Emerson 250-400kVA manual UPS controls monitor the DC Bus positive

			UPS Alarm and Status Messages
Table 7	Liebert NXL alarm and status messages (continued)
Event Message		Event Definition	Recommended Action
		The Controls Communication Failure event
		indicates a loss of communications between the
		Controls and Human Machine Interface (HMI).	If the alarm does not clear, or if the alarm condition
Controls		The Controls Communication Failure event is
		displayed when the HMI detects a loss of	returns, contact your factory-authorized service
Comm Fail
		communication with Controls on the Controller	provider.
		Area Network (CAN).
		An infrequent occurrence that resets immediately
		is probably not serious.
		This alarm means one or more critical settings
		have been changed by user during UPS
Controls Reset		operation.
		The change(s) will not take effect until after a UPS	Press “SILENCE” to silence the audible alarm.
Required
		Controls reset. This operation should only be
		performed by an authorized service personnel.
		This alarm is cleared after UPS Controls reset.
			Press “SILENCE” to silence the audible alarm.
			Press “RESET” to clear the fault.
		The negative DC Bus has a ground fault.	Perform a visual inspection of the batteries. Look for
		The UPS controls monitor the DC Bus negative	signs of leaking battery acid or excessively
		half for a voltage imbalance caused by current	corroded battery terminals.
		flow to ground. This fault means excessive	If there are no visible signs of defective batteries,
DC Link		ground current is detected.	open one Battery Breaker. Press “RESET” and see
		In normal operation, with the batteries connected,	if the condition clears. If the condition clears, you
Gnd Fault -
		the most likely cause of a current path to ground	have isolated the problem to that battery string.
		is a leaking battery.	If the condition will not clear, repeat the test with
		If your system includes an optional Battery	each connected battery string.
		Ground Fault Monitor, check if the Battery Ground	Once the location is identified, or if the battery string
		Fault message is present also.	tests are inconclusive, contact your factory-
			authorized service provider.
			Press “SILENCE” to silence the audible alarm.
		The positive DC Bus has a ground fault.	Press “RESET” to clear the fault.
			Perform a visual inspection of the batteries. Look for
		The UPS controls monitor the DC Bus positive
			signs of leaking battery acid or excessively
		half for a voltage imbalance caused by current
			corroded battery terminals.
		flow to ground. This fault means excessive
			If there are no visible signs of defective batteries,
		ground current is detected.
DC Link			open one Battery Breaker. Press “RESET” and see
		In normal operation, with the batteries connected,
Gnd Fault +		the most likely cause of a current path to ground	if the condition clears. If the condition clears, you
			have isolated the problem to that battery string.
		is a leaking battery.
			If the condition will not clear, repeat the test with
		If your system includes an optional Battery
			each connected battery string.
		Ground Fault Monitor, check if the Battery Ground
			Once the location is identified, or if the battery string
		Fault message is present also.	tests are inconclusive, contact your factory-
			authorized service provider.
			Press “SILENCE” to silence the audible alarm.
		An Emergency Module Off (EMO) command has	Resolve the issue that precipitated the EMO.
			For safety, the UPS latches an EPO event. To clear
		been detected.
			the latch, press the EMO Reset pushbutton on the
		The EMO signal means the front panel EMO
			External Interface Board (EIB).
EMO Shutdown		button was pressed. A Remote EMO would
			Verify the EMO is cleared by pressing “RESET” and
		display the “REMO Shutdown” alarm.
			observing that the EPO alarm in the Active Event
		In response to an EMO, the UPS transfers to
			Window is gone.
		Bypass and shuts off.
			Restart the UPS by pressing “Startup,” “Manual
			Start,” and follow the prompts.

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