Low Voltage Circuit Breaker

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Low Voltage Circuit Breaker Present by Mohammad Faizan Abdul Haseeb Muhammad Aamir Zia Maqsood ur Rehman Tahal Das Instructor Dr. Abdul Rehman Abbasi GSESIT – Hamdard University Advance Power Distribution

Transcript of Low Voltage Circuit Breaker

Page 1: Low Voltage Circuit Breaker

Low Voltage Circuit Breaker

Present byMohammad Faizan

Abdul HaseebMuhammad Aamir ZiaMaqsood ur Rehman

Tahal Das

InstructorDr. Abdul Rehman Abbasi

GSESIT – Hamdard University

Advance Power Distribution

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Circuit Breakers

Device designed to open the circuit automatically under abnormal conditions without damage to itself when properly applied within its rating.

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Basic Difference Between Fuse & Circuit Breaker

Fuse• Design to open the

circuit when current exceed the desire limit.

• If fuse is blow then it has to be replace.

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Circuit Breaker• Not directly design to open the

circuit like Fuse or Breaker• Its opening depend upon magnitude

and time of Overload current • Circuit breaker can be reset (either

manually or automatically) to resume normal operation.

Basic Difference Between Fuse & Circuit Breaker

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Self-Actuated Circuit BreakerTwo methods circuit breakers sense circuit current:

Thermal• Sense circuit current through

the production of heat• Generally uses some type of

heating element in series with the load

• The heater is located close to a bimetallic strip

• The bimetallic strip is mechanically connected to the moveable contacts

• There is a time delay before the circuit opens

• The time delay depends on the amount of over current

Magnetic• It also known as Instantaneous trip

circuit breaker• Senses circuit current by connecting a

coil in series with the load• When current flows thought the

circuit, a magnetic field is established around the coil

• The magnetic field attracts the metal arm of a solenoid

• When the magnetic field becomes intense enough the metal arm mechanically opens the contacts

• There is very little time delay in opening the contacts when an abnormal condition occurs

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Thermal Circuit Breaker

Symbol Schematic Diagram

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Overheated Circuit Breaker (Thermal Type)

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Thermal Breaker

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Magnetic circuit breaker

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Magnetic Circuit Breaker

Symbol Schematic Diagram

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Thermo-magnetic circuit breaker

• Employs both thermal and magnetic current sensors

• More efficient and disconnect within millisecond

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Miniature Circuit Breaker (MCB)• Normally work with currents below 100 amperes.• They are the type of low voltage circuit breaker that is

typically found in the fuse box of a residential or commercial building.

• Miniature circuit breakers are designed to be installed in a shared fuse box, from which several electric circuits are protected.

• The current ratings of a miniature circuit breaker normally have fixed values that are established during production and can’t me modified by the user

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Miniature Circuit Breaker (MCB)

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Single Poles MCB A Single-Pole low voltage circuit breaker only occupies one

space in a fuse box. Single-pole circuit breakers are typically used for electric circuits with low power requirements that only use one live conductor, such as those providing power for lamps or general purpose electric outlets.

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Double-pole MCB A Double-Pole low voltage circuit breaker occupies two

spaces in a fuse box, and is used for devices that operate with two live conductors, such as most residential Air Conditioner models. When a double-pole circuit breaker is tripped, both lines are disconnected even if only one of them was involved in the electrical fault.

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Triple-pole MCB

A Triple-Pole low voltage circuit breaker occupies three spaces in a fuse box and is used to protect electric equipment that works with three-phase power. The electric motors of elevators and large central Air Conditioning units typically work with three-phase power and are protected with triple-pole low voltage circuit breakers.

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• Higher current ratings when compared to miniature circuit breakers.

• But due to their size they can’t be installed in a traditional fuse box. Instead.

• Molded case circuit breakers are typically installed in individual metallic boxes or in industrial switchboards which have larger slots to accommodate them.

• Some fuse boxes that are designed for miniature circuit breakers may include one slot for a molded case circuit breaker that is used as the main breaker

Molded Case Circuit Breaker (MCCB)

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Overheated Circuit breaker Application

• Overload Heater• Its basically used to

protect motor from overheating

• Its Thermal model of heating and cooling is match with model of Model

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Earth Leakage Circuit Breaker (ELCB)An earth leakage circuit breaker (ELCB) is a safety device used in electrical installations with high earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected. Once widely used, more recent installations instead use residual current circuit breakers which instead detect leakage current directly.

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Earth Leakage Circuit Breaker (ELCB)

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Residual Current Circuit Breaker (RCCB)

• Its trip when sense earth fault current

• Check the phase (line) current and neutral (return) current

• Trip if fault remain up to 30mSec• Its extremely effective in shock

protection• 30mA and 100mA tripping are

widely use

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Difference between ELCB and RCCB

ELCB• It is old technology• It is connected to

Phase, Neutral as well as earth line

• It is not recommended over RCCB

RCCB• Its New technology•It is connected to only Phase and Neutral line•It is also known as Current-operated ELCB

Their working principle is same but their operation and connectivity and different

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Thank you