WHAT ARE CIRCUIT BREAKERS?TYPE OF CIRCUIT BREAKERS?

CIRCUIT BREAKER:

Today we will learn about what are circuit breakers? Type of circuit breaker and their operation and principle their uses.

INTRODUCTION OF CIRCUIT BREAKER

We learn about circuit breaker and their types. A most commonly major part of the electrical. So this article describe useful to understand easily and simply for students and others.

In all electrical circuits are used circuit breakers. It is a protection device that protects the electrical circuit. it protects the distribution line, Transformer, Small and medium size of motors, lighting circuit, generating substation,s and power plants. The commercial circuit breakers are build up 600A, 500A, and 100A.

 WHAT ARE CIRCUIT  BREAKERS?

A circuit breaker is a mechanical device that is performed as open and close contact. When current will be high or fault condition. it means the electrical circuit is in abnormal condition then the circuit breaker opens and cut-out the circuit. Now the circuit is in the normal condition we restored them with close contact. A Circuit breaker is an also a switching device which operates on normal and abnormal condition of current. Its switching function protect the circuit and protect to damage to another device. Design of circuit breaker automatic trip in abnormal condition or over current. Circuit breaker follows some duties 

1. It carries a full load current without overheating and damage.

2. It opens in abnormal conditions just like overcurrent or fault.

3. A load in normal condition circuit breaker will be close.

4. Circuit breaker only trips depending upon their design or their selectivity range.

 

The circuit breaker cuts out the current according to its specified range. If we take a circuit breaker that exceeds the current capacity, it does not prevent overcurrent and destroys the entire circuit, so we have to select the circuit sitting The circuit breaker of the correct range should be used according to the prescribed current. When a fault occurs in a circuit, the circuit breaker changes it and separates the circuit from the fault, and prevents it from getting damaged.

The circuit breakers are rated in terms of maximum voltage number of poles frequency maximum continuous current-carrying capacity e maximum interrupted. Circuit breakers are also rated in MVA which is the product of interrupted current rated voltage.

OPERATION AND PRINCIPLES

A circuit breaker is consists of fixed and moving contact when a normal condition both are touching each other and current flow continuously. whenever a fault occurs then the tripping coil energized and moving contacts pressurized to pull open the contacts and protect to damage is called abnormal condition in this condition circuit broken from the main circuit.

CIRCUIT BREAKER

Properties of circuit breakers

1. High dielectric strength

2. Noninflammability

3. High thermal stability

4. Commercially available at moderate cost

Arc extinction of circuit breaker-

There are two methods of arc Extinction 

1.High Resistance Method-

In this method increasing the value of resistance with time.This method is employed in DC circuit breaker and low to medium power.Resistance can be increase by

A) Reducing the concentration of the ionized particles.

B) Increase arc length 

C)  Splitting the arc

D) Reducing the arc x- section area

2.Low Resistance or Zero Point Method-

In this method decreasing the value of resistance and current is zero. This method is employed in AC circuit breaker and moderates to high power.Resistance can be Decrease by

A) High pressure 

B) Cooling

C) Blast effect 

Arc, Restriking, and recovery voltages-

The voltage across the contacts during the arcing period is known as Arc voltage.

Rate of Rise of Restriking Voltage (RRRV)-

RRRV is obtained by drawing a straight line through zero and tangential.

Current Chopping -

In circuit breaker when low inductive current, the current falls to zero then natural current become zero.

Arc, Restriking, and recovery voltages

TYPE OF CIRCUIT BREAKERS

The most commonly used circuit breaker follows 

1.Oil circuit breakers 

2.Low voltage air circuit breakers 

3.Air blast circuit breaker 

4.Vacuum circuit breakers 

5.Sulphur hexafluoride sf6 circuit breaker

 Rating of circuit breaker-

The circuit breaker is formed mainly three types of rating 

1.Breaking capacity  

2. making capacity

3. short time duty

Breaking capacity- 

It is generally expressed in terms of MVA ad is equal to the product of rated breaking current in amperes rated voltage in KV and factor which depend upon a number of phases.

Breaking capacity=Phase(single-phase or three-phase) VIx1/1000000

Making capacity-

 It is a maximum possibility of the read circuit breaker is closed under short circuit conditions the making capacity of the circuit breaker depends upon the effect of electromagnetic force which is proportional to the square of the peak value of making current.

Making a capacity = 2.55 x symmetrical breaking capacity

Short time rating- 

Short time rated current is the current that can safely be applied with the circuit breaker in its normal condition

Normal current rating -

The rated normal current of the circuit breaker is an RMS value of the current.

USES 

1.Circuit breakers are used in high voltages line, low voltage line, transformer.

2. Protect the electrical circuit.

3. Protect all types of electrical equipment using in the circuit.

This topic is related to the introduction of circuit breakers which is the most common part of an electrical and electrical circuit, We learn and discuss this topic easily and deeply knowledge about circuit breakers their types, and operation their principle of the circuit breaker.

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