CN215005577U

CN215005577U - Distribution network alternating current sensor circuit and current sensor

Info

Publication number: CN215005577U
Application number: CN202120092124.2U
Authority: CN
Inventors: 顾红波; 姚志超; 徐新生
Original assignee: Nanjing Dandick Electric Instrument Co ltd
Current assignee: NANJING DANDICK ELECTRIC INSTRUMENT Co.,Ltd.; Nanjing Ronghe Electric Co., Ltd
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2021-12-03
Anticipated expiration: 2031-01-14

Abstract

The utility model discloses a join in marriage net alternating current sensor circuit and have its net alternating current sensor of joining in marriage, wherein join in marriage net alternating current sensor circuit and include a plurality of phase current transformers and a zero sequence current transformer that has a plurality of primary windings, a plurality of primary windings of zero sequence current transformer respectively with every phase current transformer's secondary winding electric connection, zero sequence current transformer's secondary winding parallel connection has sampling resistor. According to the distribution network alternating current sensor circuit of the technical scheme, only one zero sequence current transformer is needed, the measuring range of the zero sequence current transformer does not need to be the same as that of a phase current transformer, the size of a magnetic core of the zero sequence current transformer is reduced, the production cost of the distribution network alternating current sensor with the distribution network alternating current sensor circuit is reduced, and the sampling resistor of the zero sequence current sensor can be prevented from being burnt when the phase current is over-current.

Description

Distribution network alternating current sensor circuit and current sensor

Technical Field

The utility model relates to a distribution equipment field, in particular to join in marriage net alternating current sensor electric current and current sensor.

Background

The current sensor is a common device used for monitoring the line current condition in a power grid, and the existing zero-sequence current sensor mainly adopts two methods, namely a three-phase magnetic potential synthesis method or a three-phase current synthesis method. The three-phase magnetic potential synthesis method needs three-phase lines to penetrate through the through hole of the zero sequence current transformer, so that the magnetic path of the magnetic core of the zero sequence current transformer is too long, and large errors can be generated due to uneven winding of the winding. The three-phase current synthesis method needs three zero-sequence current transformers, the measuring range of each zero-sequence current transformer needs to be consistent with that of the phase current transformer, the cost is high, and the sampling resistor of the zero-sequence current transformer can be burnt when a certain phase is in short circuit

SUMMERY OF THE UTILITY MODEL

Utility model purpose: the utility model aims at providing a join in marriage net alternating current sensor circuit can reduce zero sequence current sensor's cost, avoids zero sequence current sensor's sampling resistor to burn out.

Another object of the utility model is to provide a join in marriage net current sensor with above-mentioned net current sensor circuit, low in manufacturing cost, the size is little and the reliability is high.

The technical scheme is as follows: join in marriage net alternating current sensor circuit, including phase current transformer and a zero sequence current transformer, zero sequence current transformer has a plurality of primary windings, a plurality of primary windings of zero sequence current transformer respectively with every phase current transformer's vice limit winding electric connection, zero sequence current transformer's vice limit winding parallel connection has sampling resistor.

Furthermore, the primary winding of the zero-sequence current transformer is electrically connected with the secondary winding of the corresponding phase current transformer through a sampling resistor.

According to join in marriage net alternating current sensor, include: the magnetic cores of the phase current transformers are annular; the zero-sequence current transformer is provided with a plurality of primary windings, the primary windings of the zero-sequence current transformer are respectively and electrically connected with the corresponding secondary windings of the phase current transformer, and the secondary windings of the zero-sequence current transformer are connected with a sampling resistor in parallel; the shell is used for connecting the phase current transformers and the zero sequence current transformer into a whole; and the terminals are respectively and electrically connected with the corresponding secondary windings of the phase current transformer and the zero sequence current transformer.

Furthermore, the shell is an injection molding shell poured and encapsulated by epoxy resin.

Further, the magnetic core of the phase current transformer is an amorphous magnetic core, and the magnetic core of the zero sequence current transformer is a nanocrystalline magnetic core.

Has the advantages that: compared with the prior art, the utility model has the advantages of as follows:

1. only three large-range phase current transformers and one small-range zero sequence current transformer are needed to realize the method, and the manufacturing cost and the size are reduced.

2. And the sampling resistor of the zero sequence current transformer cannot be burnt when the phase current is in a short circuit or overcurrent condition.

Drawings

Fig. 1 is a schematic diagram of the ac current sensor circuit for distribution network of the present invention.

Detailed Description

The technical solution of the present invention will be further explained with reference to the accompanying drawings.

Referring to fig. 1, according to the utility model discloses distribution network alternating current sensor circuit, including phase current transformer and zero sequence current transformer. The zero-sequence current transformer is provided with a plurality of primary windings, and each primary winding is correspondingly and electrically connected with the secondary winding of one phase current transformer. It can be understood that the secondary winding of each phase current transformer and the secondary winding of the zero sequence current transformer output the measured current value through the sampling resistor.

According to the distribution network alternating current sensor circuit in the technical scheme, the three primary windings of the zero sequence current transformer are directly and electrically connected with the secondary windings of the three phase current transformers, the measured values of the three phase currents are directly obtained, and the zero sequence current is synthesized at the secondary windings of the zero sequence current transformer through the electromagnetic induction principle. Because the zero sequence current transformer does not directly sample the three phase currents, the measuring range of the zero sequence current transformer can be smaller than that of the phase current transformer. Generally, the size of the magnetic core of the phase current transformer is 110mm in outer diameter, 90mm in inner diameter and 30mm in height, the outer diameter of the zero sequence current transformer only needs 40mm, 30mm in inner diameter and 10mm in height, the cost of the saved magnetic core can reach 40%, the winding cost of the corresponding transformer is reduced by 50%, meanwhile, the thickness of the injection molding shell with the circuit structure can be reduced by about 40%, and the whole weight is reduced by about 30%.

Meanwhile, because the output of the phase current transformer is milliampere current, the output is only 1 to 2A even if the output is amplified by 10 times under the overcurrent condition, and even if the magnetic core of the small-sized zero-sequence current transformer is far from a saturation state, the zero-sequence current condition can be accurately reflected. And the output of the secondary winding of the zero sequence current transformer is milliampere level, the sampling resistor can be kilo-ohm level, the power consumption of the sampling resistor R4 of the zero sequence current transformer is only watt level under the condition of overcurrent, and the sampling resistor R4 of the zero sequence current transformer cannot be burnt.

Referring to fig. 1, in the present embodiment, the secondary windings of three phase current transformers TA1, TA2, and TA3 are electrically connected to three primary windings AL1, BL1, and CL1 of a zero sequence current transformer TA4 through sampling resistors R1, R2, and R3, respectively, and the three primary windings of the zero sequence current transformer are insulated and independent from each other, which meets the voltage withstand insulation requirement between the windings of the group standard T/ZDG018-2018 published by the institute of electrical and technology in china.

According to the utility model discloses join in marriage net alternating current sensor has above-mentioned net alternating current sensor circuit structure of joining in marriage. The phase current transformer and the zero sequence current transformer are connected into a whole through the shell. In this embodiment, the distribution network ac current sensor adopts a through-type current sensor structure, the magnetic cores of the three phase current sensors adopt an annular structure, the secondary windings of the three phase current sensors are wound on the annular magnetic cores, and the primary circuits of the three-phase circuit respectively pass through the magnetic cores of the corresponding phase current sensors to serve as the primary windings of the phase current sensors. The primary winding of the zero-sequence current sensor is directly connected with the secondary winding of the phase current sensor to obtain phase current, so that a primary circuit does not need to penetrate through the magnetic core of the zero-sequence current transformer, the magnetic core of the zero-sequence current transformer does not need to be arranged side by side with the magnetic core of the phase current transformer, the thickness of a shell of the current sensor is reduced, and the installation size and the injection molding cost of the current sensor are reduced. The shell is provided with a plurality of terminals, each terminal is electrically connected with the corresponding secondary side winding of the phase current transformer and the zero sequence current transformer, and external equipment is electrically connected with the current transformers through the terminals to obtain measured phase current and zero sequence current values. It is understood that, in some embodiments, the housing is an injection molded housing encapsulated by epoxy resin, the magnetic core of the phase current transformer is an amorphous magnetic core, and the magnetic core of the zero sequence current transformer is a nanocrystalline magnetic core.

Claims

1. A distribution network alternating current sensor circuit is characterized by comprising a phase current transformer and a zero sequence current transformer, wherein the zero sequence current transformer is provided with a plurality of primary windings, the plurality of primary windings of the zero sequence current transformer are electrically connected with a secondary winding of each phase current transformer respectively, and the secondary winding of the zero sequence current transformer is connected with a sampling resistor in parallel.

2. The distribution network alternating current sensor circuit according to claim 1, wherein the primary windings of the zero sequence current transformers are electrically connected to the secondary windings of the corresponding phase current transformers through a sampling resistor respectively.

3. A distribution network ac current sensor, comprising:

the magnetic cores of the phase current transformers are annular;

the zero-sequence current transformer is provided with a plurality of primary windings, the primary windings of the zero-sequence current transformer are respectively and electrically connected with the corresponding secondary windings of the phase current transformer, and the secondary windings of the zero-sequence current transformer are connected with a sampling resistor in parallel;

the shell is used for connecting the phase current transformers and the zero sequence current transformer into a whole;

and the terminals are respectively and electrically connected with the corresponding secondary windings of the phase current transformer and the zero sequence current transformer.

4. The AC sensor for distribution network according to claim 3, wherein the primary winding of the zero sequence current transformer is electrically connected to the secondary winding of the corresponding phase current transformer through a sampling resistor.

5. The distribution network ac current sensor of claim 3, wherein the housing is an injection molded housing potted in epoxy.

6. The distribution network ac current sensor according to claim 3, wherein the magnetic core of the phase current transformer is an amorphous magnetic core, and the magnetic core of the zero sequence current transformer is a nanocrystalline magnetic core.