CN205562783U - Open circuit current load case is prevented to serial -type - Google Patents

Abstract

The utility model discloses a series anti-open-circuit current load box, which comprises a first output terminal, a second output terminal and several groups of loads sequentially connected in series between the two; each group of loads is connected in parallel with a switch; each of the The group load includes series resistance and inductance. Through the opening and closing of the switch, the load box can be controlled to achieve a variety of different load values. When any switch is opened or closed, the load box will not appear in an open circuit state and will not be in operation. During the process, there is a state of disconnecting the secondary load of the current transformer, and the secondary load can be switched under the test state of the current transformer, which saves the test time, reduces the test workload, and reduces the working time of the current transformer due to the test. The test time is reduced, and at the same time, the load superposition method is adopted to improve the efficiency of a single load, greatly reduce the number of components, and save material costs.

Description

Series anti-open circuit current load box

technical field

The utility model relates to a current load box, in particular to a series anti-open circuit current load box, which belongs to the technical field of current transformer testing.

Background technique

The error data of the current transformer is different under different load conditions, and basically changes linearly. In order to ensure that the error data of the current transformer belt under different load conditions are all within the error limit, when performing error calibration on the current transformer It needs to be carried out under the rated load and lower limit conditions of the current transformer. JJG1021-2007 "Power Transformer" Verification Regulations, JJG313-2010 "Measurement Current Transformer" verification regulations both stipulate that when measuring the current transformer error, it is necessary to connect the load to the secondary winding of the current transformer under test, usually Realize with the current load box, the current load box needs to use the lower limit load gear and the rated load gear when in use.

As shown in Figure 1, a traditional current load box is composed of 14 sets of inductors, resistors and switches, forming a load value of 0VA, 2.5VA, 5VA, 6.25VA, 7.5VA, 10VA, 12.5VA with a power factor of 0.8 , 14 different loads of 15VA, 20VA, 25VA, 30VA, 40VA, 50VA, 60VA. When the switch contact S is connected to the K1 contact, the load value of the current load box is 2.5VA; when the switch contact S is connected to the K2 contact, the load value of the current load box is 3.75VA...Dial switch When the contact S is connected to the K14 contact, the load value of the current load box is 60VA. When the current load box is switched from one load to another load, the switch contact S needs to move from one contact point to another. During the movement, the current load box is in an open circuit state.

The above-mentioned traditional current load box, due to the internal structure, will cause the secondary circuit of the current transformer to open when switching the load gear, so the load value of the load box cannot be directly switched under the test state of the current transformer, and the primary current needs to be returned to zero. Otherwise, the primary circuit of the current transformer will be open and the secondary circuit will be open during the test, which may cause high voltage to damage the current transformer or test equipment, and even threaten personal safety.

Utility model content

The main purpose of this utility model is to overcome the defects of the prior art and provide a series type anti-open circuit current load box, which will not cause the state of disconnecting the secondary load of the current transformer during operation, and prevents the current from being caused by improper operation. Equipment damage and personal injury caused by the secondary open circuit of the transformer, and the secondary load can be switched under the test state of the current transformer, which saves the test time, reduces the test workload, and shortens the working time of the current transformer due to the test. time, reducing the risk of experimentation.

In order to achieve the above object, the technical solution adopted in the utility model is:

The series anti-open-circuit current load box is characterized in that it includes a first output terminal, a second output terminal and several groups of loads connected in series between the two in sequence; each group of loads is connected in parallel with a switch; each group of loads is Including resistors and inductors in series.

The aforementioned series-type anti-open-circuit current load box is characterized in that there are six groups of loads connected in series between the first output end and the second output end, sequentially the first group of loads, the second group of loads, the third group of loads, and the third group of loads. The four loads, the fifth load and the sixth load, the load values are 1.25VA, 2.5VA, 5VA, 10VA, 20VA, 40VA respectively, and the power factor is 0.8.

The utility model has the following beneficial effects:

(1) The traditional current load box needs 14 sets of inductors, resistors and switches to realize 14 different loads. The utility model series anti-open circuit current load box only uses 6 sets of inductors, resistors and switches to realize 64 kinds of loads. Less, more load value, using the load superposition method, which improves the efficiency of a single load, greatly reduces the number of components and saves material costs.

(2) When the traditional current load box is switched from one load gear to another load gear, the current load box is in an open circuit state, which makes the secondary circuit of the current transformer open. The voltage damages the current transformer or other test equipment, and even threatens personal safety; the series type anti-open circuit current load box of the utility model, when any switch is opened and closed, the load box will not appear in an open circuit state, and will not be in the process of operation. There is a state of disconnecting the secondary load of the current transformer, and the secondary load can be switched under the test state of the current transformer, which saves the test time, reduces the test workload, and shortens the working time of the current transformer due to the test. Reduced trial risk.

Description of drawings

Figure 1 is a schematic diagram of a traditional current load box circuit.

Fig. 2 is a schematic circuit diagram of the series anti-open-circuit current load box of the present invention.

detailed description

Below in conjunction with accompanying drawing, the utility model is further described. The following examples are only used to illustrate the technical solution of the utility model more clearly, but not to limit the protection scope of the utility model.

A series anti-open-circuit current load box, the circuit principle is shown in Figure 2, including a first output terminal A, a second output terminal B and a resistance R1, an inductance L1, a resistance R2, an inductance L2, Resistor R3, inductor L3, resistor R4, inductor L4, resistor R5, inductor L5, resistor R6, inductor L6. Resistor R1 and inductor L1, resistor R2 and inductor L2, resistor R3 and inductor L3, resistor R4 and inductor L4, resistor R5 and inductor L5, resistor R6 and inductor L6 constitute six groups of loads with a power factor of 0.8, and the load values are 1.25 in turn VA, 2.5VA, 5VA, 10VA, 20VA, 40VA, each group of loads is connected in parallel with a switch, followed by K1, K2, K3, K4, K5, K6. By controlling the opening and closing of the switch, 64 different loads with a load range of 0~78.75VA and a minimum step value of 1.25VA can be formed, which fully meets the error calibration requirements of current transformers.

The following examples illustrate the realization of several load values:

When the switches are all closed, the 6 groups of resistors and inductors are all short-circuited, and the load value is 0VA;

When K1 is open and other switches are closed, the load value is 1.25VA;

When K2 is open and other switches are closed, the load value is 2.5VA;

When K1 and K2 are open, and the rest of the switches are closed, the load value is 3.75VA;

When K3 is open and other switches are closed, the load value is 5VA;

When K1 and K3 are turned on and the rest of the switches are turned on, the load value is 6.25VA;

When K2 and K3 are open, and the rest of the switches are closed, the load value is 7.5VA;

When K1, K2, and K3 are open, and the rest of the switches are all closed, it is 8.75VA;

When K4 is open and other switches are closed, 10VA;

...

K2K3K4K5K6 are all open, when K1 is closed, the load value is 77.5VA;

With all switches open, the load value is 78.5VA.

When using the utility model series anti-open circuit current load box to carry out the current transformer error verification test, the current transformer can switch the gear position of the load box under the test state, and there will be no open circuit, which can prevent the current transformer from being disconnected under the test state. Equipment damage and personal injury caused by the secondary circuit being in an open state; the full load test can be done by using the current rise, and the light load test can be done by using the current drop, which reduces the test time and improves work efficiency; reduces the working time of the current transformer during the test, Therefore, the damage to the equipment in the error calibration system of the current transformer is reduced, and the risk of the test is reduced.

The series anti-open circuit current load box of the utility model only needs 6 groups of resistors, inductors and 6 switches to realize 64 different load values from 0VA to 78.75VA, which can be reduced when the load capacity range and the number of gears are increased. It reduces the number of components and saves material costs. At the same time, only 6 sets of switches are needed to realize switching of 64 gears, which reduces the number of switches and reduces the equipment failure rate caused by switch failure.

In summary, the utility model is simple in structure, easy to implement, low in cost and has good application prospects.

The above is only the preferred embodiment of the utility model, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the utility model, some improvements and deformations can also be made. And deformation should also be regarded as the protection scope of the present utility model.

Claims (2)

1. The series anti-open-circuit current load box is characterized in that it includes a first output terminal, a second output terminal and several groups of loads connected in series between the two in sequence; each group of loads is connected in parallel with a switch; each group of Both loads consist of series resistance and inductance. 2. The series anti-open-circuit current load box according to claim 1, wherein the loads connected in series between the first output end and the second output end are six groups, followed by the first group of loads and the second group of loads , The third group of loads, the fourth group of loads, the fifth group of loads and the sixth group of loads, the load values are 1.25VA, 2.5VA, 5VA, 10VA, 20VA, 40VA, and the power factor is 0.8.