Control Center - McQuay SWP Series Installation And Maintenance Manual

Electrical Data
Supply Power Wiring
Units require three-phase power supply.
1
Allowable voltage tolerances:
2
60 Hertz
a
Nameplate 208 V: Min. 187 V, Max. 229 V
Nameplate 230 V: Min. 207 V, Max. 253 V
Nameplate 460 V: Min. 414 V, Max. 506 V
Nameplate 575 V: Min. 518 V, Max. 632 V
50 Hertz
b
Nameplate 400 V: Min. 342 V, Max. 418 V
Power lead wire sizing:
3
For units with cooling capability (all concurrent loads)
a
with or without hot water heating and circuits with
motor loads only:
MCA = 1.25 (largest motor RLA or FLA) + other loads
+ 2 amps
For units with cooling capability and nonconcurrent
b
electric heat capability:
In the cooling mode, the loads are composed of supply
fan motor and compressors. In heating mode, the
loads are composed of supply fan motor and electric
heater. The MCA is calculated for unit running in
either mode; the highest value obtained is used for the
MCA.
– For unit in cooling mode:
MCA = 1.25 (largest RLA or FLA) + other loads + 2
amps
– For unit in heating mode, below 50 kW
MCA = 1.25 (electric heat FLA + fan FLA) + 2 amps
– For unit in heating mode, above 50 kW
MCA = 1.25 (SAF amps) + (electric heat) + 2 amps
Size wires in accordance with Table 310-16 of the National
4
Electrical Code.
Size wires for a maximum of 3% voltage drop.
5
16
Lug Sizes
Table 10: Lug Sizes for Single Disconnect
DIsconnect size (amps)
100
150
250
400
600
Table 11: Lug Sizes for Power Block
Power block size (amps)
420
760
Note: Use copper wire only.

Control Center

All electrical controls are enclosed in a central control center
located at the front of the unit. High voltage components
include:
• Fan motor contactor, M30/M10
• Fan motor protector, MMP9, MMP10, MMP30
• Fan motor circuit breaker, CB10
• Compressor contactors, M1–M6
• Compressor protector, MMP1–MMP6
• Electric heat contactors, M11–M16
• Transformer, T1, T2, T3
• Disconnect switch, DS1–DS2
• Power block, PB1–PB2
If the optional disconnect switch is provided, the switch handle
is visible and accessible without removing any safety or access
panels.
Low voltage components include:
®
• MicroTech III main control board, MCB
®
• MicroTech III expansion modules
• Duct static pressure sensor, SPS1
• Optional 2nd duct static pressure sensor, SPS2
®
• Optional BACnet /IP communication module
• Optional BACnet MS/TP communication module
®
• Optional L W communication module
ON ORKS
Located on the face of the unit is the interactive MicroTech III
keypad/display, unit switch, system indicator light and power
indicator.
IM 919 has additional layouts of the control center.
Note:
Lug size
#14-1/0
#8-3/0
3/0-350 MCM
(2) #4-250 MCM
(3) 3/0-500 MCM
Lug size
#2-600 MCM
(2) #4-500 MCM
McQuay IM 937