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UPS for 480 Vac Grid, User Guide, doc. rel.4.0
5.
(Manual) Emergency Power Off – EPO
An external Emergency Power Off (EPO) switch may be installed on the UPS by the customer. The
EPO switch is used to cut power to the load in emergency situations. The switch or push button
must be a normally open type.
The UPS can be wired to trip the ac and dc breakers if they are equipped with a 48 V trip coil. This
can be used to cut all power from the grid and external battery banks to the UPS.
For detailed information, refer to the UPS Installation Guide of the system.
5.1.
EPO indication
Any of the output dry contacts can be assigned to indicate when the EPO switch has been
activated. The output dry contact can be used to trigger an external circuit if desired, such as a
lamp or an audible alarm. The LCD displays a shutdown by EPO and provides a visual and audible
indication.
5.2.
Battery trip coil dry contact
The UPS’s trip coil terminals are intended to be connected in series to the trip coil of the battery
circuit breaker. When this is done and the EPO switch is activated, the UPS closes a relay that can
be combined with a voltage source to activate the battery trip coil, causing the battery circuit
breaker to turn OFF. If the battery circuit breaker trip coil is rated for 48 Vdc, the power supply
can be provided directly by the UPS.
Use of the battery trip coil means that not only will use of the EPO switch cut all ac output from
the UPS, it will also switch off the battery circuit breaker.
For additional information, refer to the Battery Trip Coil section in the UPS
Installation Guide.
