Patent ID: 9581648
Date: 2017-02-28
CPC Classifications: G01R,H01H

Claim:
1. A relay welding detector adapted for detecting welding fault of a relay that is coupled between an alternating current (AC) power source and a load, the AC power source having a grounded earth terminal and a neutral terminal coupled to the earth terminal, the relay having a first electrical contact coupled to the neutral terminal of the AC power source through a first power line, and a second electrical contact coupled to the load through a second power line, said relay welding detector comprising: a signal generator for generating a test signal; a current transformer coupled to said signal generator for receiving the test signal therefrom, configured to generate an induced signal based on the test signal, and adapted to be wound with a portion of one of the first and second power lines; and a determining unit coupled to said current transformer, wherein said determining unit is configured to pre-store a predetermined threshold value, and is further configured to compare an amplitude of the induced signal from said current transformer with the predetermined threshold value, and is further configured to determine, based on a result of the comparison, whether the first and second electrical contacts of the relay are welded to each other; wherein said determining unit determines that said first and second electrical contacts of said relay are welded to each other when the result of the comparison indicates that the amplitude of the induced signal is smaller than the threshold value.