CSP technology is more known for high performance distribution transformers which mitigate the operation and maintenance problem associated with conventional transformers. CSP technology enables transformers to protect itself from secondary faults, lightning protection, persistent serve overloads, and provides visual warming of the overload conditions. CSP technology also protects the distribution system to which it is connected, in case of its failure. This means, that in case of failure of the transformers, it gets isolated from the system.

CSP System has four essential Components. They are:

Oil immersed Circuit Breaker for Overload and secondary fault protection

Signal Light for indication during overload conditions on transformers

HV Fuse for over-current , protection by isolating a failed transformer from transformers from the system

Surge Arrestor for lightning protection.

The Oil immersed circuit breaker is installed on the secondary (low voltage) side of the transformers. It provides the entire over current protection to the transformers and responds to secondary faults external to the transformers by tripping and prevents any thermal damage occurring to the transformers.

Besides protecting from secondary fault, the breaker also provides thermal protection to the transformer. It is an electro mechanical device with three major elements. These elements are:

1.Temperature sensing through the use of bimetallic strips which are built into the breaker such that the load current flows through them. The bimetallic strips respond thermally to the temperature oil and also to the temperature changes created by the flow of the load current through them.

Latching and tripping functions

The signal light latch

The emergency control assembly.

The magnetic trip device

It works as current interrupter

The signal circuit is mechanically connected to the circuit breaker latching and bimetal systems through an auxiliary contact. A signal light is mounted on the wall of the transformer tank. It gives a visual external indication when the transformers oil temperature reaches a specified preset value of temperature during overload condition. Once the signal light glows then it can be turned off only by manually operating the external handle of the circuit breaker.

In CSP transformers, the primary fuse is placed in oil and connected in series with the primary winding. The expulsion fuse is to protect that part of the electrical distribution system, which is ahead of the transformers from faults which occur inside of the distribution transformers. If a fault occurs in the windings or some other part of the transformer, it will cause abnormally large currents to flow, resulting in the fuse to melt open and clear the circuit . Thus, the fault is limited only to those customers who are served by this particular transformers and service is maintained on the rest of the system.

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