Loop resistance
The loop resistance value is a parameter to characterize whether the conductive loop connection is good or not, and various types of products have specified a certain range of values. If the loop resistance exceeds the specified value, it may be that the connection contact of the conductive loop is poor. When running at high current, the local temperature rise at the poor contact will increase, even leading to vicious circle and oxidation burning loss, so more attention should be paid to the circuit breaker used for high current operation. When measuring the loop resistance, the bridge method is not allowed, and the DC voltage drop method specified in GB763 must be adopted.
Extended data
maintain
Vacuum circuit breakers should be inspected and maintained once a year to ensure normal operation. Inspection should do the following work:
A) Carry out power frequency withstand voltage test on the pipe fracture, test the vacuum degree and record it.
B) Conduct power frequency withstand voltage test on insulation.
C) Test and record the opening distance, contact stroke and mechanical characteristics of the circuit breaker.
D) Check whether the connecting bolts and nuts of the adjustable position of the connector are loose, especially the connecting small screws at the crank arm of the auxiliary switch and the locking nuts connected with the movable conductive rod of the vacuum tube.
E) Check whether all kinds of snap rings and pins at each rotating joint are loose; And add lubricating oil paste to each rotating and sliding part.
F) For vacuum circuit breakers with current greater than 1 600 A, the DC resistance of each pole shall be tested and recorded.
G) If the pipeline needs to be replaced, it shall be carried out according to the requirements of the product manual. After replacement, mechanical characteristics and pressure tests should be carried out.
H) After the annual inspection and before the operation, it shall be continuously run at no-load for 8 ~ 10 times, and it can be put into operation only after everything is normal.
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