1.3 TRANSFORMER PROTECTION BEST PRACTICES

Transformer failures and safety hazards can be avoided or minimized by ensuring that the conductors and equipment are properly sized, protected and adequately grounded. Incorrect installation of transformers can result in fires from improper protection, as well as electric shock from inadequate grounding.

a)    Once the transformer is placed, the tank must be permanently grounded with a correctly sized and properly installed permanent ground.

b)    Access should be restricted to the transformer liquid-filled compartment in conditions of excessive humidity or rain.

c)    Dry air should be continuously pumped into the gas space if humidity exceeds 70%.

d)    Transformer should be given protection against rain such that no water gets inside.

e)    All equipment used in the handling of the fluid (hoses, pumps, etc.) should be clean and dry. If the insulating liquid for inspection is drawn out, its level should not go below the top of windings.

f)     Sufficient gas pressure must be maintained to allow a positive pressure of 1 psi to 2 psi at all times (even at low amb.temp.) when liquid-filled transformers are stored outside.

g)    Final inspection of the transformer is essential before it is energized. All electrical connections, bushings, draw lead connections should be checked.

h)    Upon loading the transformer it should be kept under observation during the first few hours of operation. All temperatures and pressures should be checked in the transformer tank during the first week of operation.

i)      Surge arresters must be installed and connected to the transformer bushing / terminals with the shortest possible leads to protect the equipment from line switching surges and lightning.