FAULT
Message Possible cause Action
HW Con. Fail
(F26)
1. Power line is disconnected
inside the inverter
2. Current feedback circuit is
defective
1. Check the power lines inside the inverter
2. Check the current feedback circuit inside
the inverter
RCMU Fail
(F27)
1. RCMU is disconnected
2. Detection circuit malfunction
1. Check the RCMU connection inside the
inverter
2. Check the detection circuit inside the
inverter
1. One or more relays are
sticking
2. The driver circuit for the
relay malfunction
1. Replace the defective relay(s)
2. Check the driver circuit inside the inverter
1. One or more relays are
abnormal
2. The driver circuit for the
relay malfunction
3. The detection accuracy is
not correct for Vgrid and Vout
1. Replace the defective relay(s)
2. Check the driver circuit inside the inverter
3. Check the Vgrid and Vout voltage detect
on accuracy
RLY Short
(F28)
RLY Open
(F29)
Bus Unbal.
(F30)
1. Not totally independent or
parallel between inputs
2. PV Array short to Ground
3. Driver for boost is defective
or disconnected
4. Detection circuit malfunction
1. Check the inputs connections
2. Check the PV Array insulation
3. Check the driver circuit for boost inside
the inverter
4. Check the detection circuit inside the
inverter
HW Bus OVR
(F31, F33, F35)
1. Driver for boost is defective
2. Voc of PV array is over
1000Vdc
3. Surge occurs during
operation
4. Detection circuit malfunction
1. Check the driver circuit for boost inside
the inverter
2. Modify the solar array setting, and make
the Voc less than 1000Vdc
3. N/A
4. Check the detection circuit inside the
inverter
AC Cur. High
(F36, F37, F38,
F39, F40, F41)
1. Surge occurs during
operation
2. Driver for inverter stage is
defective
3. Switching device is defective
4. Detection circuit malfunction
1. N/A
2. Check the driver circuit in inverter stage
3. Check all switching devices in inverter
stage
4. Check the detect circuit inside the inverter
HW CT A Fail
(F42)
1. Test current loop is broken
2. CTP3 is defective
3. Detection circuit malfunction
1. Check the connection of CNP4 to CNM4
2. Replay CTP3 with new one
3. Check the detection circuit inside the
inverter
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Error message and Trouble Shooting