Classification of HV Laboratories (As per Size and Rating)
- A Small Size Laboratory
- Medium Size Laboratory
1. A Small Size Laboratory
- A small size laboratory is one that contains d.c. or power frequency test equipment of less than 10 kW / 10 WA rating and impulse equipment of energy rating of about 10 kJ or less.
- Voltage ratings can be about 300 kV for a.c., single unit or 500 to 600 kV a.c. for cascade units, 200 to 400 kV d.c. and less than 100 kV impulse voltage.
- Normally the equipment is meant for housing in a room or hall of size 15m x 10 mx 8 m.
- Sometimes the equipment ratings are limited such that they can be accommodated in a room of height 5 m to 6 m only.
2. Medium Size Laboratory
- Medium Size Laboratory High voltage laboratories may be either (a) indoor type or (b) outdoor type. The indoor type has the advantage of protection of testing equipment against variable weather conditions, simplicity in design and control of the test equipment, and provision of observation facilities during testing.
- But outdoor laboratories have the advantage of less cost due to the absence of building cost and the planned facility layout cost But outdoor test areas have limitations such as O absence of lifting and supporting facilities, (if) climatic conditions which may restrict or impede testing, (1/0 reproducibility of results not being guaranteed due to uncontrolled atmospheric conditions, and (iv) artificial and wet test studies which are difficult due to wind variation, etc.
- When high voltage laboratories are planned as indoor laboratories, the following figures fix the dimensions of the laboratories :
- Size of the test equipment for a.c., d.c., or impulse generators
- Distances or clearances between the test object and ground during test conditions and also between all the high voltage terminals and earthed or grounded surroundings such as walls, roofs of buildings, and other test equipment not energized.