Sinclair SCV-750EB Service Manual page 145

6.5 L30: Low bus voltage protection
Description
The bus voltage is lower than the low bus voltage protection threshold (350VDC) 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 lower than the low bus voltage protection threshold (350VDC) 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 higher than the low bus voltage protection threshold (350VDC) (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 low, resulting in low bus voltage;
The voltage drop and interrupt, resulting in the low instantaneous bus voltage;
The module board bus voltage detection circuit is abnormal.
Procedure
Report error while in standby
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 low
Driver board precharge PTC overheating
L30
NO
NO
NO
Fault while running
1. The voltage drop and interrupt, need to
rectify the power supply
Yes
2. The unit shares power with high-power
electrical appliances, need to rectify the
Yes
Change the drive board
Yes
Rectify the power supply
Power off and wait for 5 minutes, wait for PTC to
Yes
cool down and power on again
power supply
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