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Generator Ratings

The connection procedures for generation depend on the aggregate rating of the generation at each premises. The aggregate rating of the generation is deemed to be the sum of the rating of each generator at the premises. No consideration is given to whether or not they are likely to be operating at maximum capacity at the same time.

The rating of each generator is deemed to be the A.C. (Alternating Current) rating of the generator. Ratings expressed in watts or kilowatts are based on the nominal voltage. For generation connected to our low voltage network the nominal voltage is 230V (between phase and neutral).

For example, a 3 phase generator with a rating of 50kW that is designed to be connected to our low voltage network, has a current rating of 50,000 ÷ (230 x 3) = 72.46A per phase*

Inverter Connected Generation

Some types of generation (e.g. PV Solar) produce D.C. (Direct Current) electricity.  Where this is the case they have to be connected to our network through inverters which convert the electricity to A.C. (Alternating Current) before it is connected to our network. The rating of this type of generation is deemed to be the inverter’s continuous steady state rating.

For example, a single phase PV solar installation that uses a 4kW inverter is deemed to have a rating of 4,000 ÷ 230 = 17.39A, which is just over the 16A per phase threshold*.

* Note, these examples assume the generation operates at a power factor of 1.0 (i.e. unity power factor).