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3 gorge power station allows ground potential to lift the experiment studies
From;    Author:Stand originally

Be worth to raise earth mat to allow potential to lift certainly feasible, the influence that the character of labour frequency compression that protection equipment studied again in the article after the author was studying the labour frequency compression that controls cable is characteristic is worth to this, had a test. The result makes clear, the character of labour frequency compression that relay is isolated from is the crucial factor that affects this one value.

Keyword: Potential of ground of; of 3 gorge power station is elevatory; relay compression of; labour frequency is characteristic

1, foreword

Relay malfunctions in the system when should movement of ground of on the safe side, this is having all in all sense to systematic safety and stability. Because relay has ground connection to nod, the ground potential that the fault current place that earth mat has shed when breakdown so causes is elevatory on the insulation that also will be added in relay, whether can the insulation of relay bear this kind abrupt short when labour frequency high pressure is a notable problem. To 3 gorge power station, the biggest short-circuit current that has shed earth mat designs a value to be 34kA, the earth mat resistor of the 3 gorge power station that is located in granite region impossible under 0.06W [1] , this makes the ground potential of 3 gorge power station elevatory will be more than 2kV, need to rise namely allow ground potential elevatory value. In standard of domestic and international ground connection [2, 3] , what consider mainly is ground potential elevatory safe to person influence, did a large number of works [4 ~ 7] , but safe to low pressure and electronic equipment influence considers very few. Document [the co-ordination of insulation that the facility inside low-pressure system discussed in 8][9] , reference can be offerred on certain level. Civil [the 10] labour to controlling cable frequency compression character undertook study, reached a few very valuable conclusion.

The article labour to 2 equipment character of second of frequency bend over undertook experimenting study, allow a value to provide a basis to decide what earth mat potential lifts is optimal. Test result makes clear, the character of labour frequency compression that relay is isolated from is limitation rise the biggest the most crucial factor that allows ground potential to lift.

2, experiment preparation

2.1 test facilities and method experiment should the actual operating conditions of imitate relay, ground potential bears to lift suddenly when breakdown namely. This experiment method is the labour frequency high pressure with certain amplitude to add up to brake suddenly to be added in try article on, choose try article for groovy relay and solid state relay. Because relay tries,taste finite, every relay for many times pressurization, till insulation puncture till. Experiment in groovy relay in, the relay with bigger over all dimension (it is a few special relay normally) have ground contact of bolt of crust fixed position commonly, reason experiment voltage brings to bear on to do not have fixed position bolt normally in the; appearance is lesser general relay between the wiring column of fixed position bolt and coil, action voltage brings to bear on online circle and often shut relay of; solid state has 4 contact between contact, namely two communication are outputted (switch) contact, two dc are inputted (control) contact, the dc when relay works controls the positive electrode ground connection of contact, the anode that lets experiment voltage action control contact at dc so and communication are outputted (switch) between contact, dc controls the positive electrode contact of contact to be carried for high pressure, communication is outputted (switch) contact ground connection.
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