What causes fault code VFD-RELAY1 (VFD Output Relay Fault — Relay Welded or Open)?

Relay contacts welded from switching inductive load without suppression — contactor coil, solenoid, etc.. Relay exceeded rated contact current — load current too high for relay rating (typically 2A). Relay mechanical wear — exceeded cycle life. Relay function programmed incorrectly — outputs unexpected state. Relay coil burned out — internal to VFD, may require board-level repair

How do I fix fault code VFD-RELAY1?

Check relay state with multimeter at relay output terminals — NO/NC/COM. Verify relay programming in VFD parameters — confirm assigned function. If relay is welded, you can hear/feel it not clicking when state changes — listen carefully. Add a snubber (RC network) across the relay contacts if switching inductive loads. If relay is built into VFD, use an external interposing relay driven by VFD digital output to isolate the load. Replace VFD relay board or use external relay as workaround

VFD Output Relay Fault — Relay Welded or Open

VFD-RELAY1

VFD programmable output relay is stuck closed (welded) or not operating. Relay used for fault indication, run status, or interlock feedback.

medium vfd

vfd relay output welded interlock

Probable Causes (ranked)

Relay contacts welded from switching inductive load without suppression — contactor coil, solenoid, etc.
Relay exceeded rated contact current — load current too high for relay rating (typically 2A)
Relay mechanical wear — exceeded cycle life
Relay function programmed incorrectly — outputs unexpected state
Relay coil burned out — internal to VFD, may require board-level repair

Fix Steps

1 Check relay state with multimeter at relay output terminals — NO/NC/COM
2 Verify relay programming in VFD parameters — confirm assigned function
3 If relay is welded, you can hear/feel it not clicking when state changes — listen carefully
4 Add a snubber (RC network) across the relay contacts if switching inductive loads
5 If relay is built into VFD, use an external interposing relay driven by VFD digital output to isolate the load
6 Replace VFD relay board or use external relay as workaround

Field Trick

VFD onboard relays are rated for about 100,000 operations at 2A. If your relay switches a contactor coil every 30 seconds, that's 2,880 operations per day — the relay lasts about 35 days. Use an external relay rated for higher current and cycle count.

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