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ITGlossary · Electrical units
Isolation
Separation of input and output with no conductive connection, usually through a transformer, to protect against faults and noise.
Technical level:Intermediate
In practice, isolation is usually achieved with a transformer: energy passes magnetically from the primary to the secondary winding, with no direct conductive connection. This breaks ground loops, reduces common-mode noise and limits the transfer of faults from input to output.
Some UPS units, mainly industrial or medical ones, have a built-in or optional isolation transformer. In most modern transformerless UPS units the neutral passes straight from input to output, so there is no galvanic isolation.
Isolation matters when a new earthing system has to be created at the output, or when the equipment is particularly sensitive to noise. If you need it, check for it explicitly in the specifications, because not every UPS provides it.
Related articles
Related terms
- TransformerAn electrical component that changes voltage levels or isolates circuits.
- Hardwired (Terminal Block) ConnectionPermanent connection of the UPS input or output by an electrician, with cables screwed into a terminal block instead of plugs and sockets, usually on higher-power UPS units.
- Noise (Electrical)Unwanted high-frequency disturbances on the supply voltage, e.g. from motors or power supplies, which UPS systems and line conditioners filter out.
- Transformer-Based UPSTraditional UPS design using internal transformers to regulate voltage and provide isolation.
- Maintenance BypassA manual switch used to isolate the UPS for servicing while still supplying power to the load.
- IEC C13/C14 ConnectorsStandardised pair of connectors rated up to 10 A under IEC 60320, found on UPS outputs and on the power supplies of computers, servers and monitors.