Control Sequence of Operation

Electrical Sequence

This section will acquaint the operator with the control logic governing CDHF/CDHG chillers equipped with Tracer CH530 UCP based control systems. When reviewing the step-by-step electrical sequences of operation, refer to the typical wiring schematics for Unit mounted Wye Delta starter shown in the installation manual shipped with the chiller.

Note: The typical wiring diagrams are representative of standard units and are provided only for general reference. They may not reflect the actual wiring of your unit. For specific electrical schematic and connection information, always refer to the wiring diagrams that shipped with the chiller.

With the supply power disconnect switch or circuit breaker (2Q1 or 2K3) closed, 115-volt control power transformer 2T5 and a 40-amp starter panel fuse (2F4 ) to terminal (2X1-1) starter panel to terminal 1X1-1 in the control panel. From this point, control voltage flows to:

1.Circuit Breaker 1Q1 which provides power to the starter module (2A1) relay outputs and the High Pressure Cutout switch (3S1).

2.Circuit Breaker 1Q2 which provides power to the Purge circuitry.

3.Circuit Breaker 1Q3 which provides power to Transformer (1T1) which steps down the 115 Vac to 24 Vac. This 24 Vac then powers the 24 Vdc power supply 1A1, and 1A2 if present. The 24 vdc is then connected to all modules via the Interprocessor communications Bus providing module power.

1Q3 also provides power to the external chiller water proof of flow device connected between terminal block 1X1-5 to 1A6-J3-2, and condenser water proof of flow device connected at 1X1-6 to 1A6- J2-2.

4.Circuit Breaker 1Q4 which provides power to the Oil Heater 4HR1 circuit and to circuit breaker 1Q5 oil and refrigerant pump circuits.

5.The DynaViewdisplay module 1A22, receives 24 vdc power from the IPC bus.

UCP and Wye-Delta Starter Control Circuits

Logic Circuits within the various modules will determine the starting, running, and stopping operation of the chiller. When operation of the chiller is required the chiller mode is set at ‘‘Auto’’. Using customer supplied power, the chilled water pump relay (5K1) is energized by the 1A5 Module output at 1A5-J2-4, and chilled water flow must be verified within 4 minutes 15 seconds by the 1A6 Module. The main processors logic decides to start the chiller based on the differential to start setpoint. With the differential to start criteria met module 1A5 then energizes condenser water pump relay (5K2) via customer supplied power at 1A5 J2-1.

Based on the restart inhibit function and the differential to start setpoint, oil and refrigerant pump (4M3) will be energized by 1A7 Module (1A7-J1). The oil pressure must be at least 9 Psid for 30 continuous seconds and condenser water flow verified within 4 minutes 15 seconds minutes for the compressor start sequence to be initiated.

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American Standard CH530 Control Sequence of Operation, Electrical Sequence, UCP and Wye-Delta Starter Control Circuits