Power distribution units (PDUs) have an electrical input and several outputs, often as electrical outlets, for powering multiple devices. They typically contain features such as circuit breakers and transient voltage suppression. Unit types can be modular or desktop, monitor shelf, plug strip, cabinet or cabinet mount, rack mount, vertical mount, wall mount, or hardwire mount. The number of outlets in the power strip or power distribution unit (PDU) also refers to the number of outputs if not in the form of AC outlets. Outlet configurations can be NEMA, IEC, CEE, or JIS.
Important electrical specifications to consider when searching for power distribution units (PDUs) include nominal voltages, frequency, phase, current rating, and power rating. Nominal voltages can be 24 VDC, 48 VDC, 115 VAC, 208 VAC, or 230 VAC. Frequency can be at 50Hz, 60Hz or 400Hz. 50Hz is common for European power. 60Hz is common in North American power. 400Hz is most widely used in aerospace applications. Phases can be single or three phase. Single phase is the standard AC Power for instrument, computers, etc. Three-phase power is used for medical and industrial power applications such as imaging systems drive motors, pumps, etc., where power efficiency and higher loads are critical considerations. Current rating is the rated current for the power distribution unit, typically given for maximum continuous current. The power rating is the total power rating for the PDU; includes all outlets and circuits. An important environmental operating parameter to consider is the operating temperature.