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ITGlossary · Electrical units
Hardwired (Terminal Block) Connection
Permanent 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.
Technical level:Intermediate
Beyond a certain size, the UPS current exceeds the 16 A that a Schuko plug or a C19 connector can carry. That is why larger single-phase and all three-phase UPS units have terminals for phase, neutral and earth, connected by a line from the distribution board with its own circuit breaker.
A terminal connection cannot be unplugged by accident and allows the correct cable cross-section and protection, so it is also preferred for smaller UPS units in critical installations. It does, however, require an electrician and adherence to the manual's instructions.
A frequent problem is loose terminals. Tighten them to the torque specified by the manufacturer and check them again at the first maintenance visit, because a loose connection heats up and can cause damage or fire.
Related terms
- 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.
- IEC C19/C20 ConnectorsPair of connectors rated up to 16 A under IEC 60320, used on higher-power UPS units, rack PDUs and servers or switches with high-consumption power supplies.
- Input Power CordThe cable that connects the UPS to the wall socket or distribution board, i.e. to its AC power source.
- IsolationSeparation of input and output with no conductive connection, usually through a transformer, to protect against faults and noise.
- 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.
- Peak LoadThe highest amount of power drawn by connected equipment during operation.