Specifications

Catalog WSC/WDC-4 85
Main Control Relays
Redundant motor control relays with coils in parallel and contacts in series to interlock the
starter with the chiller. These two relays shall constitute the only means of energizing the
motor contractors. No other devices (manual or automatic) with the capability of
energizing the starter can be used. The starter is controlled by the unit microprocessor.
Motor Protection and Overloads
The starter shall include overload protection functions. These controls include:
• Solid state overload (overcurrent) protection
• Phase unbalance protection
• Phase reversal and phase loss protection.
• Adjustable overload to closely match motor performance
• Three current transformers to measure motor current and a fourth current transformer
for input to the chiller microprocessor.
Undervoltage (UV) Relay
The undervoltage relay is an adjustable three-phase protection system that is activated
when the voltage falls below a predetermined safe value and is factory set at 85% of
nominal.
Control Voltage Transformer
The starter is provided with a 3KVA control transformer with both secondary and primary
fuses to supply control power to the chiller.
Additional Standard Components
• Mechanical type solderless connectors to handle wire sizes indicated by the NEC.
• Three isolated vertical line contactors
• Three-pole, gang operated non-load break isolating switch
• Three vertically mounted current limiting power fuse blocks (fuses included)
• Magnetic three-pole, vacuum break contactor
• Single phase control circuit transformer
• Vertically mounted control circuit primary current limiting fuses
• Current transformers
• Load terminals
• Control circuit terminal blocks and secondary fuses
• Phase failure and reversal relay
G. CHILLER CONTROLLER
Base unit/compressor control is done through a 4-by-20-character display to view system
parameters, denote alarms and input setpoints.
In conjunction with the standalone base unit controller, the chiller manufacturer shall
supply a redundant, state-of-the-art
Operator Workstation, complete with super VGA
color touchscreen monitor, keyboard and USB port.
The operator workstation shall have inherent trend logging capabilities, which are
transferable to other PC management systems such as an Excel spreadsheet via a USB port.
Active trend logging data shall be available for viewing in 20 minute, 2 hour or 8 hour
intervals. A full 24 hours of history is downloadable via a USB port. The following
trended parameters shall be displayed:
• Entering and leaving chilled water temps
• Entering and leaving condenser water temps
• Evaporator saturated refrigerant pressure
• Condenser saturated refrigerant pressure
• Net oil pressure
• % rated load amps