Everything You Need to Know About Circuit Breakers: Introduction, Applications, and Types

 

Table of Content

1. What is CIRCUIT BREAKER
2. NEED OF CIRCUIT BREAKER
3. TYPES OF CIRCUIT BREAKERS
4. CIRCUIT BREAKERS AT A GLANCE
5. MEDIUM VOLTAGE & HIGH VOLTAGE CIRCUIT BREAKERS

 

What is CIRCUIT BREAKER

The circuit breaker is a switching device which also offers protection by tripping & cutting off the supply to load in case of fault. Primarily the circuit breakers are used for switching of different kinds of load in Industries, Buildings, Commercial Complexes, and Hotels, etc.

NEED OF CIRCUIT BREAKER

Many kind of abnormal conditions are there which exist in our electrical system that have the potential to damage the circuit & its components. These conditions are defined as ‘FAULTS’.Further, fault is categorized as mentioned below:

• Overload
• Short Circuit
• Earth

In order to keep our electrical components & system safe, it is mandatory to protect our system against the above faults. This leads to the need of circuit breaker.

 

TYPES OF CIRCUIT BREAKERS

Circuit breakers mainly are categorized on the basis of application as per voltage:

1) Low Voltage Circuit Breaker

• MCCB
• ACB
• MCB
• RCCB

2)  Medium Voltage Circuit Breakers

3) SF6/VACUUM Circuit Breakers

4) High Voltage Circuit Breakers

• VCB
• SF6
• OCB
• ABCB

 

CIRCUIT BREAKERS AT A GLANCE:

LOW VOLTAGE CIRCUIT BREAKERS

Circuit Breakers operating for the voltage up to 1KV are LV or Low Voltage Circuit Breakers which are as follows:

• MOLDED CASE CIRCUIT BREAKER (MCCB)

MCCB or Molded Case Circuit Breaker is a kind of circuit breaker which is enclosed in the moulding or housing of a moulded material & that is the reason it is known as Molded Case Circuit Breaker. It is generally used for the current ratings upto 1600A & fault level upto 150KA. It offers protection against overload & short circuits through bimetal & solenoid, these days Microprocessor based MCCBs are being very popular due to the quick functioning of their electronic type release.

• MINIATURE CIRCUIT BREAKER (MCB)

MCB or Miniature Circuit Breaker is a circuit breaker which is used for protection where current ratings are lower. It can be used upto 125A circuits & like MCCBs it also offers protection against overload & short circuit through bimetal & solenoid. These days Class 3 MCBs are very popular due to their ability of tripping quickly & also minimum loss of let through energy.

•  AIR CIRCUIT BREAKER (ACB)

AIR CIRCUIT BREAKER or ACB as the name suggests it’s the circuit breaker where the medium of arc quenching is air. ACB is used for the high current applications, or we can say that ACB can offer protection against overload & short circuit upto 6300A. Tripping in ACB is achieved through release. The release is known as the mind of ACB as it only suggests the ACB to trip in case of fault.

• MOTOR PROTECTION CIRCUIT BREAKER (MPCB)

MPCBs are used specially for motor protections. MPCB as a standalone device offers protection against Overload, Short Circuit & Single Phasing, thus is used specifically for motor applications.

• RESIDUAL CURRENT CIRCUIT BREAKER (RCCB)

RCCBs as the name suggests offer protection against Earth Leakage. It is used in homes, offices & industries according to the current sensitivity required as per application. In case of current leakage it senses the same & trips thus, saving the human & circuit from shock & adverse effects of current leakage.

 

MEDIUM VOLTAGE & HIGH VOLTAGE CIRCUIT BREAKERS

Voltage level from 1KV-69KV is categorized under medium & 69KV-230KV is categorized as High Voltage. Circuit Breakers operating in these voltage ranges are known as Medium & High Voltage CBs respectively.

• VACUUM CIRCUIT BREAKER  (VCB)

Vacuum Circuit Breaker or VCB is used for Medium Voltage applications. In VCB the contacts operation & arc quenching takes place inside bottles where Vacuum is present.

• SF6 CIRCUIT BREAKER

SF6 circuit breakers are also used mainly in medium voltage applications. In this breaker SF6 gas is used for arc quenching due to its ability of quenching the arc very efficiently. SF6 Breakers being highly efficient in arc quenching are still not preferred much as SF6 being a poisonous gas, is dangerous to environment & humans.

• OIL CIRCUIT BREAKER (OCB)

Oil Circuit Breakers were also used on high voltages & Oil was used as the arc quenching medium.