Operating Instructions
53
Unit Protection Devices
1. Main Circuit: A 25 ampere manual reset
circuit breaker protects the 460/380V power
supply circuit to the unit electric motors and
control system transformer. The main power
circuit breaker is located in the control box.
2. Control System Circuit: A 7 ampere circuit
breaker or a 7 ampere ATO fuse protects the
29 Vac control circuit. The circuit breaker is
located in the control box beside the ON/OFF
switch. The ATO fuse is located inside the
control box on the right side wall.
3. Fuses: A number of fuses are located on the
main relay board and controller to protect unit
circuits and components.
• A 2 amp fuse protects the controller’s
28 Vac system.
• A 2 amp fuse protects the controller’s
battery charging circuit.
4. Compressor Discharge Gas Temperature
Sensor: A refrigerant injection system uses the
compressor discharge temperature to
determine when cold refrigerant will be
injected into the center scroll of the
compressor to protect the compressor from
excessively high operating temperatures.
a. Chill Mode Liquid Injection:
• Controller energizes the liquid
injection valve when compressor
discharge gas temperature increases to
118 to 138 C (244 to 280 F)
• Controller de-energizes the liquid
injection valve to stop liquid injection
when the discharge gas temperature
decreases to 132 C (270 F).
NOTE: Controller also energizes the liquid
injection valve when cooling capacity is 83%
or less. Controller de-energizes the valve
when cooling capacity is 84% or more.
b. High Temperature Protection: The
controller immediately stops unit
operation if the discharge gas temperature
increases to 148 C (298 F). The controller
activates the Alarm LED and records
Alarm 56 (Compressor Temperature Too
High). The controller restarts the unit
when the condition corrects itself.
1. 28 Vac Control Circuit Fuse, 2 ampere
2. Battery Charging Circuit Fuse, 2 ampere
Figure 20: Control Circuit Fuses
AXA0240
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