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ITGlossary · Power quality
PDU (Power Distribution Unit)
A rack power strip that distributes UPS power to the equipment, optionally with metering or remote control.
Technical level:Basic
It is mounted horizontally, usually in a 1U slot, or vertically at the back of the rack, and connects to the UPS with an IEC C14, C20 or industrial plug. Outlets are typically IEC C13 and C19, which match server and switch power supplies.
Basic PDUs simply share out the power, metered ones show the load current, and managed ones let you switch each outlet on and off over the network. Metering helps avoid overloading either the PDU or the UPS. A common single-phase PDU is rated at 16 A.
For servers with dual power supplies, use two PDUs on independent feeds. A common mistake is connecting both to the same UPS, which defeats the redundancy.
Related terms
- ATS (Automatic Transfer Switch)A device that automatically moves the load from the grid to a generator during an outage and back again when grid power returns.
- Automatic Voltage Regulator (AVR)A device that automatically maintains a constant voltage level to protect electrical equipment from fluctuations.
- Electromagnetic Interference (EMI)Unwanted electrical noise or interference that can disrupt electronic equipment operation.
- Line ConditionerA device that improves power quality by regulating voltage and filtering noise.
- OvervoltageA voltage above normal that lasts from seconds to hours and can stress or damage connected equipment.
- Power ConditioningTechniques such as EMI/RFI filtering, surge protection and AVR that correct voltage problems before they reach the load.