Intelligent air switch capable of detecting direct current grounding

Abstract

The invention discloses an intelligent air switch capable of detecting direct current grounding. The intelligent air switch comprises a first Hall sensor for collecting the positive pole current I1x of the air switch, a second Hall sensor for collecting the negative pole current I2x of the air switch, a calculation element for calculating the difference value of the positive pole current I1x and the negative pole current I2x, a logic judgment element which logically compares the difference value calculated by the calculation element with a set value Ix, a control element, and a signal lamp L connected with the control element. With the intelligent air switch of the invention adopted, the detection precision of direct current grounding can be so high that the direct current grounding of each branch circuit can be detected, a circuit switching-off method for further search is not needed, and therefore, convenience can be brought out, and the detection efficiency of the direct current grounding can be improved; when the traditional circuit switching-off method is adopted to deal with a direct current grounding problem, uncertainties will be increased, and the traditional circuit switching-off method is time-consuming and effort-consuming, and the power outage of the primary equipment of a substation can be brought about. The intelligent air switch can perform intelligent detection, so that hidden troubles can be eliminated. The intelligent air switch is provided with a time-delay action element, so that the reliability of detection can be ensured, the condition of a branch circuit can be accurately detected; and the detection of the intelligent air switch of the present invention is fast and efficient and can save time and labor.

Description

technical field [0001] The invention relates to an intelligent air switch capable of detecting DC grounding. Background technique [0002] The DC system provides power for substation communication devices, protection devices, and monitoring systems, and is the power guarantee for the normal operation of substation secondary equipment and automatic devices. However, during long-term operation, due to environmental changes, climate changes, aging of cables and connectors, equipment problems, etc., the insulation of some components with weak insulation will be reduced or even damaged, resulting in DC grounding. In DC grounding, the most harmful thing is two-point grounding. If two-point grounding occurs in the DC system, it may constitute a grounding short circuit, causing relay protection, signals, and automatic devices to malfunction or refuse to operate, or cause power fuses to blow. Automatics lose power. [0003] by figure 1 Take an example to illustrate the hazards of ...

AI Technical Summary

Problems solved by technology

However, during long-term operation, due to changes in the environment, climate changes, aging of cables and connectors, problems with the equipment itself, etc., the insulation of some components with weak insulation will be reduced or even damaged, resulting in DC grounding

In DC grounding, the most harmful thing is two-point grounding. If two-point grounding occurs in the DC system, it may constitute a grounding short circuit, causing relay protection, signals, and automatic devices to malfunction or refuse to operate, or cause power fuses to blow. Automatic device loses power

[0003] by figure 1 Take an example to explain in detail the hazards of DC two-point grounding: (1) cause malfunction of protection and automatic devices

like figure 1 As shown, when the DC grounding occurs at two points A and B, the contacts of the current relay KA1 and KA2 are short-circuited to start KM, and the KM contact is closed to trip; when the two points A and C are grounded, the KM contact is short-circuited and the Tripping; A, D two points, D, F two points, etc. grounding will also cause device malfunction

[0004] (2) Cause relay protection and automatic device to refuse action

like figure 1 If the grounding occurs at two points B and E, two points D and E or two points C and E, the tripping closing coil and the protection relay coil are shorted by the grounding point and cannot act, causing the switch to refuse to move

[0005] (3) Cause a short circuit to blow the power fuse, and cause the protection, automatic device and control circuit to lose power

The disadvantage is that the device can only monitor the specific grounding circuit or branch of the DC circuit grounding. When there are several sub-branches under the branch, it needs to be further judged by the method of pulling

Technically it is limited by the number of monitoring points installed, it is difficult to reduce the ground fault to a small range

Moreover, the device must be constructed and installed, which is very inconvenient for the transformation of the old system

Such devices generally have the problems of low detection accuracy, poor resistance to distributed capacitance interference, and many false alarms.

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