Detecting welded relay contacts using spanner voltage measurement

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

• performing a weld detection check, comprising:
• measuring a voltage between a spanner of a first relay of a plurality of relays and an input side of a second relay of the plurality of relays, resulting in a measured voltage, wherein each relay of the plurality of relays comprises a first contact on an input side of the respective relay coupled to a corresponding phase of a multi-phase power source that differs relative to each phase coupled to each other relay of the plurality of relays, a second contact on a load side of the respective relay coupled to a load, a spanner configured to close the first and second contacts of the respective relay when activated by a close signal, and wherein the load side of the respective relay is coupled to a load side of each other relay of the plurality of relays;
• and
• based on the measured voltage, determining whether an electrical weld of the first contact of the first relay exists.

A system, comprising:

• a relay system, comprising a plurality of relays, wherein each respective relay of the plurality of relays comprises a double-break relay and has a first contact on an input side of the respective relay, the input side coupled to a power source, a second contact on a load side of the respective relay coupled to a load, and a spanner configured to close the first and second contacts of the respective relay when activated by a close signal, and wherein the respective relay is coupled to a load side of each other relay of the plurality of relays through the load sides of the respective relay;
• 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;
• wherein, to perform the weld detection check, the instructions direct the one or more processors to:
• measure a voltage between a spanner of a first relay of the plurality of relays and an input side of a second relay of the plurality of relays, resulting in a measured voltage;
• and
• based on the measured voltage, determine whether an electrical weld of the first contact of the first relay exists.