Relay welding detector, relay equipment incorporating the same, and relay welding detecting method

A relay equipment adapted to be 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, said relay equipment comprising:

• a relay having a first electrical contact adapted. to be coupled to the neutral terminal of the AC power source through a first power line, and a second electrical contact adapted to be coupled to the load through a second power line;
• and
• a relay welding detector including
• 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 for determining, based on the induced signal from said current transformer, whether said first and second electrical contacts of said relay are welded to each other.

A relay welding detecting method for detecting, using a relay welding detector, 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, the relay welding detector including a signal generator, a current transformer coupled to the signal generator and wound with a portion of one of the first and second power lines, and a determining unit coupled to the current transformer, said relay welding detecting method comprising the steps of:

• (A) generating, by the signal generator of the relay welding detector, a test signal;
• (B) generating, by the current transformer of the relay welding detector, an induced signal based on the test signal;
• and
• (C) determining, by the determining unit of the relay welding detector, based on the induced signal, whether the first and second electrical contacts of the relay are welded to each other.