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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 terminal strip in the motor terminal box (not the unit control panel). Wiring from the unit
control panel to the motor terminal is done in the factory.
3.
For optional sensor wiring, see unit control diagram. It is recommended that DC wires be run separately from
115 Vac wiring.
4.
Customer furnished 24 or 120 Vac power for alarm relay coil can be connected between UTB1 terminals 84
power and 51 neutral of the control panel. For normally open contacts, wire between 82 & 81. For normally
closed contacts, wire between 83 & 81. The alarm is operator programmable. The maximum rating of the
alarm relay coil is 25 VA.
5.
Remote on/off control of unit can be accomplished by installing a set of dry contacts between terminals 70
and 54.
6.
Evaporator and condenser paddle type flow switches or water pressure differential switches are required and
must be wired as shown. If field supplied pressure differential switches are used then these must be installed
across the vessel and not the pump.
7.
Customer supplied 115 Vac, 20 amp power for optional evaporator and condenser water pump control power
and tower fans is supplied to unit control terminals (UTBI) 85 power / 86 neutral, PE equipment ground.
8.
Optional customer supplied 115 Vac, 25 VA maximum coil rated chilled water pump relay (EP 1 & 2) can be
wired as shown. This option will cycle the chilled water pump in response to building load.
