CN204882789U - CT polarity test device - Google Patents

Abstract

The utility model provides a CT polarity test device which includes: resistance (R1), resistance (R2), resistance (RS), diode (D), relay (CJ), switch (AN1), switch (AN2), switch (AN3), single -pole double -throw (K2), switch (K1), DC power supply (EC1), DC power supply (EC2), emitting diode (LED1), emitting diode (LED2). The utility model discloses satisfying relay protection job site's actual need completely, having characteristics such as test sensitivity, convenient operation, portable, reliable practicality, can improve site work efficiency greatly, and it is directly perceived, concrete to test light indication, electronic components power consumption is few, and is with low costs, and the power consumption is low, can be used to long -time test.

Description

CT polarity test device

technical field

The utility model relates to the technical field of power equipment maintenance and power meter testing, in particular to a CT polarity testing device.

Background technique

Based on the principle of electromagnetic induction, a current transformer (CT) converts a large current on the primary side into a small current on the secondary side for use. It is usually composed of a closed iron core and a winding. Its primary side winding is connected in series in the circuit of the current to be measured, and the secondary side winding is connected in series in the measuring instrument and the protection circuit. When the current transformer is working, the secondary side circuit is always closed, the working state of the current transformer is close to short circuit, and the secondary side cannot be opened.

In the secondary production work of the power system, the current transformer replacement and overhaul projects are often involved, and the polarity of the current transformer needs to be tested. The wrong polarity of the current transformer may lead to consequences such as malfunction and refusal of the relay protection device, which will have a huge impact on the reliable operation of the power grid.

Currently, current transformer polarity testing is divided into two methods:

One is to use a current transformer tester to test the polarity of the current transformer. This test method takes a long time and requires more test personnel, especially in some old substations where the test power supply is less and it is difficult to connect the power supply. Invisibly increased the time in the whole test.

The other is the method of testing the polarity of ordinary dry batteries. Specifically, ordinary dry batteries and ammeters are connected in series. This test method flows a current through the primary side of the transformer, and induces a small current on the secondary side, and judges the polarity of the current transformer by judging the direction of the current. . If the current transformer is relatively large, the secondary induced current will be very small, which requires high accuracy of the ammeter on the secondary side, and the cost will be high, and this method cannot be used for currents with relatively large transformation ratios. The transformer responds very well.

Utility model content

The purpose of the utility model is to provide a CT polarity testing device to realize the polarity testing of current transformers with sensitive testing, large dynamic range, portability and simple operation.

In order to achieve the above object, the technical scheme of the utility model is as follows:

A CT polarity testing device, which includes: a resistor (R1), the first end of the resistor (R1) is connected to the first end of a switch (AN2), and the second end of the resistor (R1) is connected to a diode (D ), the second end of the switch (AN2) is simultaneously connected to the first fixed end of a SPDT switch (K2), the first end of a switch (K1), and the first end of a resistor (R2); The cathode of the diode (D) is connected to the first input end of a relay (CJ) and the first end of a resistor (RS), and the second input end of the relay (CJ) is connected to the moving end of the SPDT switch (K2) , the second end of the resistor (RS) is connected to the first end of the switch (AN3); wherein, the relay (CJ) has at least two sets of output nodes (CJ-1, CJ-2), and two sets of output nodes (CJ- 1. In CJ-2), one is a normally open node and the other is a normally closed node; the negative pole of a DC power supply (EC2) is connected to the second terminal of the switch (AN3) and the second terminal of the SPDT switch (K2). The non-moving end, the cathode of a light-emitting diode (LED1), the cathode of a light-emitting diode (LED2), and the positive pole of the DC power supply (EC2) are connected to the second end of the switch (K1); the output node (CJ- 1) Connect between the second end of the resistor (R2) and the anode of the light emitting diode (LED1), the output node (CJ-2) of the relay (CJ) is connected between the second end of the resistor (R2), the anode of the light emitting diode (LED2) ) between the anodes.

Preferably, the above-mentioned CT polarity testing device further includes: a DC power supply (EC1), and a switch (AN1) connected to the DC power supply (EC1).

Preferably, in the above CT polarity testing device, the switch (AN1), the switch (AN2), and the switch (AN3) are push button switches.

It can be seen from the analysis that the utility model fully meets the actual needs of the relay protection work site, has the characteristics of sensitive testing, convenient operation, portability, reliability and practicality, etc., can greatly improve the work efficiency on site, and the test light indication is intuitive and specific, and electronic components Low power consumption, low cost, low energy consumption, can be used for long-term testing.

Description of drawings

Fig. 1 is the principle circuit diagram of the utility model embodiment;

Fig. 2 is a schematic diagram of the wiring of the relay CJ of the embodiment of the present invention.

Detailed ways

The utility model will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 shows the circuit structure of the embodiment of the present invention, and the circuit connection structure between it and the current transformer CT.

As shown in Figure 1, the utility model embodiment includes resistor R1, resistor R2, resistor RS, diode D, relay CJ, switch AN1, switch AN2, switch AN3, SPDT switch K2, switch K1, DC power supply EC1, DC Power supply EC2, light emitting diode LED1, light emitting diode LED2.

Specifically, the first end of the resistor R1 is connected to the first end of the switch AN2, the second end of the resistor R1 is connected to the anode of the diode D, and the second end of the switch AN2 is simultaneously connected to the first end of the SPDT switch K2. The moving terminal K21, the first terminal of the switch K1, and the first terminal of the resistor R2.

The cathode of the diode D is connected to the first input end of the relay CJ and the first end of the resistor RS, the second input end of the relay CJ is connected to the moving end of the SPDT switch K2, and the second end of the resistor RS is connected to the switch AN3 first end. As shown in Figure 2, the relay CJ has at least two groups of output nodes CJ-1, CJ-2, and among the two groups of output nodes CJ-1, CJ-2, one is a normally open node (node CJ-2), and the other It is a normally closed node (node CJ-1). The positive pole of the relay CJ input terminal is connected between the diode D and the resistor RS, and the negative pole of the relay CJ input terminal is connected with the moving terminal of the switch K2. When the relay CJ current flows in from the positive pole, the node CJ-2 is closed and the node CJ-1 is opened. When the relay CJ current flows in from the negative pole, the node CJ-1 is closed and the node CJ-2 is opened. The output node CJ-1 of the relay CJ is connected between the second end of the resistor R2 and the anode of the light-emitting diode LED1, and the output node CJ-2 of the relay CJ is connected between the second end of the resistor R2 and the anode of the light-emitting diode LED2.

The negative pole of the DC power supply EC2 is connected to the second terminal of the switch AN3, the second fixed terminal K22 of the SPDT switch K2, the cathode of the light-emitting diode LED1, and the cathode of the light-emitting diode LED2, and the positive pole of the DC power supply EC2 is connected to the first terminal of the switch K1. Two ends.

The DC power supply EC1 and a switch AN1 connected to the DC power supply EC1 are of an external structure and may not be integrated in the above circuit structure.

Preferably, the switch AN1, the switch AN2, and the switch AN3 are push button switches.

During the specific application of the embodiment of the present invention, it is basically divided into three processes, which are respectively:

1. Working process

Before working, the switch K1 is closed, and the light-emitting diode LED1 used for power supply indication lights up, which means that this embodiment can be used. Switch the switch K2 to the "working" position, that is, the first fixed end K21, and the test can be performed at this time.

The DC power supply EC1 is an external power supply, its positive pole is connected to the primary side terminal P1 of the current transformer CT, and its negative pole is connected to the primary side terminal P2 side of the current transformer CT. Press the test button of switch AN1, at this time, current flows through the primary side of the current transformer CT, and the current induced by the secondary side flows out from terminal S1, and flows through diode D, relay CJ, SPDT switch K2 in turn, and then flows Back to the secondary side terminal S2 of the current transformer CT. At this time, the relay CJ operates with forward current flow, the node CJ-2 is closed, and the node CJ-1 is opened. At this time, the current of the DC power supply EC2 flows through the switch K1, the resistor R2, the node CJ-2, and the light-emitting diode LED2 used to represent the same polarity to form a loop. At this time, the light-emitting diode LED2 lights up, representing the CT test of the current transformer for the same polarity.

2. The recovery process

Since the relay CJ used in this embodiment is a magnetic latching relay, when the relay CJ is activated, the node CJ-2 will remain closed, so a return circuit is provided.

The external circuit is disconnected, the switch K1 is closed, and the switch K2 is switched to the first fixed end K21. Now press the reset button of switch AN3, the current flows from the positive pole of DC power supply EC2 through switch K1, switch K2, relay CJ, resistor RS, switch AN3, and then flows back to the negative pole of DC power supply EC2. At this time, the relay CJ flows reverse current, the node CJ-1 is closed, and the node CJ-2 is disconnected. At this time, the light-emitting diode LED1 emits light and returns to the state before the test.

3. Device self-inspection process

Considering that the relay CJ has a corresponding service life, this embodiment designs a self-inspection circuit to detect the condition of the relay CJ.

Before the self-test, the switch K1 is closed, and the switch K2 is switched to the test position, that is, the second fixed end K22. At this time, press the debugging button of switch AN2 to form a loop. The current flows out from the positive pole of DC power supply EC2, flows through switch K1, switch AN2, resistor R1, diode D, relay CJ, switch K2 in turn, and then flows back to the negative pole of DC power supply EC2. At this time, the input terminal of the relay CJ flows current in the forward direction, the relay CJ acts, the node CJ-2 is closed, the node CJ-1 is disconnected, and the current of the DC power supply EC2 flows through the switch K1, the resistor R2, the node CJ-2, and the light The diode LED2 constitutes a loop, and if the light-emitting diode LED2 emits light, it proves that the relay CJ can continue to be used normally.

To sum up, the utility model can achieve the effects of small size, portability, and ease of use, which changes the traditional test method and greatly improves the on-site work efficiency, and the test light indication is intuitive and specific, and the power consumption of electronic components is low. for long-term testing.

It can be known from technical knowledge that the utility model can be realized through other implementations without departing from its spirit or essential features. Accordingly, the above-disclosed embodiments are, in all respects, illustrative and not exclusive. All changes within the scope of the utility model or within the range equivalent to the utility model are included in the utility model.

Claims (3)

1. A CT polarity testing device, characterized in that, comprising: Resistor (R1), the first end of the resistor (R1) is connected to the first end of a switch (AN2), the second end of the resistor (R1) is connected to the anode of a diode (D), the second end of the switch (AN2) terminal is simultaneously connected to the first fixed terminal of a single pole double throw switch (K2), the first terminal of a switch (K1), and the first terminal of a resistor (R2); The cathode of the diode (D) is connected to the first input end of a relay (CJ) and the first end of a resistor (RS), and the second input end of the relay (CJ) is connected to the moving end of the SPDT switch (K2) , the second end of the resistor (RS) is connected to the first end of the switch (AN3); wherein, the relay (CJ) has at least two sets of output nodes (CJ-1, CJ-2), and two sets of output nodes (CJ- 1. In CJ-2), one is a normally open node and the other is a normally closed node; The negative pole of a DC power supply (EC2) is connected to the second end of the switch (AN3), the second fixed end of the SPDT switch (K2), the cathode of a light emitting diode (LED1), and the cathode of a light emitting diode (LED2) , the positive pole of the DC power supply (EC2) is connected to the second end of the switch (K1); The output node (CJ-1) of the relay (CJ) is connected between the second end of the resistor (R2) and the anode of the light-emitting diode (LED1), and the output node (CJ-2) of the relay (CJ) is connected to the resistor (R2 ) between the second terminal and the anode of the light emitting diode (LED2). 2. CT polarity testing device according to claim 1, is characterized in that, also comprises: A DC power source (EC1), and a switch (AN1) connected to the DC power source (EC1). 3. The CT polarity testing device according to claim 2, characterized in that the switch (AN1), the switch (AN2), and the switch (AN3) are push button switches.