ECI Electrical Bushings

ECI  bushings are essential components for a wide range of electrical equipment such as power transformers, shunt reactors, circuit breakers, and capacitors. These seemingly simple devices perform the critical function of carrying current at high voltage through equipment enclosures. They perform this function by providing an insulating barrier between the live conductor and the metallic (conducting) body of the electrical apparatus (which is at ground potential).

Simply we can say the purpose of an electrical bushing is to transmit electrical power in or out of enclosures, i.e., barriers, of an electrical apparatus such as transformers, circuit breakers, shunt reactors, and power capacitors.

Terminal blocks are used to transmit electrical energy through conductive materials; there is a large number of styles and number of contacts available.

Applications and Limitations of Solid Type Bushings

Solid bushings are commonly used in applications ranging from small distribution transformers and circuit switchers to large generator step-up transformers and hydrogen-cooled power generators.

The primary limitation of the solid bushing is its ability to withstand 60-Hz voltages above 90 kV. Hence, its applications are limited to 25-kV equipment ratings, which have test voltages of 70 kV.

Recent applications require low partial-discharge limits on the 25-kV terminals during transformer test and have caused further restrictions on the use of this type of bushing.

In these cases, either a specially designed solid bushing, with unique grading shielding that enables low inherent partial-discharge levels, or a more expensive capacitance-graded bushing must be used.