0.4 kV Switchgear

 

The low voltage auxiliary and general power supply switchgear consists of main distribution panels and sub-distribution panels. The main auxiliary and general supply distribution panels, as well as the main lightening supply distribution panel, placed in the space between bunkers, are supplied by corresponding 6.3 kV switchgears though dry-type transformers 6.3/0.4 kV.

The auxiliary power supply has two main distribution panels. Each of them is supplied from a separate transformer 1000 kVA connected to separate sections of the 6.3 kV switchgear. They supply power consumers either directly or through sub distribution panels. The main general supply distribution panel is supplied by the switchgear 6.3 kV with the help of a transformer 1000 kVA, while the main lightening supply distribution panel is supplied by the transformer 630 kVA. Auxiliary and general power supply distribution panels, in the case of a main supply failure, can be automatically switched over to supply from the stand-by transformer 1000 kVA. Consumers on the coal depot and beside the electrostatic precipitator also have separate transformers and power distribution. The coal transport system and the flue gas desulphurizing plant have their own switchgear 6.3/0.4 kV for supply of high voltage and low voltage consumers. Sub-distribution panels are used for supply of consumers grouped by certain technological equipment. They are supplied by the main distribution panels.

The 220 kV switchyard has its own sub-distribution cubicles connected to the general and the emergency power supply placed in a common relay house within the switchyard. Distribution and sub-distribution panels are made as switching units with fixed and withdrawable apparatus

groups, depending on their purpose.

Diesel generating set and emergency power supply

For the purpose of supply of essential consumers in the case of a failure of electric energy supply, a diesel generating unit 800 kVA is installed to take over the supply within a period of a few seconds.

The diesel – generating set supplies the main distribution panel for emergency consumption from which power is distributed to essential consumers.

Checking reliability of operation is performed by means of a testing system of the operation of the diesel generating set in parallel to the grid.

ELECTRIC MOTOR DRIVES

For the drives of feeding pumps, sea cooling water pumps, condensing pumps, absorber pumps, coal mills and ventilators for fresh air, flue gas, hot air for mills and recirculation of flue gas, high voltage electric motors are built in with a power range from 160 to 4100 kW, while smaller drives are equipped with low voltage motors within a wide range of powers.

Thermal Power Plant Plomin 2