Sinclair SCV-750EB Service Manual page 147

6.7 L32: Excessively high bus voltage error
Description
The bus voltage is higher than the excessively high bus voltage protection threshold (770VDC) set by the software.

After the fault, the compressor stops running, and if the fault disappears after one minute, the compressor starts again.

Trigger/resume condition
Trigger condition: The bus voltage is higher than the excessively high bus voltage protection threshold set by the software.

Resume condition: The compressor shuts down after a fault, and resumes after reaching the fault exit condition (The bus

voltage is lower than the excessively high bus voltage protection threshold set by the software.) one minute later.
Reset method: Automatic recovery after reaching the fault exit condition one minute later.

Possible causes
The input voltage is too high, resulting in high bus voltage;

 The grid voltage is abnormally high instantaneously
 The module board bus voltage detection circuit is abnormal.
Procedure
The corresponding relationship between the
three-phase input power supply of the driver board
and the PN voltage does not match
Three-phase input power is too high
6.8 L34: Phase loss error
Description
The power input phase is missing or the three-phase power supply is seriously unbalanced.

After the fault, the compressor stops running, and if the fault disappears after one minute, the compressor starts again.

Trigger/resume condition
Trigger condition: The power input phase is missing or the three-phase power supply is seriously unbalanced.

Resume condition: Detect the factors that cause the phase loss, such as poor power input wiring or the screw of the

terminal is not tightened, or disconnect other electrical equipment that shares the power supply with the unit.
 Reset method: Automatic recovery after reaching the fault exit condition one minute later.
Possible causes
Abnormal system power wiring leads to phase loss, or the N line and the phase line are reversed;

The system power cord is poorly wired or the screws are not tightened;

The module board is abnormal (one-phase relay is not operating);

There is a large load on one or two phases of the system power supply, resulting in an unbalanced supply voltage;

The power distribution phase unbalance degree exceeds 3% (phase angle unbalance, or three-phase voltage unbalance, or

both).
L32
Report error while in standby
NO
NO
Fault while running
1. The voltage drop and
interrupt, need to rectify the
Yes
power supply
2. The unit shares power with
high-power electrical appliances,
need to rectify the power supply
Yes
Change the drive board
Yes
Rectify the power supply
145