Emerson user manual Liebert FPC, +24VDC, Unit EPO, Main, Source Input Breaker, Shunt, Trip

Installation Instructions

1.3.6Control Wiring Connections

NEC Article 645 requires that emergency power off (EPO) switches be located at the principal room exits. All standard Liebert power conditioning systems have provisions for external shutdown control from Remote Emergency Power Off (REPO) stations. Figure 14 is a simplified diagram of the shut- down circuitry of the Liebert FPC.

Low-Voltage Control Circuit

Control wiring connections must comply with the NEC and all other applicable codes.

! WARNING

Verify that all incoming high-voltage (power) and low-voltage (control) circuits are de-energized and locked out before installing cables or making connections, whether in the junction box or in the unit.

As shown in Figure 14, the control circuit operates on 24VDC. The shutdown device (represented by the REPO switch) activates a low-current, 24VDC relay that in turn operates the shunt-trip mecha- nism. The shunt-trip solenoid opens the Main Input Breaker, which de-energizes the power center.

Multiple-Unit Shutdown

When more than one power center is installed by the user, a typical requirement is that actuation of a single device (REPO for example) must shut down all power centers. The low-voltage control circuits of all standard Liebert FPC systems are designed to meet this requirement.

External Control Wiring Connections

External control wiring connections for remote shutdown, alarm, and/or monitoring are made to the low-voltage junction box (if used) or to the low-voltage control terminal strip located inside the unit.

Control wiring connections vary with the type of monitoring system furnished with the unit. Two typ- ical control wiring configurations are shown in Figures 15 and 16.

Figure 14 Simplified shutdown circuit

	Liebert FPC			Remote
				Shutdown
		+24VDC	1	Devices
K5	K6
		Unit EPO	4
+
24VDC	Main			N.O. REPO
Source	Input	K6	6
-	Breaker	Overtemp		N.C. REPO
	Shunt	Switch
	Trip	K5	2
				A	7	4	1
			3				Building
							Interface
				R1			Relay
				B	9	6	3

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