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System Pumps
Operation of the chilled water pump can be to 1) cycle the pump with the compressor, 2) operate
continuously, or 3) start automatically by a remote source.
The cooling tower pump must cycle with the machine. The holding coil of the cooling tower
pump motor starter must be rated at 115 volts, 60 Hz, with a maximum volt-amperage rating of
100. A control relay is required if the voltage-amperage rating is exceeded. See the Field Wiring
Diagram on page 33 or in the cover of control panel for proper connections.
All interlock contacts must be rated for no less than 10 inductive amps. The alarm circuit
provided in the control center utilizes 115-volts AC. The alarm used must not draw more than 10
volt amperes.
See OM CentriMicro II for MicroTech II unit controller details.
Control Panel Switches
Three On/Off switches are located in the upper left corner of the main Unit Control Panel, which
is adjacent to the operator interface panel, and have the following function:
•
UNIT shuts down the chiller through the normal shutdown cycle of unloading the
compressor(s) and provides a post-lube period.
•
COMPRESSOR one switch for each compressor on a unit, executes an immediate shutdown
without the normal shutdown cycle.
•
CIRCUIT BREAKER disconnects optional external power to system pumps and tower fans.
A fourth switch located on the left outside of the Unit Control Panel and labeled EMERGENCY
STOP SWITCH stops the compressor immediately. It is wired in series with the COMPRESSOR
On/Off switch.
Surge Capacitors
All units (except those with solid state starters or VFDs) are supplied with standard surge
capacitors to protect compressor motors from electrical damage resulting from high voltage
spikes.
•
For unit-mounted starters, the capacitors are factory-mounted and wired in the starter
enclosure.
•
For free-standing starters, the capacitors are mounted in the motor terminal box and must be
connected to the motor terminals with leads less than 18 inches (460 mm) long when the
motor is being wired.
NOTES for Following Wiring Diagram
1. Compressor motor starters are either factory mounted and wired, or shipped separate
for field mounting and wiring. If provided by others, starters must comply with Daikin
specification 359AB99. All line and load side power conductors must be copper.
2. If starters are freestanding, then field wiring between the starter and the control panel is
required. Minimum wire size for 115 Vac is 12 GA for a maximum length of 50 feet. If
greater than 50 feet, refer to Daikin for recommended wire size minimum. Wire size for
24 Vac is 18 GA. All wiring to be installed as NEC Class 1 wiring system. All 24 Vac
wiring must be run in separate conduit from 115 Vac wiring. Main power wiring
between starter and motor terminal is factory-installed when units are supplied with
unit-mounted starters. Wiring of free-standing starter must be wired in accordance with
NEC and connection to compressor motor terminals must be made with copper wire
and copper lugs only. Control wiring on free-standing starters is terminated on a
D-EIMWC00804-14EN
Centrifugal Chillers
31
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