11kV, 33kV. It is generated by 3phase alternators in parrarell. The electrical energy produced at the power station is Alternating Current (AC). AC is preferred for transmission because it can be stepped up and down and with ease and efficiency. With AC, the maintenance of substations is easier and cheaper as compared to DC. With the help of a step-up transformer, electric current is stepped up to 132kV, 220kV and 400kV. Power is stepped up for transmission so as to reduce losses during transmission and saving conductor material. High voltage transmission lines are used to transmit this heavy current from the generating station to transmission substation.
PRIMARY DISTRIBUTION SUBSTATION
The high voltage line terminates at a distribution substation. The substation receives voltage at 400kV, 220kV, 132kV or 66kV with the help of large 3phase step-down transformers. The substation is capable of transmitting 6.6kV,11kV, 33kV and 66kV through different feeders depending on the target load. The common 11kV line runs along important roads of the city. Large consumers being fed by 33 and 11kV have their own substations for stepping down this voltage.
SECONDARY DISTRIBUTION SUBSTATION
11kV or 33kV and step it down to 415/240V (Kenya). As opposed to primary distribution substations, the secondary ones do not have complicated equipment since they handle a smaller amount of current. They are located near neighborhoods and are likely to be encountered by the customers.
240V while 3phase shall be supplied to large industrial consumers at 415V. At the consumer intake, the power supply company provides the Energy meter depending on the tariff
CONSUMER CONTROL UNIT
The CCU is the point where the power is distributed throughout the consumer’s premises via fuses, conductors and circuit breakers. This however is not supplied by the power distribution company. Current in the premises is controlled at this point which has a single gang isolator switch to isolate the entire premise.