There are several methods of classification of circuit breakers. On the basis of type of current they may be classified as ac circuit breakers and dc circuit breakers. AC circuit breakers may be classified on the basis of rated voltages. Circuit breakers below rated voltage of 1,000 V are known as the low-voltage circuit breakers and above 1,000 V are [...]
In this article we will discuss about operation and mounting of circuit breaker. Operation of Circuit Breaker: Each circuit breaker is provided with an operating mechanism. The functions of this mechanism are: (i) To close the breaker contacts rapidly without hesitation at all currents from zero to rated making current capacity (ii) To hold the breaker contacts together against the [...]
Relative merits and demerits of different types of conventional circuit breakers (bulk-oil circuit breakers, minimum oil circuit breakers and air-blast circuit breakers) are given below: 1. Bulk-Oil Circuit Breakers: Merits: Simplicity in construction, high rupturing capacity, suitability for automatic as well as manual operation; possibility of locating CTs in bushings. Demerits: Larger size and greater weight, fire hazard, explosion hazard, [...]
Here is a list of air-break circuit breakers: 1. Plain Break Type Air-Break Circuit Breaker 2. Magnetic Blow-Out Type Air-Break Circuit Breaker 3. Arc-Chute Air-Break Circuit Breaker. 1. Plain Break Type Air-Break Circuit Breaker: Plain break type air-break circuit breaker is the simplest one in which contacts is made in the shape of two horns. The air initially strikes across [...]
In this article we will discuss about:- 1. Meaning of Circuit Breakers 2. Operating Principle of Circuit Breakers 3. Arc Phenomena 4. Arc Extinction 5. Resistance Switching 6. Ratings. Meaning of Circuit Breakers: Circuit breakers are mechanical devices designed to close or open contact members, thus closing or opening of an electrical circuit under normal or abnormal conditions. Automatic circuit [...]
There are two methods of arc extinction in circuit breakers. They are: 1. High Resistance Method 2. Low Resistance or Current Zero Interruption. 1. High Resistance Method: In this case the arc is controlled in such a way that its effective resistance increases with the time so that the current is reduced to such a value that the heat produced [...]
The circuit breakers may be subjected to widely varying stresses under different operating conditions. The current may vary from a few amperes due to no-load magnetizing current of a transformer to the heaviest short-circuit currents amounting to a hundred kilo-amperes. The circuit impedance may also change within the first 10–4 to 10–3 second because open lines or cables connected to [...]
In this article we will discus about:- 1. Introduction to Re-Striking Voltage Transient 2. Expression for Re-Striking Voltage Transient 3. Classification 4. Characteristics 5. Factors Affecting. Introduction to Re-Striking Voltage Transient: Electrically a power system is an oscillatory network so that it is logical to expect that the interruption of fault current will give rise to a transient whose frequency [...]
Testing of circuit breaker is more difficult than the testing of other electrical equipment like transformer or machine because the short-circuit currents are very large. Also there is no satisfactory method of testing circuit breaker at reduced power. Classification of Tests: Testing of circuit breakers can be classified into two main groups, viz.: (I) Type tests and (II) Routine tests. [...]