CN203811749U - Single-phase ground fault monitoring device for non-grounded system - Google Patents
Single-phase ground fault monitoring device for non-grounded system Download PDFInfo
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- CN203811749U CN203811749U CN201420159472.7U CN201420159472U CN203811749U CN 203811749 U CN203811749 U CN 203811749U CN 201420159472 U CN201420159472 U CN 201420159472U CN 203811749 U CN203811749 U CN 203811749U
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- 238000012806 monitoring device Methods 0.000 title claims abstract description 14
- 230000007935 neutral effect Effects 0.000 claims description 15
- 238000012544 monitoring process Methods 0.000 abstract description 3
- 230000001629 suppression Effects 0.000 abstract 5
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
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Abstract
The utility model relates to a single-phase ground fault monitoring device for a non-grounded system, and belongs to the field of fault monitoring of power systems. The single-phase ground fault monitoring device includes a single-phase voltage transformer, a primary side fuse, a secondary side fuse, a parallel suppression resistor, an over-voltage relay and a low voltage relay. A primary side of the single-phase voltage transformer is connected through the primary side fuse to any and only one of A, B and C phases, while the other end is grounded; a secondary side of the single-phase voltage transformer is connected via the secondary side fuse to one end of the parallel suppression resistor, and the other end is connected to the other end of the parallel suppression resistor and grounded; the over-voltage relay is connected to the two ends of the parallel suppression resistor; and the low voltage relay is connected to the two ends of the parallel suppression resistor. The single-phase ground fault monitoring device for the non-grounded system is simple in structure and low in cost; and through the use of a single phase for voltage determination, the single-phase ground fault monitoring device is affected neither by the capacitance and current sizes of the system nor by the unbalanced current of a zero-sequence current filter.
Description
Technical field
The utility model relates to a kind of isolated neutral system singlephase earth fault monitoring device, belongs to the malfunction monitoring field of electric system.
Background technology
In electric system, having many distributions is isolated neutral system, there is singlephase earth fault in isolated neutral system time, because the electric current of trouble spot is very little, and line voltage between three-phase still keeps symmetrical, power supply on load does not affect, therefore, all allow in the ordinary course of things to continue operation 1～2 hour, and needn't trip immediately.But fault phase voltage-to-ground reduces when isolated neutral system generation singlephase earth fault, other two phase-to-ground voltage raises 1.73 times, for preventing that fault from further expanding, should send in time signal, so that operations staff takes measures.
Current existing isolated neutral system singlephase earth fault monitoring has two classes.
One class is that the residual voltage occurring on system busbar while utilizing isolated neutral system generation single-phase earthing is monitored, its schematic diagram as shown in Figure 1, the voltage transformer (VT) TV installing on system busbar is the voltage transformer (VT) of a three-phase five-limb, its secondary side open-delta reactive system residual voltage 3U0, over voltage relay KV0 two ends are connected to residual voltage 3U0.The method can be monitored out the system failure, but can only send the non-selectivity anticipating signal of system earth, can not judge generation Earth Phase, the voltage transformer (VT) of three-phase five-limb has the three-phase three winding voltage mutual inductors of 5 magnetic posts simultaneously, and required expense is high more than single-phase potential transformer.
Another kind of is that while utilizing isolated neutral system generation single-phase earthing, the zero-sequence current feature large compared with non-fault line on faulty line realizes; its schematic diagram as shown in Figure 2; monitor all outlet zero-sequence currents; although the method can be monitored the circuit that is out of order in theory; but owing to being subject to the impact of zero-sequence current filtrator out-of-balance current, in the time that the capacitance current capacitance current less or protected circuit of system is larger, cannot make accurate judgment.
Summary of the invention
The utility model provides a kind of isolated neutral system singlephase earth fault monitoring device, less economical and be subject to zero-sequence current filtrator out-of-balance current and be subject to the deficiency of line capacitance current affects for overcoming prior art.
The technical solution of the utility model is: a kind of isolated neutral system singlephase earth fault monitoring device, comprises single-phase potential transformer 1, primary side fuse 2, secondary side fuse 3, resistance 4, over voltage relay 5, the under-voltage replay 6 of suppressing in parallel; Wherein single-phase potential transformer 1 primary side is connected to arbitrary phase in mutually of A phase, B phase, C and is only connect a phase, other end ground connection by primary side fuse 2; Single-phase potential transformer 1 secondary side one end is connected to one end that suppresses resistance 4 in parallel by secondary side fuse 3, and the other end is connected to the other end ground connection of suppressing resistance 4 in parallel; Over voltage relay 5 is connected to resistance 4 two ends that suppress in parallel; Under-voltage replay 6 is connected to resistance 4 two ends that suppress in parallel.
The described Standard resistance range that suppresses resistance 4 in parallel is 35 ohm～250 ohm.
Principle of work of the present utility model is:
1, first by single-phase potential transformer 1, primary side fuse 2, secondary side fuse 3, in parallelly suppress resistance 4, over voltage relay 5, under-voltage replay 6 each several parts to press Fig. 3 connection good.
2, primary side one end of single-phase potential transformer 1 is connected to A, B, the arbitrary phase bus of C, other end ground connection through primary side fuse 2; Single-phase potential transformer 1 secondary side one end is connected to one end that suppresses resistance 4 in parallel by secondary side fuse 3, and the other end is connected to the other end ground connection of suppressing resistance 4 in parallel; Over voltage relay 5 and under-voltage replay 6 are connected in parallel in the two ends that suppress resistance 4 in parallel.
3, the voltage at the two ends that suppress resistance 4 in parallel is proportional to the primary side voltage of single-phase potential transformer 1, is proportional to system busbar B phase (primary side of supposing single-phase potential transformer 1 is connected to B phase bus) voltage (ratio value of direct ratio depends on single-phase potential transformer 1 no-load voltage ratio).
What 4, over voltage relay 5 and under-voltage replay 6 were experienced is the both end voltage that suppresses resistance 4 in parallel, and this is experienced voltage and is proportional to system busbar B phase (primary side of supposing single-phase potential transformer 1 is connected to B phase bus) voltage (ratio value of direct ratio depends on single-phase potential transformer 1 no-load voltage ratio).
5, set the setting valve of over voltage relay 5 and under-voltage replay 6.The setting valve of over voltage relay 1KV can be set to 1.5pu(perunit value); The setting valve of under-voltage replay 2KV can be set to 0.5pu(perunit value).
6, in the time that system is normal, the voltage that suppresses resistance R two ends in parallel is B phase (primary side of supposing single-phase potential transformer 1 is connected to B phase bus) secondary side ratings, V=1.0pu(perunit value), do not exceed the setting valve 1.5pu(perunit value of over voltage relay 1KV), therefore over voltage relay 1KV is failure to actuate; Not lower than under-voltage replay 2KV setting valve 0.5pu(perunit value), therefore under-voltage replay 2KV is failure to actuate.
7, over voltage relay 1KV and under-voltage replay 2KV are all failure to actuate, and illustrative system is normal, and device does not signal.
8, in the time of system B phase singlephase earth fault (primary side of supposing single-phase potential transformer 1 is connected to B phase bus), the voltage that suppresses resistance R two ends in parallel is 0, V=0, lower than under-voltage replay 2KV setting valve 0.5pu(perunit value), therefore under-voltage replay 2KV action; Do not exceed the setting valve 1.5pu(perunit value of over voltage relay 1KV), therefore over voltage relay 1KV is failure to actuate.
9, under-voltage replay 2KV action, its normally closed contact closure, as shown in Figure 4.Illustrating that single-phase potential transformer 1 connects there is singlephase earth fault mutually, and monitoring device just sends " system B phase single-phase earthing " failure alarm signal.
10, in the time of system A phase or C phase singlephase earth fault (primary side of supposing single-phase potential transformer 1 is connected to B phase bus), the voltage that suppresses resistance R two ends in parallel is 1.73 times of ratings, V=1.73pu(perunit value), exceed the setting valve 1.5pu(perunit value of over voltage relay 1KV), therefore over voltage relay 1KV action; Not lower than under-voltage replay 2KV setting valve 0.5pu(perunit value), therefore under-voltage replay 2KV is failure to actuate.
11, over voltage relay 1KV action, its normal opened contact closure, as shown in Figure 4.Illustrate in all the other two-phases and have one singlephase earth fault occurs mutually, monitoring device just sends " system A phase or C phase single-phase earthing " failure alarm signal.
The beneficial effects of the utility model are: simple in structure, cost is lower; By utilizing arbitrary phase-to-ground voltage to judge, be not subject to the impact of system capacitive current size, be not subject to the impact of zero-sequence current filtrator out-of-balance current.
Brief description of the drawings
Fig. 1 monitors isolated neutral system generation singlephase earth fault schematic diagram with residual voltage in prior art;
Fig. 2 monitors isolated neutral system generation singlephase earth fault schematic diagram with zero-sequence current in prior art;
Fig. 3 is circuit theory diagrams of the present utility model;
Fig. 4 is signal circuit figure of the present utility model;
Each label in figure: 1 is that single-phase potential transformer, 2 is that primary side fuse, 3 is that secondary side fuse, 4 is that over voltage relay, 6 is under-voltage replay for parallel connection suppresses resistance, 5.
Embodiment
Embodiment 1: as Figure 1-4, a kind of isolated neutral system singlephase earth fault monitoring device, comprises single-phase potential transformer 1, primary side fuse 2, secondary side fuse 3, resistance 4, over voltage relay 5, the under-voltage replay 6 of suppressing in parallel; Wherein single-phase potential transformer 1 primary side is connected to arbitrary phase in mutually of A phase, B phase, C and is only connect a phase, other end ground connection by primary side fuse 2; Single-phase potential transformer 1 secondary side one end is connected to one end that suppresses resistance 4 in parallel by secondary side fuse 3, and the other end is connected to the other end ground connection of suppressing resistance 4 in parallel; Over voltage relay 5 is connected to resistance 4 two ends that suppress in parallel; Under-voltage replay 6 is connected to resistance 4 two ends that suppress in parallel.
The described Standard resistance range that suppresses resistance 4 in parallel is 35 ohm～250 ohm.
By reference to the accompanying drawings embodiment of the present utility model is explained in detail above, but the utility model is not limited to above-mentioned embodiment, in the ken possessing those of ordinary skill in the art, can also under the prerequisite that does not depart from the utility model aim, make various variations.
Claims (2)
1. an isolated neutral system singlephase earth fault monitoring device, is characterized in that: comprise single-phase potential transformer (1), primary side fuse (2), secondary side fuse (3), resistance (4), over voltage relay (5), the under-voltage replay (6) of suppressing in parallel; Wherein single-phase potential transformer (1) primary side is connected to arbitrary phase in mutually of A phase, B phase, C and is only connect a phase, other end ground connection by primary side fuse (2); Single-phase potential transformer (1) secondary side one end is connected to one end that suppresses resistance (4) in parallel by secondary side fuse (3), and the other end is connected to the other end ground connection of suppressing resistance (4) in parallel; Over voltage relay (5) is connected to resistance (4) two ends that suppress in parallel; Under-voltage replay (6) is connected to resistance (4) two ends that suppress in parallel.
2. isolated neutral system singlephase earth fault monitoring device according to claim 1, is characterized in that: the described Standard resistance range that suppresses resistance (4) in parallel is 35 ohm～250 ohm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420159472.7U CN203811749U (en) | 2014-04-03 | 2014-04-03 | Single-phase ground fault monitoring device for non-grounded system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420159472.7U CN203811749U (en) | 2014-04-03 | 2014-04-03 | Single-phase ground fault monitoring device for non-grounded system |
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| CN203811749U true CN203811749U (en) | 2014-09-03 |
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| CN201420159472.7U Expired - Fee Related CN203811749U (en) | 2014-04-03 | 2014-04-03 | Single-phase ground fault monitoring device for non-grounded system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105186470A (en) * | 2015-09-10 | 2015-12-23 | 国网江西省电力科学研究院 | Single-phase ground fault processing method for 10kV ungrounded system |
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2014
- 2014-04-03 CN CN201420159472.7U patent/CN203811749U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105186470A (en) * | 2015-09-10 | 2015-12-23 | 国网江西省电力科学研究院 | Single-phase ground fault processing method for 10kV ungrounded system |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140903 Termination date: 20150403 |
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| EXPY | Termination of patent right or utility model |