Mae cyflenwad pŵer rac yn cyfeirio at y ddyfais cyflenwi pŵer sydd wedi'i gosod y tu mewn i'r rac neu ar bolyn cylched offer cyfathrebu. Mainly refers to the DC converter set up to meet the requirements of communication equipment for non basic power supply voltage; This also includes small switch type rectifiers and inverters

It generally consists of AC power supply system, DC power supply system, and grounding system, including power generation, transformation, nosbarthiadau, converter, and battery equipment. Communication equipment usually receives power from two automatically switched AC mains after rectification, with oil engine generators and batteries in a low current float charging state as backup; Places without mains power use oil powered generator sets, solar cells, etc. for power supply; Some communication devices also use remote power supply. The requirements for communication power supply are: reliable power supply, no instantaneous interruption allowed; The voltage is stable, and the harmonic components of the AC power supply and the pulsating components of the DC power supply must be lower than the allowable values; Efficiency should be high. With the miniaturization and integration of communication equipment, corresponding power supply equipment is also required to be miniaturized, modular, and intelligent. Ar hyn o bryd, switch regulated power supplies, acid proof and explosion-proof sealed maintenance free batteries, uninterrupted power supply systems, and decentralized power supply methods are widely used. The centralized monitoring and maintenance management automation of communication power supplies at various stations through microcomputer networking has become a development trend.