Sinclair SCV-1400EB, Service Manual

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140
6.2 L10: Hardware overcurrent
Description

The current exceeds the OCP protection value (peak value) set by the hardware or receives the FO signal from the IPM
module.

After the fault, the compressor stops running. If the fault disappears after one minute, the compressor starts again.
Trigger/resume condition

The current reaches the OCP protection value
Trigger condition: The current reaches the OCP protection value.
Resume condition: The compressor shuts down after a fault, and resumes after reaching the fault exit condition one minute
later.
Reset method: Automatic recovery after reaching the fault exit condition one minute later.

A falling edge or continuously low level of the FO signal is detected:
Trigger condition: The falling edge or continuously low electrical level of the FO signal is detected.
Recovery Condition: The FO signal turns into high level.
Reset method: Automatic recovery after reaching the fault exit condition one minute later.
Possible causes

There are impurities in the refrigerant system or the compressor is momentarily stuck, causing the current surge to trigger
OCP;

The compressor winding is short-circuited between phases, resulting in instantaneous high current to trigger OCP or FO;

The voltage of the system power supply drops or is interrupted for a short time, resulting in an instantaneous surge of
current to trigger OCP;

Condensation of the IPM module leads to a short circuit between the control pins;

System backflow;

The rotor has a certain speed when the compressor is started (commonly when a compressor has been started or the main
engine has been started, and the refrigerant drives the rotor of the compressor that is about to start when the four-way
valve is reversed);

The abnormality of the module board (Idc, OCP comparison circuit, PWM circuit, IPM, IGBT drive power circuit) causes the
control to lose step and generate a large current to trigger the OCP.
Procedure
L10
Report error while in standby
Yes
Change the drive board
NO
Compressor winding and insulation failure
Yes
Change the compressor
NO
Drive board fault(swap the drive board to judge)
Yes
Change the drive board
NO
Impurities in the refrigerant system or the
compressor is momentarily stuck (noise when
running or starting)
Yes
Change the compressor and
clean the system
NO
Whether the unit shares power with high-power
electrical appliances
Yes
Rectify the power supply