Protective Equipment

Most distribution transformers are protected by lightning arresters, fuses and thermal overload breakers that are either contained in the transformer or must be mounted external to the transformer.

Lightning Arresters and Fuses Picture Lightning arresters are designed to protect the transformer from very high lightning surge voltages, as well as to prevent the surge from damaging other protective equipment.

Fuses offer short circuit protection from internal faults or short circuits by removing the damaged transformer from the primary line. If not removed from the line, a damaged transformer may cause many more customers to suffer a power outage unnecessarily.

Thermal overload protection for the transformer is designed to trip in the event of a short circuit on the secondary side, or in the event of "thermal overload" due to sustained high currents.