Designing and Planning High Voltage Laboratories

1. Introduction

The demand of energy which has to be delivered over long distances is increasing in today's world due to industrial and economic development. Transportation of such a large amount of power needs extra high voltage transmission lines.

High voltage laboratories are an essential requirement for making acceptance tests for the equipment that go into operation in the extra high voltage transmission systems. In addition, they are also used in the development work on equipment for conducting research, and for planning to ensure economical and reliable extra high voltage transmission systems.

2. Transmission System Equipment in High Voltage Laboratories

A high voltage laboratory is expected to carry out withstand tests at high voltages on the following transmission system equipment:

(i) Transformers

(ii) Capacitors

(iii) Cables

(iv) Lightning arresters

(v) Isolators and circuit breakers

(vi) Line hardware and accessories

(vii) Other equipment like reactors, etc.

3. Activities and Studies in High Voltage Laboratories

On equipment, professors use high voltage laboratories for study and improvement work and conducting tests on equipment. At voltage, more dominant than the test voltage needed, this contains decision making of the security factor for dielectrics and trusty works under varied atmospheric conditions for example rain, fog… Occasionally, it is needed to work problems related test lines and another equipment under pollution and atmospheric conditions. It cannot be done enclosed spaces.

Research activities generally contain the following:

1) Breakdown case in insulating media for example solids, liquids, gases or composite systems

2) Insist on voltage on large gaps, requisites used in power systems and surface flashover works on equipment specific reference to the equipment.

3) Electrical interference works because of the discharges from equipment working at high voltages.

4) Works on insulation regulation on high voltage power systems.

5) High current case for example plasma physics, electric arcs.

Generally, high voltage laboratories equipped with an expensive tool and that increasing their build cost. As a result, planning and order have to be with caution done in order that with the test rig chosen, the enterprise isn't high and maximum beneficences of the laboratory is done.

4. Classification of High Voltage Laboratories

High voltage laboratories can be classified into three types, depending on the purpose for which they are goal and the available finances.

(i) Small laboratories

(ii) Medium laboratories

(iii) Large (general) laboratories

4.1 Small Laboratories

Small Laboratories

A small laboratory is one that contains d.c. or power frequency testequipment of less than 10 kW/10 WA rating and impulse equipment of energy rating of about lOKJor 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 1OO kV impulse voltage. Normally the equipment is meant for housing in a room or hall of size 15m x 10 m x 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. Such laboratories are meant for Engineering Colleges and Universities who decide to build such a facility with small resources for doing high voltage tests or research or for imparting training. In such a case, it is preferable that the Engineering college or University associate with a local industry or R & D organization. It is important to decide and define the responsibilities of the parties concerned as to how the test facilities and time can be shared. Another idea is to have the university to decide to own the laboratory fully but throw open the facilities of regular technical training and high voltage testing for the clients. Here it may be mentioned that many high voltage problems can be solved by tests at moderate voltage levels. Such laboratories can be built with an investment of 2 to 10 million rupees (at 1991 prices).