AEC ACOA Series Air-Cooled Central Chillers - Manual (Page 42)

6 Electrical Devices
6-1 Control Circuit Power Switch - S1
This switch energizes the 115 VAC control circuit. Keep it on at all times (except for temporary
control circuit service work) to allow off-cycle pumpdown and normal on-cycle operation. The
compressor crankcase heater(s) is/are not affected by this switch.
6-2 Compressor Switch - S2, S3, S4, S5
This switch disconnects power from the corresponding compressor control circuit. Use these
switches during service only, since pumpdown is disabled when the switch is off.
6-3 Flow Switch - FLS
The chilled water flow switch assures chilled water flow while the ACOA chiller runs.
6-4 Chilled Water Pump Interlock - CWP
AEC/Application Engineering recommends that you install an interlock between the accessory
chilled water pump and the ACOA chiller package to prevent the chiller from operating with the
chilled water pump off. Connect the interlock to the terminals shown on the wiring diagram.
6-5 High Pressure Safety Switch - 1PS
Manual Reset
This switch stops the compressor if discharge pressure is too high. This condition can be caused
by fan failure or coil blockage.
6-6 Pumpdown Switch - 4PS
Auto Reset
This low pressure switch provides automatic recycling pumpdown in standby mode. It is
bypassed when the operating thermostat (
4TAS ) calls for the compressor to start.
ACOA Series Air-Cooled Central Chillers
Page 41