- Circuit Breaker
- Purpose of Circuit Breaker
- Circuit Breaker with Internal Structure
- Operation of Circuit Breaker
- Switching Function
- Advantage over Fuse
- Basic Types of Circuit Breaker
- Circuit Breaker Contacts
- Arc Phenomenon
- How the Arc is Useful?
- Classification of Circuit Breaker
- Industrial Circuit Breakers
- What are the 3 types of breakers?
- Which circuit breaker is used in industry?
- List few Circuit Protection Device
- Explain most used electrical Circuit Breakers
- How Circuit breaker, Relays & Isolators differ from each other.
- How Industrial Circuit breaker differs from Residential Circuit Breaker?
A device that controls the electrical power system and serves to protect electrical equipment from damage.
Purpose of Circuit Breaker
A circuit breaker is described as a device that used to perform any one of the following functions:
- Under typical circumstances, makes or breaks a circuit manually or remotely.
- Breaks a circuit automatically in the event of a fault
- Creates a circuit manually or remotely when there is a malfunction.
Circuit Breaker with Internal Structure
Operation of Circuit Breaker
- The electromagnet is magnetized by electricity.
- The electromagnet is powerful enough to pull down a metal lever attached to the switch linkage when the current spikes to harmful levels.
- To break the circuit, the entire linkage moves, tilting the moving contact away from the stationary contact.
- Electricity stops flowing.
- For merging manual and automatic control for the switching function, a circuit breaker is employed.
- Relays are used to combine the circuit breaker’s automatic control.
- Only when there are fault situations is the automated control implemented.
Advantage over Fuse
- A fuse only functions once before needing to be replaced.
- The fundamental benefit of using a circuit breaker is that it may be reset (manually or automatically) to resume regular operation.
Basic Types of Circuit Breaker
Circuit Breaker Contacts there are two types of contacts:
- Primary contact
- Arcing contact
Circuit Breaker Contacts
- Copper (Cu), for example, is always used as the primary contact material.
- Arc resistance materials, such as tungsten or molybdenum, which have significantly lower conductivities than those used for primary contacts, are employed to create the arcing contact.
In typical operating circumstances, these contacts are kept closed and do not automatically open until and until the system develops a malfunction.
When a defect develops in any component of the system, the circuit breaker’s trip coils get energized and the movable contacts are forced apart by some sort of mechanism, which opens the circuit.
When a circuit break’s contacts separate due to a failure, an arc is created between them. As a result, the current can flow until the discharge stops.
Categories of Arcs
Circuit breakers’ arcs can be classified as
- High-pressure arcs
- Vacuum arcs.
How the Arc is Useful?
- In a way, the arc is advantageous since it offers the current after contact separation a low resistance path.
- It stops the system from experiencing abnormal switching overvoltages and related current hopping.
- The transition from the contacts’ current-carrying to current-breaking states is gradual but swift thanks to the arc.
- Arc depends on Degree of Ionization, Dimensions of the arc, Arc cross-section
Classification of Circuit Breaker
1.Based on Voltage
Based on voltage levels for which they are used, the circuit breakers are classified as:
2. Based on Location
Circuit breakers can be categorized as:
- Indoor type
- Outdoor type
3. Based on External Design
In terms of its actual structural design, outdoor circuit breakers can be identified into one of two categories:
- Dead tank type
- Live tank type
4.Based on Interrupting
The circuit breakers may be group into following categories:
- Oil Circuit Breakers
- Air Circuit Breakers
- Air-blast Circuit Breakers
- Sulphur Hexafluoride (SF6) CircuitBreakers
- Vacuum Circuit Breakers
Industrial Circuit Breakers
The Industrial Circuit Breakers are the one which shut off the electrical circuit when an overload condition occurs. They are classified into
- Industrial Circuit Breakers for High voltage
- Industrial Circuit Breakers for Medium voltage
- Industrial Circuit Breakers for Low voltage
- Industrial Electromagnetic circuit breakers
- Industrial Thermal Electromagnetic circuit breakers
- Industrial SF6 High Volt Circuit Breakers
Industrial Circuit Breakers for High voltage
- Industrial high-voltage circuit breakers are typically made at voltages of 72.5 kV or higher.
- Power transmission networks and circuits will contain these high voltage circuit breakers.
- Typically, they are the solenoid-operated circuit breakers with current-sensing protection relays that use current transformers for power.
- These high voltage circuit breakers at substations are crucial for shielding the connected buses and equipment from a variety of electrical problems, such as overloads and earth or ground faults.
- By the way they put out an arc, high voltage circuit breakers are generally categorized.
- Air blast, bulk oil, minimal oil, a vacuum, and the SF6 (sulphur hexafluoride) gas are some of the techniques used to put out the arc.
- Due to environmental concerns and the expense of oil spills that can occur with oil-type circuit breakers, the majority of more recent industrial circuit breakers now use SF6 gas to extinguish the arc.
Industrial Circuit Breakers for Medium Voltage
- Circuit breakers for medium voltages can handle voltages of 1 to 72 kV.
- Several of these switches can be mounted either individually outdoors or in switchgear-like lineups inside metal enclosures for indoor use.
- Similar to high-voltage industrial circuit breakers, medium-voltage circuit breakers are categorized based on how they put out an arc, such as with an SF6 circuit breaker, an air circuit breaker, or a vacuum circuit switch breaker.
Industrial Circuit Breakers for Low Voltage
- Low volt circuit breakers are frequently made for voltages rated at less than 1 kV.
- They are widely used in both industrial facilities and household and commercial settings.
- Low voltage circuit breakers include
- Miniature circuit breakers with current ratings under 100 AT
- Molded case circuit breakers with ratings no higher than 2,500A.
Electromagnetic circuit breakers for Industry
- A magnetic circuit breaker uses an electromagnetic solenoid with a current-dependent magnetic power design.
- The solenoid’s pull grows strong enough to release a latch that seals the contacts as the current flowing through the breaker rises over the preset threshold, which is effectively the breaker’s rating, and that circuit is severed.
Circuit breakers with an Industrial Thermal Electromagnetic Design
- Thermal electromagnetic circuit breakers use both bimetallic strip trip and electromagnetic circuit-breaking techniques.
- Whereas the bimetallic strip reacts to less severe but persistent over-current circumstances, the electromagnet reacts promptly to massive current surges or short circuits.
- The thermal component of the thermal magnetic industrial circuit breakers provides an inverse time response, allowing lesser overloads to endure for a while but tripping considerably more quickly for the bigger overcurrents.
- The magnetic potion immediately breaks the circuit in the event of an extremely strong surge.
SF6 High Voltage Industrial Circuit Breakers
- The gas sulphur hexafluoride surrounds the contacts in SF6 industrial circuit breakers, quenching the arc that results.
- In transmission level where heavy currents are present, industrial SF6 high voltage circuit breakers are typically used.
- Due to its extremely high dielectric strength, which acts as an insulating medium, this gas is known to quickly extinguish the arc.
- The high current created as a result is instantly reduced or eliminated.
- High electro-negativity and superior insulation are two characteristics of the SF6 circuit breaker. It operates from 33KV to 800KV in voltage.
What are the 3 types of breakers?
- GFCI ( Ground Fault Circuit Interrupters)
- AFCI (Arc Fault Circuit Interrupters).
Which circuit breaker is used in industry?
SF6 Industrial Circuit Breakers are very popular for extinguishing high voltage arcs in industrial settings. It is used due to their reliability in normal industrial conditions.
List few Circuit Protection Device
- Circuit Breaker
- Electrical Fuse
- Transient Voltage Suppression Diode
- Residual Current Device
Explain most used electrical Circuit Breakers
MCB (Miniature Circuit Breaker)
- Low-voltage circuit breakers come in the form of MCBs (Miniature Circuit Breakers).
- For minimal power requirements, such as home uses or tiny electrical panels, MCB is utilized.
- Only 100 A can be used with an MCB and interrupt rating of an MCB is up to 18000 A.
MCCB (Molded Case Circuit Breaker)
- Low-voltage circuit breakers include MCCBs (Molded Case Circuit Breakers).
- MCCBs are utilized in high power applications like industrial or significant commercial ones.
- It is usable up to 2500 A. It is now practical for usage in larger applications.
- The MCCB features a number of tripping options, including ground fault pickup, immediate pickup, continuous ampere, long time delay, short time pick up, and short time pick up.
- These trip functions can be adjusted, giving the user more freedom when building a circuit because the trip parameters can be altered in accordance with their needs.
RCCB (Residual Current Circuit Breaker)
- Low-voltage circuit breakers include RCCBs (Residual Current Circuit Breakers).
- To guard against earth leakage fault currents, RCCBs are utilised.
- RCCBs normally only have current ratings of up to 160A.
- RCCB offers safety from electric shocks.
- This is so that the RCCB may trip the circuit when it detects an earth leakage, which is basically its function.
RCBO (Residual Current Circuit Breaker with Over current)
- Low-voltage circuit breakers include RCBOs (Residual Current Circuit Breaker with Overcurrent).
- A RCBO is used to defend against overcurrent and earth leakage fault current.
- Overload and over-current are other risks that the RCBO protects against.
- Fundamentally, it is a hybrid of MCCB and RCCB and heavily utilizes microcontrollers.
- For this reason, it is more beneficial than RRCB because RCCB does not offer over-current protection.
- Moreover, some RCBOs feature indicators to display when an earth fault trip occurs.
- This feature is particularly beneficial because it speeds up the engineer’s ability to diagnose problems.
MPCB (Motor Protection Circuit Breaker)
- Low-voltage circuit breakers include MPCBs (Motor Protection Circuit Breakers).
- The MPCB performs the same task as the MCCB, but it has electrical properties that were specifically intended to effectively safeguard the motors from various fault types.
- Moreover, it contains an on/off switch for powering on or off the motor’s power supply.
- It should be noted that although an MCCB can also be used to protect motors, it does so with fewer capabilities than an MPCB.
- Phase loss, current unbalance, and under-voltage faults are some other issues from which an MPCB can shield the motor.
- Auto-resetting is a unique function of the MPCB.
- When the motor trips, it enables the motor to resume running after a predetermined amount of time.
- A movable bimetallic strip on the MPCB protects against overload. For overload protection, the strip can be changed between any two predetermined values.
- Line-to-ground and line-to-line fault protection is another feature of MPCB.
VCB (Vacuum Circuit Breaker)
- One kind of medium voltage circuit breaker is the vacuum circuit breaker.
- The main purpose of circuit breakers is to put out the arc created during high-tripping currents or power outages.
- Hence, it is referred to as a vacuum circuit breaker when the vacuum is employed to put out the arc. 11KV to 33KV voltages are used with VCB.
- A significant amount of arc is produced when the fixed and moving contacts drift apart from one another during the trip or off situations.
- With this circuit breaker, arc formation causes the vacuum’s dielectric strength to grow because the arc is taking place inside of a vacuum enclosure.
- The high current created as a result is instantly reduced or eliminated.
- It has outstanding interruption and dielectric recovery characteristics.
Oil Circuit Breaker
- One kind of high-voltage circuit breaker is an oil circuit breaker.
- Oil circuit breakers are used to put out arcs when oil is employed to do so.
- Oil is utilized in this sort of circuit breaker, but mineral oil is preferred.
- The fixed and movable contacts are submerged in the insulating fluid.
- The oil is evaporated and breaks down into hydrogen gas when the arc is created. At the end, a hydrogen bubble forms around the arc.
- After the current reaches the cycle’s zero crossings, the highly compressed gas bubble that forms around the arc prevents the arc from being struck again.
How Circuit breaker, Relays & Isolators differ from each other.
How Industrial Circuit breaker differs from Residential Circuit Breaker?
- Industrial circuit breakers interrupt electrical circuits upon overloading. Protects the electrical circuit from damage and fire. To prevent electrical fires, they must find electrical faults.
- Residential Breakers prevent residential electrical failures. It replaces fuse-protected wiring. The fuse melts when too much current goes through it. Fuses are cheaper but must be replaced after each electrical disruption. Circuit breakers restart power.