What causes fault code VFD-PL1 (VFD Input Phase Loss)?

Input fuse blown on one phase — check all three. Loose wire on one phase of the input terminal block. Upstream breaker has a weak pole — trips one phase intermittently. Supply transformer has an open winding on one phase. Contactor feeding drive has one bad contact

How do I fix fault code VFD-PL1?

Measure all 3 input voltages at drive terminals — all should be within 3%. Check and tighten all input terminal connections. Test all input fuses with a meter — not visual, blown fuses can look intact. Inspect contactor contacts — look for pitting, measure contact resistance. If breaker suspected, load-test each pole or replace breaker. Check upstream connections at MCC or panel board

VFD Input Phase Loss

VFD-PL1

Drive detected loss of one or more input power phases. Single-phasing causes DC bus ripple and potential damage.

high vfd

vfd phase loss single phase power fuse

Probable Causes (ranked)

Input fuse blown on one phase — check all three
Loose wire on one phase of the input terminal block
Upstream breaker has a weak pole — trips one phase intermittently
Supply transformer has an open winding on one phase
Contactor feeding drive has one bad contact

Fix Steps

1 Measure all 3 input voltages at drive terminals — all should be within 3%
2 Check and tighten all input terminal connections
3 Test all input fuses with a meter — not visual, blown fuses can look intact
4 Inspect contactor contacts — look for pitting, measure contact resistance
5 If breaker suspected, load-test each pole or replace breaker
6 Check upstream connections at MCC or panel board

Field Trick

Clamp each phase at the drive input with a current meter. The missing phase will read zero or near-zero amps.

Suggested Replacement Parts

Parts matched to fault category: Fuse

Bussmann FRN-R-30 Time-Delay Fuse P/N: FRN-R-30 30A, 250V, Class RK5, dual element time-delay

AutomationDirect $8.00 Amazon $6.50 Grainger $10.00 McMaster-Carr $9.00

Bussmann FRN-R-15 Time-Delay Fuse P/N: FRN-R-15 15A, 250V, Class RK5, motor circuit protection

AutomationDirect $7.00 Amazon $5.50 Grainger $9.00

Prices are estimates. Verify part numbers match your equipment before ordering.

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