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Specific classification of leakage relay

Classification of leakage relays


1. Ordinary current-operated leakage relay


The ordinary current-operated leakage relay is a numerical leakage relay, and its working principle is relatively simple. When the three-phase combined vector value of the electric current signal in the line exceeds the rated operating value of the leakage relay, the leakage relay sends a signal to cut off the power.


The shortcoming of this leakage relay is that it cannot distinguish between sudden and slow contact (leakage) electrical signals, and it detects that there is a large contact (leakage) protection dead zone (non-sensitive action phase) in the three-phase imbalanced line . This leakage relay has a simple structure, and is more suitable for circuits with low insulation level, low leakage current (generally below 30 mA) or three-phase leakage current values ​​that are more balanced, and combined with small total leakage current for contact (leakage) protection.


Classification of leakage relays


2.Pulse current action leakage relay


Pulse current operated leakage relays are differential leakage relays. This product judges the work according to the instantaneous change of ground current in the line. For non-abrupt current signals, such as the leakage current inherent in the line itself, as long as it does not exceed the upper limit set by the product, the leakage relay will Does not work.


This type of leakage current leakage relay has greater grid adaptability than ordinary leakage relays and has a larger protection range than ordinary types. It can be used for lines with low leakage current (the total leakage current of the protected line is less than 75 milliamps) as contact leakage. Total protection. Because it can not completely overcome the impact of electric shock, in the line with a large leakage current, there is a shortcoming of a large dead zone in the electric leakage protection zone.


3, phase detection, amplitude current action type leakage relay


This type of product uses the characteristic of 120 ° phase difference of three-phase currents to sample and track a fixed phase angle of the electric (leakage) electrical signal, and compares and judges the method of phase detection and amplitude detection circuit to detect any phase in the three-phase line. The current signal can make a correct response, and its action has nothing to do with the phase of the leakage current in the line. For the total leakage current of the line, the leakage relay has also set an upper limit value. If it exceeds the upper limit value, it will also trip.


This type of leakage relay eliminates the shortcomings of the insensitive phase of ordinary current and pulse current leakage relays, and has ideal operating characteristics. It is especially suitable for circuits with poor insulation levels, large leakage currents, and complex electrical load conditions in rural China. , Can be used as the overall protection of electric shock and leakage of lines and equipment.