5.10 Optional Operating Modes; Emergency Bypass Operation - Carrier PrimeLINE Operation And Service Manual

In Frozen Mode, only the controlling probes are considered. Disagreement of the controlling probes can trigger a
defrost probe check, which will occur when the difference between the sensors is greater than 2.0°C (3.6°F).
Normally, the controlling probes are the return probes but if both return probes are invalidated, the supply probes
are used for control purposes. Probe disagreement of the non-controlling probe pair will not trigger a defrost probe
check.
If after the defrost probe check the supply probes agree and return probes agree, all supply and return sensors are
considered valid and the unit returns to normal control.
Probe Disagreement:
If the supply probes disagree and the return probes agree, the controller will invalidate the worst supply probe. If the
probe check is run as part of pre-trip P-5, an alarm will be triggered for the invalidated probe. If it is a run time defrost
probe check, the invalidated probe will be passed over and no alarm will be triggered. However, if the best supply
probe is greater than 1.2°C (2.2°F) difference with respect to its return probes, the best supply probe is also
invalidated. If unit is in Perishable Mode, a probe alarm will be triggered for both supply probes.
If the supply probes agree and the return probes disagree, invalidate the worst return probe. If the probe check is
being run as part of pre-trip P-5, an alarm will be triggered for the invalidated probe. If it is a run time defrost probe
check, the invalidated probe will be passed over and no alarm will be necessary. If the best return probe is greater
than 1.2°C (2.2°F) difference with respect to its supply probes, then the best return probe is also invalidated. If the
unit is in perishable mode, a probe alarm will be triggered for both return probes.

5.10 Optional Operating Modes

5.10.1

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
termination thermostat) to protect the system while in Emergency Bypass Mode.
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:
• The EBS switch will enable EBS input.
• The phase detection circuit will detect the phase rotation and close to provide power to the compressor
contactor.
T-362
Figure 5.3).
CAUTION
!
5–8