Phase Protector (Optional) - McQuay SB250B Installation Manual

The unit with Scroll Compressor can only rotate in one direction. For this reason, a protective device (phase protector) is
fitted to prevent incorrect wiring of the electrical phases. When the three phases are not connected correctly, the phase
protector operates, and the unit will not start. This devise is located in the control box of the outdoor unit.
The following table shows the LED indicator light for phase protector under normal operation and fault conditions.
LED
Description
Normal operation
Reverse phase
T phase missing
S phase missing
R phase missing
+
S &T phase missing
+
Overload
Sensor missing +
ON
Notes: 1. "+" indicates additional functions for PP01 phase protector.
2. When R phase missing, no LED or buzzer will indicate the error, but relay 71 and relay 81 will cut off.

PHASE PROTECTOR (OPTIONAL)

PW P_R P_S
(Red) (Yellow) (Yellow)
OFF
!
• Troubleshooting must be performed by qualified personnel.
P_T
(Yellow)
Switch off the unit. Check the 3 phase wiring.
Switch off the unit. Check the 3 phase wiring.
Switch off the unit. Check the 3 phase wiring.
Switch off the unit. Check the 3 phase wiring.
Switch off the unit. Check the 3 phase wiring.
High discharge temperature. Check the refrigerant system.
Switch off the unit. Plug in sensor.
Fast Blink
Warning
1-14
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