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If you receive one of the Welded Relay errors on an XW Inverter/Charger (F17 through F22), it is possible that one of the AC transfer relays has failed, but in order to rule out wiring errors or improper operation of the AC bypass breakers, you should take the following steps:
First, verify that the AC Bypass Breakers are in the OFF position. If the AC Bypass breakers are switched ON while the Inverter Output breakers are also ON, the XW will sense that an AC voltage source is present on its AC Output terminals and will register one of these faults. The Power Distribution Panel (865-1015) comes prewired for a single XW and has an interlock to prevent both the Inverter Output breakers and the AC Bypass breakers from being both in the ON position. If installing multiple units, ensure that the AC breakers and interlock plate are installed per the installation manual to prevent this issue.
If the AC Bypass Breakers are off, power the inverter OFF at the AC and DC breakers and disconnect the AC wires from the Inverter's AC Out terminals at the inverter itself. Power the inverter back on and see if the fault clears.
If the fault clears, it is probable that the AC Input and output wires are crossed between the Power Distribution Panel and the Inverter/Charger. Verify the wiring, taking care in multiple inverter systems to ensure that the phases are not crossed (i.e. Line 1 breaker wired to Line 2 AC Input terminal or vice versa).
If the fault does not clear, it is likely a failure of one of the AC Transfer Relays. In this case, a replacement of the AC Board will be necessary. Contact Technical Support at 800-670-0707 following the RMA procedures in your Operation Manual.