Detecting welded relay contacts using contact close time measurement

A method for detecting a welded relay contact, the method comprising:

• performing a weld detection check, comprising:
• closing a first relay and a second relay of a plurality of relays, wherein each relay of the plurality of relays comprises a first contact on an input side of the respective relay and a second contact on a load side of the respective relay, wherein the input side of each relay is coupled to a power source, and the load side of each relay is coupled to a load, wherein the load sides of each of the respective relays are coupled through their respective loads;
• measuring a first close time between the transmission of the close signal to the first relay and a time when the first relay closes;
• measuring a second close time between the transmission of the close signal to the second relay and a time when the second relay closes;
• and
• based on the first and second close times, determining whether an electrical weld exists in the first relay or the second relay.

A system, comprising:

• a relay system, comprising a relay having a first contact on an input side of the relay, the input side coupled to a power source, and a second contact on a load side of the relay coupled to a load;
• and
• a controller, comprising:
• one or more processors;
• and
• a memory having stored thereon instructions that, upon execution by the one or more processors, cause the one or more processors to perform a weld detection check comprising:
• transmit a close signal to the relay;
• measure a close time between the transmission of the close signal to the relay and a time when the relay closes;
• and
• determine that an electrical weld exists in the relay when the close time is less than a threshold, wherein the threshold is less than a close time of a non-welded relay.