6
Chiller Components
Master Control Panel
Each chiller has a master control panel that can be mounted on top of any
of the module panels using provided knockouts. Sensors, cables and wiring
connect through the bottom of the master control. The master control box
includes built-in terminal strip inputs for flow switches, start/stop signal, alarm
output, and power phase monitor. As shipped, the Master Control also contains
the pLAN communication wire to be field installed by the start-up technician.
Four temperature sensors and sensor wells are supplied by Multistack: entering
chilled water, leaving chilled water, entering condenser water, and leaving
condenser water. The sensors are to be installed in customer’s piping system.
Module Control Boards and Low Voltage Panel
The module control boards communicate individual module temperatures
and pressures to the master control. Each module has a switch labeled Auto/
Off/ Manual. Normal operation is in the Auto mode. If there is a problem with
the master control, the selector switch can be changed to Manual to provide
individual module leaving chilled water temperature control that was pre-set
at the master control.
Module High Voltage Panel
The high voltage panel contains each compressor’s contactor, circuit breaker,
control relay and transformer. External to the panel is the single-module isola-
tion switch to isolate the that module from high voltage supply power.
Compressors, Sensors, Switches
• Standard modules use two scroll compressors with separate refrigeration
circuits.
• Each refrigerant circuit has a high pressure (HP) and low pressure (LP)
transducer that sends pressure signals to the module slave controller
board. Each compressor also includes an HP switch with a manual reset
button.
• Transducers are a 0-5V ratiometric type.
• Compressors include oil level sight glasses. Oil level should be at 1/8 - 1/4
full during operation.
• Each circuit has its own leaving chilled water temperature sensor and
refrigerant suction temperature sensor.
• Compressor crankcase heaters are not standard on Multistack MS chiller
modules.
Chilled and Condenser Water Connections
•
Water connections to the chilled and condenser side are standard 6-inch
grooved pipes on MS010X through 070X, and 8-inch on MS085X units.
• The upper header on the chilled water side is entering water to the
module.
• The bottom header is chilled water leaving the module.
• Water entering the condenser is on the bottom.
• Water leaving the condenser is on top.
• The entering header on both the evaporator and condenser contains a 30-
mesh filter strainer to prevent debris from entering the brazed plate heat
exchangers. This strainer should only be used as a final filter stage.
• Proper filtration before the module should be installed for easy access to
cleaning, such as a ‘Y’ or a basket type of strainer.
High Voltage Panel
A Compressor
Isolation Switch
Control
Relay Transformer
High Voltage
Circuit Breaker Control
Relay
B Compressor
Isolation
Switch
A Compressor
Contactor
B Compressor
Contactor
Single
Circuit
Breaker
Master Controller
AUTO/OFF/MANUAL
Switch
Module Slave
Controller
Low Voltage
Terminal Strips
Low Voltage
Circuit Breaker
Low Voltage Panel
