5–11
T-340
5.11 Emergency Bypass Operation
Emergency Bypass operation is used to override the controller, in the case of a controller malfunction, to keep the unit
cooling. When Emergency Bypass is installed and turned on, the unit will remain in a continuous state of full cool until
the Emergency Bypass switch is turned off.
To place the unit in the Emergency Bypass Operation:
1. Locate the connection diagram and connectors for the emergency bypass (EB) sensors behind the top left
side of the compressor.
2. Disconnect the emergency bypass connector from the controller connector and attach it to the emergency
bypass module connector (see
).
3. Locate the wire tire located at the EB switch in the control box.
4. Cut the wire tie, then place the EB switch in the On position.
5. Place the Mode Switch (MS) in the Full Cool position to enable the system for cooling.
6. Manually control container air temperature by cycling the Mode switch between Full Cool and evaporator
Fans Only.
To operate the fans only, the MODE switch must be in the FANS ONLY position and the EMERGENCY BYPASS
switch must be in the Bypass position.
The EBS module uses the system’s safety devices (high pressure switch, motor internal protectors, and heat termi
-
nation thermostat) to protect the system while in Emergency Bypass Mode.
CAUTION
!
The unit will remain in the full cooling mode as long as the EB switch is in the On position and
the Mode Switch is in the Full Cool position. If the cargo can be damaged by low temperatures,
the operator must monitor container temperature and manually cycle operation as required to
maintain temperature within required limits.
When the Emergency Bypass switch is in the Bypass position, the EBS will be enabled.
With the Mode switch in Full Cool mode, the following will occur simultaneously:
a. The EBS switch will enable EBS input.
b. The phase detection circuit will detect the phase rotation and close to provide power to the compressor con
-
tactor.
c. The condenser fan contact will close to energize the condenser contactor and provide power to the con
-
denser fan motor.
d. The evaporator fan contact will close to energize the high speed evaporator contactor and provide power to
the evaporator fan motor.
e. The EBS electronic module will operate the EEV to control superheat.
To return the unit to normal operation:
1. Locate the connectors behind the compressor.
2. Disconnect the Emergency Bypass connector from the EBS module connector and reconnect it to the con
-
).
3. Inside the control box, place the EB switch in the Off position.
4. Re-install the wire tie at the switch mounting.
