30 McQuay IM 937
Control Panel Components
Figure 30: Circuit Breaker
Field Wiring Terminals
All field wiring terminals are spring clamp type, which offer
several advantages over traditional screw-type terminals:
• Spring connections do not require torquing
• Spring connections resist failure due to vibration
• Easily identifiable terminal markers
• Combination spring release and square test ports
Wire connections require inserting (“1” in Figure 31) a
stripped wire a round port and clamping the stripped wire by
inserting a flat-bladed screw driver in the adjacent square port
(“2” in Figure 31).
Figure 31: Terminal Connectors
Phase Voltage Monitor (PVM)
The phase voltage monitor (Figure 32) is designed to protect
three-phase loads from damaging power conditions. A
microprocessor-based voltage and phase sensing circuit
constantly monitors the three-phase voltages to detect harmful
power line conditions. When a harmful condition is detected,
its output relay is deactivated after a specified trip delay (Trip
Delay). The output relay reactivates after power line
conditions return to an acceptable level for a specified amount
of time (Restart Delay). The trip and restart delays prevent
nuisance tripping due to rapidly fluctuating power line
conditions.
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