the two ends of the overvoltage protection grounding device are overvoltage.
The overvoltage protector comprises a voltage detection circuit, a comparison module and a contactor control circuit, wherein the comparison module can adopt a hardware comparison circuit, and of course, a software comparison scheme, such as a program in an MCU, can also be adopted for comparison.
Further, the normally closed contact of the contactor KM and the overvoltage protection grounding device are connected in series between the secondary side terminal N and the grounding terminal PE of the voltage transformer.
Further, one end of a normally closed contact of the contactor KM is connected with a secondary side terminal N of the voltage transformer, the other end of the normally closed contact of the contactor KM is connected with one end of an overvoltage protection grounding device, and the other end of the overvoltage protection grounding device is connected with a grounding terminal PE.
The secondary side protection grounding device of the voltage transformer can realize the secondary side protection grounding of the incoming line PT of the low-voltage side of the transformer, meets the insulation requirement under the normal condition and the grounding protection requirement under the overvoltage condition, is beneficial to prolonging the service life of the low-voltage frame circuit breaker and ensures the power transmission safety.
The secondary side protection grounding device of the voltage transformer ensures the secondary side protection grounding of the low-voltage side incoming line PT, is beneficial to prolonging the service life of the low-voltage frame circuit breaker and ensures the power transmission safety. Meanwhile, the standby loop is arranged, so that the reliability is high, and the power supply reliability is ensured. And the protection and grounding of the secondary side of the low-voltage side incoming line PT are comprehensively guaranteed, meanwhile, the power supply reliability is improved, and the later operation and maintenance cost is saved.
The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.
Claims (8)
1. The utility model provides a voltage transformer secondary side protection earthing device which characterized in that: the overvoltage protection grounding device is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE, and is in an open circuit state when the voltage at two ends of the overvoltage protection grounding device does not exceed an overvoltage threshold value, and is in a short circuit state when the voltage at two ends of the overvoltage protection grounding device exceeds the overvoltage threshold value.
2. The secondary side protection grounding device of a voltage transformer as claimed in claim 1, wherein: the overvoltage protection grounding device is a piezoresistor.
3. The secondary side protection grounding device of a voltage transformer as claimed in claim 1, wherein: the overvoltage protector is characterized by further comprising an overvoltage protector and a contactor, wherein the input end of the overvoltage protector is connected with two ends of an overvoltage protection grounding device, the output end of the overvoltage protector is connected with the contactor, when the input voltage of the overvoltage protector exceeds an overvoltage threshold value, the contactor controlled by the overvoltage protector is conducted, and a normally open contact of the contactor is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE.
4. The secondary side protection grounding device of a voltage transformer as claimed in claim 3, wherein: the overvoltage protector adopts an overvoltage relay, a coil of the overvoltage relay is connected with an overvoltage protection grounding device in parallel, and a movable contact of the overvoltage relay and a coil of the contactor are connected in series in a power supply loop of the contactor.
5. The secondary side protection grounding device of a voltage transformer as claimed in claim 3 or 4, wherein: the normally closed contact of the contactor and the overvoltage protection grounding device are connected in series between the secondary side terminal N of the voltage transformer and the grounding terminal PE.
6. The secondary side protection grounding device of a voltage transformer as claimed in claim 5, wherein: one end of a normally closed contact of the contactor is connected with a secondary side terminal N of the voltage transformer, the other end of the normally closed contact of the contactor is connected with one end of an overvoltage protection grounding device, and the other end of the overvoltage protection grounding device is connected with a grounding terminal PE.
7. The secondary side protection grounding device of a voltage transformer as claimed in claim 1, wherein: the overvoltage relay is characterized by further comprising an overvoltage relay, a coil of the overvoltage relay is connected with an overvoltage protection grounding device in parallel, and a normally open contact of the overvoltage relay is connected in series between a secondary side terminal N of the voltage transformer and a grounding terminal PE.
8. The secondary side protection grounding device of a voltage transformer as claimed in claim 4 or 7, wherein: the action time of the overvoltage protection grounding device is smaller than that of the overvoltage relay.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320685487.6U CN220605551U (en) | 2023-03-31 | 2023-03-31 | Secondary side protection grounding device of voltage transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320685487.6U CN220605551U (en) | 2023-03-31 | 2023-03-31 | Secondary side protection grounding device of voltage transformer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220605551U true CN220605551U (en) | 2024-03-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320685487.6U Active CN220605551U (en) | 2023-03-31 | 2023-03-31 | Secondary side protection grounding device of voltage transformer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220605551U (en) |
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2023
- 2023-03-31 CN CN202320685487.6U patent/CN220605551U/en active Active
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