What is Circuit Breaker?
A circuit breaker is a device that may manually or automatically break a circuit under all circumstances, including no load, full load, and short circuit.
A circuit breaker is a device that can perform any of the following functions:
- Under typical circumstances, manually or by remote control, makes or breaks a circuit.
- When a circuit is tripped, it automatically breaks the circuit.
- Under fault conditions, makes the circuit trip either manually or remotely.
- A circuit breaker is utilized to incorporate both manual and automatic switching control.
- Relays are used to control the circuit breaker automatically.
- Only in the event of a fault, automated control used.
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Types of Circuit Breaker:
Circuit Breaker classified as two types, they are:
- AC Circuit Breaker,
- DC Circuit Breaker.
AC Circuit Breaker:
Based on different categories AC circuit breaker have different types:
1.Based on Voltage:
- Low Voltage Circuit Breaker,
- Medium Voltage Circuit Breaker,
- High Voltage Circuit Breaker,
- Ultra-High Voltage Circuit Breaker.
2.Based on Location:
- Indoor Circuit Breaker,
- Outdoor Circuit Breaker.
3.Based on External Design:
- Dead Tank Circuit Breaker,
- Live Tank Circuit Breaker.
4.Based on Interrupting Media:
- Air Blast Circuit Breaker,
- Oil Circuit Breaker,
- Air Circuit Breaker,
- Vacuum Circuit Breaker,
- SF6 Circuit Breaker.
DC Circuit Breaker:
Similarly, as AC circuit breaker, DC circuit breaker has a type called HVDC (High Voltage Direct Current) Circuit Breaker.
AC Circuit Breaker Types:
1.Based on Voltage:
Low Voltage Circuit Breaker:
Low voltage circuit breakers are mostly employed in small-scale enterprises and are rated for low voltages up to 1 kV. Low voltage circuit breaker can be mounted in the multi-tiers in low voltage switch boards and switchgear cabinets.
Medium Voltage Circuit Breaker:
A medium voltage circuit breaker works with a voltage range of 10 to 35 kV. Low voltage is insufficient for them to function effectively. The voltage would be extremely high in the case of an HT circuit breaker, hence it would not work under these circumstances. As a result, operating on medium voltage breaker types is the best alternative. In contrast to other types of breakers, medium voltage circuit breakers can also be operated manually. Medium voltage circuit breakers, on the other hand, can be controlled electrically. This can happen when using a solenoid or another type of energy storage device.
- Medium voltage breakers are ecologically friendly, operate safely, have automatic alignment, are simple to operate and manage them.
- They are quick to install.
- They are also reliable, safe, and economical.
High Voltage Circuit Breaker:
Electrical power transmission network line are controlled and protected by the high voltage circuit breaker. For voltage higher than the 72.5KV high voltage circuit breaker are used in substation with the support of the protective relays and control panel. The breakers are completely solenoid operated one. The total protective equipment, relays, busbar connection through overload and ground fault are completely earthing. The current value is measured through current transformer (CT).
Ultra High Voltage Circuit Breaker:
Ultra High Voltage Circuit Breaker systems breaker operation speed is critical since a lack of stability would be detrimental to the system. It is possible to interrupt for a total of two cycles, or 40 milliseconds. The fundamental contribution of the ultra high voltage circuit breaker is high operating pressure available for fast mechanism operation and guaranteed arc extinction in half a cycle of arcing.
2.Based on Location:
Indoor Circuit Breaker:
Indoor circuit breakers are intended for use indoors or in weather-resistant enclosures.
They’re usually operated at a medium voltage.
They are enclosed in a metal switchgear casing.
Indoor Circuit Breaker can be applied to maximum voltage of 33KV.
Outdoor Circuit Breaker:
Because of their design and location, outdoor circuit breakers can be used outside without a roof. In comparison to the interior breakers, their external enclosure layout is more durable and can tolerate external impact.
3.Based on External Design:
Dead Tank Circuit Breaker:
Dead tank circuit breakers are breakers with an enclosed tank that is at ground voltage. All of the insulating and interrupting medium is contained within their tank. To put it another way, the tank is either shorted to the ground or at dead potential. The switching unit is housed in a metal container that has an earth potential. Because the incoming/outgoing wires pass through insulated bushings, current transformers can be installed on them but in live tank circuit breaker separate CT to be installed.
Live Tank Circuit Breaker:
Live tank circuit breakers consist of tank housing interrupter that is at a potential above the ground. It is elevated from the ground, with a layer of insulation in between them.The switching unit of the circuit breaker is housed in an insulator bushing that is live at line voltage (or some voltage above ground). Live tank circuit breakers are less expensive and take up less space than dead tank circuit breakers.
4.Based on Interrupting Media:
Other than the above different types of circuit breakers, based on their properties, interruption and application of uses, breakers are explained in detail as:
Air Blast Circuit Breaker:
In air blast circuit breaker, as an arc cooling medium, a high-pressure air blast is used. The contacts are opened in response to the opening of the blast valve, which creates an air-blast flow. The arc is cooled by the air blast, which also sweeps the arcing products into the atmosphere. This causes the dielectric strength of the medium between the contacts to rapidly grow, preventing the arc from being re-established.The arc is finally extinguished, interrupting the current flow.
Advantages of Air Blast Circuit Breaker:
- The risk of fire is no longer a concern.
- The blast entirely removes the arcing products, eliminating the need for oil change.
- These breakers have been shrunk in size.
- The arcing time is relatively short due to the quick increase in dielectric strength. It reduces the amount of oil that is burned.
- The arc energy in oil circuit breakers is also a small fraction.
- High-pressure air aids arc extinction, which is independent of the fault current to be interrupted.
Disadvantages of Air Blast Circuit Breaker:
- These circuit breakers are extremely sensitive to changes in the pace at which the restriking voltage rises.
- The compressor plant, which requires regular maintenance, provides the air-blast.
Application of Air Blast Circuit Breaker:
Air blast circuit breakers were employed for open terminal HV applications with voltages ranging from 400 kV to 765 kV, particularly where faster breaker operation was necessary.
Oil Circuit Breaker:
Oil circuit breakers that use insulating oil as an arc cooling medium i.e., transformer oil.
The extinction of the arc is aided mostly by two processes:
- The hydrogen gas, for starters, has a high heat conductivity and thus cools the arc, assisting in the de-ionization of the medium between the contacts.
- Then the gas creates turbulence in the oil, forcing it into the area between the contacts, thereby removing the arcing products from the arc path. As a result, the arc is extinguished, and the circuit current is terminated.
Types of Oil Circuit Breaker:
There are two types of Oil Circuit Breakers based on the quantity of oil used, they are tabulated below:
|Bulk Oil Circuit Breakers||Minimum Oil Circuit Breakers|
|These circuit breakers consume a lot of oil.|
The oil must perform two functions: it must extinguish the arc when contacts are opened, and it must insulate the current conducting elements from one another and from the earthed tank.
|A limited amount of oil is used in these circuit breakers.|
Oil is only utilised for arc extinction in such circuit breakers, with the current-conducting components insulated by air, porcelain, or organic insulating material.
Advantages of Oil Circuit Breaker:
- The oil acts as a barrier between the live exposed contacts and the environment.
- Arcing produces hydrogen, which has good cooling qualities and aids in arc extinguishment.
- The oil in the vicinity of the arc provides a cooling surface.
Disadvantages of Oil Circuit Breaker:
- Oil is combustible and can result in a fire.
- When hydrogen is mixed with air, it can create an explosive combination.
- Oil becomes polluted by carbon particles during arcing, lowering its dielectric strength. As a result, it necessitates routine maintenance and replacement.
Application of Oil Circuit Breaker:
Oil circuit breakers are used in high-voltage applications such as power grids, substations, powerlines, and transmission and distribution systems, and can handle voltages up to 220 kV.
Air Circuit Breaker:
An air circuit breaker (ACB) is an electrical device that protects electric circuits from 800 to 10,000 amps from overcurrent and short circuits. These are typically utilised in low-voltage applications that are less than 450V. These systems can be found in Distribution Panels (below 450V). At a particular atmospheric pressure, an air circuit breaker is a circuit operation breaker that functions in the air as an arc extinguishing medium. Present environment offers a variety of air circuit breakers and switching gears that are stable, high-performing, and simple to install and maintain. Oil circuit breakers have been replaced entirely by air circuit breakers.
Advantages of Air Circuit Breaker:
The following are a few of the benefits of using an air circuit breaker:
- Re-closing facility with high speed
- Air circuit breaker is frequently used.
- Maintenance is reduced.
- Operation at high speeds
- Unlike oil circuit breakers, the risk of fire can be minimised.
- Contacts burn less due to consistent and short arcing time.
Disadvantages of Air Circuit Breaker:
The following are some of the drawbacks of using an air circuit breaker:
- The arc chute principle has a downside in that it is inefficient at low currents where the electromagnetic fields are weak.
- The chute’s extending and de-ionizing operation is not inherently less efficient at high currents, but the arc movement into the chute tends to slow down, and high-speed interruption is not always achieved.
Application of Air Circuit Breaker:
Air Circuit Breakers are used to control the auxiliary and industrial plants of power plants. Industrial plants, electrical machines such as transformers, capacitors, and generators are all protected by them.
- They are mostly employed to protect plants in areas where there is a risk of fire or explosion.
- In DC and AC circuits up to 12KV, the air brake principle of the air breaker circuit arc is applied.
- The high resistance power of air circuit breakers aids in raising arc resistance by dividing, cooling, and prolonging the arc.
- In the electricity sharing system, an air circuit breaker is also employed, with a range of up-to 15kV.
Vacuum Circuit Breaker:
A vacuum circuit breaker is a type of circuit breaker that uses a vacuum medium to quench the arc. In a vacuum chamber in the breaker known as a vacuum interrupter, the action of switching on and closing current carrying contacts as well as interrelated arc interruption takes place.
A vacuum circuit breaker is one that uses vacuum as the arc cooling medium in a circuit breaker because vacuum has superior arc cooling qualities and hence provides greater insulating strength. Because vacuum technology was designed for higher voltage uses, but it was not commercially practicable, this is acceptable for most normal voltage applications.
The breaker’s vacuum chamber is where current-carrying contacts and related arc interruption take place. A steel arc chamber is located in the centre of symmetrically positioned ceramic insulators in this interrupter. The vacuum pressure within a vacuum interrupter can be maintained at 10–6 bar. The performance of a vacuum circuit breaker is largely determined by the material chosen for current-carrying contacts, such as copper.
Advantages of Vacuum Circuit Breaker:
- Vacuum circuit breakers are smaller and have a longer lifespan.
- Energy is very low across the metalvapor arc due to the very low voltage.
- During and after the circuit breaker action, no gases are produced.
- These breakers have the unique ability to break any heavy fault current flawlessly just before the contacts reach a definitive open position.
- They are able to endure lightning strikes.
- These breakers have a distinct advantage over other breakers when the voltage is high and the current to be interrupted is little.
- In comparison to other interrupting devices, the cost is reasonable for small fault interrupting capabilities.
Disadvantages of Vacuum Circuit Breaker:
- The fundamental problem is that at voltages higher than 33 KV, it is uneconomical. At greater voltages, the breaker’s cost becomes prohibitive. Furthermore, small-scale production is uneconomical.
- When you consider all of the expenditures of operation and maintenance, the price is too costly.
- When the inductive or capacitive load is unplugged, it is easy to create over-voltage due to current interception, reignition, and other factors, therefore make sure to employ the appropriate over-voltage protection.
Application of Vacuum Circuit Breaker:
- The vacuum circuit breaker is the most reliable current interruption device for medium voltage switchgear. In comparison to other circuit breaker technology, it requires very little maintenance.
- Vacuum circuit breakers are used in outdoor applications with voltage levels ranging from 11 to 33 kV.
- Even though they have a limited rating of 60 to 100 kilo volt-amperes, they are suitable for the majority of rural applications.
- Vacuum circuit breakers are used as very high-speed making switches in many industrial applications due to their narrow gap and excellent recovery.
SF6 Circuit Breaker:
The arc quenching medium is Sulphur hexafluoride gas (SF6). SF6 is a gas with an electronegative charge. SF6 has a great proclivity for absorbing electrons. Arc is formed when contacts are opened in a high-pressure, SF6 gas flow. The gas captures free electrons in the arc and builds up enough insulating strength to extinguish the arc. It is especially useful for high-power and high-voltage applications.
Advantages of SF6 Circuit Breaker:
- Contact erosion is minimal due to the low energy.
- The dielectric and arc quenching properties of the gaseous medium SF6 are outstanding.
- Such circuit breakers have a very low arcing duration due to the SF6 gas’s better arc quenching characteristic. They can even interrupt much bigger currents.
- Unlike air-blast circuit breakers, these breakers operate quietly due to their closed gas circuit and lack of emissions to the atmosphere.
- Because SF6 is not combustible, SF6 breakers do not pose a risk of fire or explosion.
Disadvantages of SF6 Circuit Breaker:
- Due to the high cost of SF6 gas, these circuit breakers are quite expensive.
- Because SF6 gas must be reconditioned after each breaker action, additional equipment is necessary for refilling work.
- Because SF6 gas has been identified as a greenhouse gas, it may be damaging to people in the area where it is used.
Application of SF6 Circuit Breaker:
- These circuit breakers are suitable for a wide range of medium and high voltage applications, up to 800kV and above.
- Metal-clad and hybrid HV substations benefit the most from this medium.
- Applicable in all type of power stations (Generation, transmission and distribution sub stations).
DC Circuit Breaker Type:
HVDC Circuit Breaker:
HVDC (High Voltage Direct Current) circuit breakers are a type of circuit breaker that is specifically intended to safeguard HVDC circuits from fault current.
The arc quenching process, as previously mentioned, is a key feature that distinguishes DC circuit breakers from other types of breakers. Because the energy at zero crossing is zero, no arc can be generated at that voltage level, it is easier to break the circuit with an AC breaker. The voltage and current never go to zero in DC. As a result, when the contacts are separated, there is always a lot of voltage and current between them.
Advantages of HVDC Circuit Breaker:
- HVDC circuit breakers have a compact design and a high breaking and making capability.
- HVDC circuit breakers are extremely reliable and high insulation level.
- HVDC circuit breakers require minimal maintenance.
Disadvantages of HVDC Circuit Breaker:
- When compared to AC equipment, the converters utilised at both ends of the line in HVDC are quite expensive. The converters have a limited capacity for overload and require reactive power, which must be provided locally.
- Each converter requires filters on the AC side, which adds to the price.
- The majority of electric power is used at low voltage. In the case of DC, voltage conversion is not simple.
Application of HVDC Circuit Breaker:
HVDC Circuit Breakers are used in:
- DC drives or cycloconverters
- Solar energy, energy storage, or a backup power supply
- Stations for charging batteries
- Exploration and mining (Hoists, grinding mills, electric mining haul trucks)
- Chemical processing plants (electrolysis)
- Marine works.