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ITGlossary · Protection and installation
Emergency Power Off (EPO)
A safety feature that allows immediate shutdown of power to connected systems in an emergency.
Technical level:Intermediate
It is a switch, usually a red mushroom-head button, or a contact wired to dedicated terminals on the UPS. When activated, the UPS shuts off its output immediately, even when running on battery. It is used in data centres, server rooms and industrial sites, often linked to the fire detection system or the building's main emergency button.
It matters a great deal for the safety of firefighters and technicians: a UPS keeps feeding its circuits even after the main switch on the distribution board has been turned off.
Check which contact type the UPS expects (normally open or normally closed): wrong wiring can shut down the entire load for no reason. Test the function during a scheduled window.
Related terms
- Auto RestartA UPS feature that automatically restarts the system after utility power returns following a shutdown.
- CCS2 (Combined Charging System)The European connector standard that adds two DC pins below a Type 2 plug, allowing fast DC charging through the same vehicle inlet.
- Cold Start FunctionA feature that allows a UPS to be started directly from the battery without utility power.
- Short CircuitAn unintended low-resistance connection between conductors that causes a sudden, dangerous surge of current.
- Altitude DeratingReduction in the rated power of a UPS, inverter or generator when it is installed above a certain altitude, usually 1,000 metres.
- Circuit ProtectionDevices such as fuses and circuit breakers that open the circuit on overcurrent or short circuit to prevent damage.