In the case of MGE
UPS equipment, EPO means
emergency power off (or out). It is typically a
big red switch with a cover either on the UPS itself or on a wall in a
protective box. Or at my work, both.
EPO falls into the
scram switch category as it is not a normal
power down. Hitting the "off" switch on our MGE Comet will shut off line regulation, leaving the
loads powered, just not on clean power. Hitting EPO causes a deliberate short within the UPS, causing key
fuses to blow out and shutting down
everything.
Feasible reasons for pressing EPO are few and far between. It might be nice for
secure installations to be able to leave they're machines in a not-too-easy-to-start configuration in the event the
premise must be evacuated. Or maybe an outlet
shorted somehow and is
welding it's way back to the
circuit breaker. Perhaps you walked into the server room one morning and discovered a lake under the raised floor due to a leaky
air conditioner. Or
fire. These are EPO situations.
Use of the EPO switch is typically followed by scrambling
MIS personnel, and possibly use of fire extinguishers depending on the situation in which the EPO was hit. A call to MGE should follow shortly, since you've just disabled the UPS. An explanation for why you
murdered the UPS is probably in order as well.