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Fig. 38 — 50BVC,E,Q020-034 Constant Volume Wiring Schematic
a50-8250
LEGEND
NOTES:
1. See unit nameplate for electrical rating.
2. All field wiring must be in accordance with NEC-NFPA #70.
3. 208/230-v units are factory wired for 208-v operation. For 230-v operation, remove ORG lead and replace
with RED lead. Cap all unused leads.
4. Check phase rotation on all scroll compressor units. Reverse rotation will damage the compressor and
void unit warranty.
5. For alternative EMS coil voltages, consult factory.
6. UPM board includes built in 30 to 60-second random start, 5-minute delay on break, 90-second low pres-
sure bypass, and 5-second second stage delay.
7. Setting the UPM board test mode jumper to yes reduces all time delays to 5 seconds.
8. “Freeze” pins on UPM board must be jumped if freeze sensor is not installed.
Standard Components Legend:
#1 — First Stage
#2 — Second Stage
BM — Blower Motor (1 or 2 per Unit)
BR — Blower Relay
CBR — 24-vac Circuit Breaker
CC — Compressor Contactor
CPM — Compressor Protection Module (15 Ton and Larger Compressors)
HPS — High Pressure Switch
LPS — Low Pressure Switch
RV — Reversing Valve
Optional Components Legend:
AUX — Auxiliary Relay (for Pumps, Valves, etc.)
BMR — Blower Motor Relay
CMFR — Compressor Malfunction Relay
CMR — Compressor Monitor Relay
CS — Condensate Sensor (One per Drain Pan)
EMS — Energy Management System Relay
FS — Freeze Sensor
HGL — Hot Gas Limit (Bypass Only)
PM — Phase Monitor
Factory Wire
Field Wire
TRANSFORMER PRIMARY
LEAD COLOR
120 White
208 Red
240 Orange
277 Brown
380 Purple or Yellow
460 Black/Red
575 Gray