Specifications
80
* CHILLED
WATER
PUMP
STARTERS
EWI-2
CP2
CP1
NOTE 11
NOTE 11
NOTE 11
*NOTE 8
NOTE 8
NOTE 9
H
O
A
C4
* COOLING
TOWER
FIRST
STAGE
STARTER
* COOLING
TOWER
SECOND
STAGE
STARTER
* COOLING
TOWER
THIRD
STAGE
STARTER
* COOLING
TOWER
FOURTH
STAGE
STARTER
*
NOTE 10
H
A
O
C3
*
NOTE 10
H
A
O
NOTE 10
NOTE 10
79
78
77
74
73
* REMOTE
ON/OFF
(NOTE 5)
54
86
86
C
CWI-2
CWI-1
(115V) (24V)
MICROTECH CONTROL
BOX TERMINALS
55
70
H
A
O
H
A
O
H
O
A
C
H
O
A
C
H
O
A
C
NOTE 11
NOTE 9
EWI-1
C2
C1
*
*
*
*
*
*
UTB1
MODE SWITCH
EF1
76
75
PE
85
86
POWER
NEUTRAL
NOTE 7
*
* CONDENSE
R
WATER
PUMP
STARTERS
EP2
EP1
GND
EVAP.
FLOW OR
DELTA P
SWITCH
(NOTE 6)
COND.
FLOW OR
DELTA P
SWITCH
(NOTE 6)
71
71
53
52
81
84
COMMON
POWER
A
82(NO)
83(NC)
NOTE 4
*
0-10 VDC
0-10 VDC
*COOLING TOWER VFD
*ALARM RELAY
(NOTE 4)
*COOLING TOWER BYPASS VALUE
CF1
EF2
CF2
Figure 23, Field Wiring Diagram
1. Compressor terminal boxes are factory-mounted and wired. All
line-side wiring must be in accordance with the NEC and be
made with copper wire and copper lugs only. Power wiring
between the terminal box and compressor terminals is factory
installed.
6. If field supplied pressure differential switches are used, they must
be installed across the vessel and not the pump. They must be
suitable for 24vac and low current application.
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 (UTB1) 85 power / 86
neutral, PE equipment ground.
2. Minimum wire size for 115 VAC is 12 ga. for a maximum length
of 50 feet. If greater than 50 feet refer to McQuay 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.
Wiring must be wired in accordance with NEC and connection to
be made with copper wire and copper lugs only..
8. Optional customer supplied 115 VAC, 25 VA maximum coil rated,
chilled water pump relay (ep1 & 2) may be wired as shown. This
option will cycle the chilled water pump in response to chiller
demand.
9. The condenser water pump must cycle with the unit. A customer
supplied 115 VAC 25 VA maximum coil rated, condenser water
pump relay (CP1 & 2) is to be wired as shown. Units with free-
cooling must have condenser water above 60°F before starting.
3. Voltage unbalance not to exceed 2% with a resultant current
unbalance of 6 to 10 times the voltage unbalance per NEMA MG-
1, 1998 Standard
4. A customer furnished 24 or 120 Vac power for alarm relay coil
may be connected between UTB1 terminals 84 power and 81
neutral of the control panel. For normally open contacts wire
between 82 & 81. For normally closed wire between 83 & 81. The
alarm is operator programmable. Maximum rating of the alarm
relay coil is 25 VA.
10. Optional customer supplied 115 VAC 25 VA maximum coil rated
cooling tower fan relays (C1 - C2 standard, C3-C4 optional) may
be wired as shown. This option will cycle the cooling tower fans in
order to maintain unit head pressure.
11. Auxiliary 24 VAC rated contacts in both the chilled water and
condenser water pump starters must be wired as shown.
5. Remote on/off control of unit can be accomplished by installing a
set of dry contacts between terminals 70 and 54.
12. 4-20 mA external signal for chilled water reset are wired to
terminals 71 and 51 on the unit controller; load limit is wired to
terminals 71 and 58 on the unit controller.
Catalog WMC-4 37