AIR BLAST CIRCUIT BREAKER

            AIR. CIRCUIT BREAKER

Maintenance 

Different Parts 

ACB Test

 ACB Check

ACB Mechanism

 Full Enclosure Fitted

 MECHANICAL PARTS 

WIRING DIAGRAM

IDMT RELAY FOR ACB

FAULT FINDING 

 MECHANISM

TRIP

ANTI PUMP RELAY

DESCRIPTION

ACB and VCB 

Case Circuit Breaker. ACB is stands for Air Circuit Breaker. VCB is stands for Vacuum Circuit Breaker. ... The Vaccum Circuit Breaker which use ark quenching device as a vaccum and used for 415 volts.

Function 

The main function of air circuit breaker is to:

– Open the circuit automatically when a fault occurs. Faults can be of various types – under or over voltage, under or over frequency, short circuit, reverse power, earth fault etc. – The main feature of ACB is that it dampens or quenches the arcing during overloading

 Type of circuit breaker 

The most widely used electrical circuit breakers for domestic electrical connections are Miniature circuit breakers (MCBs) ,Residual current circuit breaker (RCCB) and Mounded Case Circuit Breaker (MCCB)Following are some basic guide on these domestic Circuit Breaker

Use

Air Circuit Breaker (ACB) is an electrical device used to provide Overcurrent and short-circuit protection for electric circuits over 800 Amps to 10K Amps. These are usually used in low voltage applications below 450V. We can find these systems in Distribution Panels (below 450V).

 types of air circuit breakers 

As we said earlier that there are mainly two types of ACB, plain air circuit breaker and air blast circuit breaker. But the later can be sub divided further into three different categories.

ACB safety

Electrical

Safety Device: Air Circuit Breaker (ACB) ... One of the important safety devices used for ship's generator is Air Circuit Breaker (ACB). Air circuit breaker is designed to overcome the defects and safeguard the machine before it breakdowns.

 VCB 

In HT supply system make-break operation creates huge spark due to high voltage, Here current is low but the potential difference charge the surrounding area molecules of air or else. They gets charge during switching operations and makes huge arc , which required to extinguished

Arc quenching

What is quenching an arc? When the reed contacts open they break a circuit. If there is a voltage and current present when the contacts open they will stop the current flow. ... Quenching the arc refers to the stoppage of the arc and/or metal transfer.


 Air circuit breaker

Air Circuit Breaker definition
It is a circuit breaker with compressed air as arc quenching medium to exterminate the arc produced when the contacts are separated. So this is called Air Circuit Breaker. The air circuit breaker is used for the voltages less than 3 KV.

 Air breaker switch

An
“air break switch' is a switchgear device that uses air as the dielectric. Air Break Switches (ABS) are widely installed throughout distribution networks for use as both isolation or switching points. They are usually employed in outdoor installations.

Type of breaker 

Circuit breakers have markings stamped on the side of them and are usually located inside the panel cover door. There is a label that will tell you what type of breaker is needed for installation in that particular panel. On the market, there are home and commercial circuit breaker panels.

Test 

3 Basic Electrical Tests for Medium-Voltage Circuit Breakers
Contact resistance test. The main contacts and primary stabs need to be checked periodically to detect abnormal wear, inadequate lubrication, and loose pivot points inside the circuit breaker. ...
Insulation resistance test. ...
Dielectric withstand voltage test.

 LT breaker

L.T Circuit Breaker. A circuit breaker is an automatically- operated electrical switch designed to. protect an electrical circuit from damage. caused by overload or short circuit

3 types of circuits

Electric Circuit -Types of Electric Circuit. There are 5 Main Types of Electric Circuit – Close Circuit, Open Circuit, Short Circuit, Series Circuit and Parallel Circuit

 ACB and MCCB

Difference
between MCCB and ACB. MCCB stands for Molded Case Circuit Breaker. ACB stands for Air Circuit Breaker. MCCB is used at the load side of the circuit in order to break the circuit from load side in case of any fault which can cause damage to the circuit

 VCB breaker

A
vacuum circuit breaker is a kind of circuit breaker where the arc quenching takes place in vacuum medium. The operation of switching on and closing of current carrying contacts and interrelated arc interruption takes place in a vacuum chamber in the breaker which is called vacuum interrupter.

 Use ACB instead of Mccb

The rating of the ACB is higher than the MCCBs. Due to this high current rating a ACB is used in the circuit with a larger circuit current. The tripping thresholds can be adjusted easily in the MCCB. This parameter makes the MCCB favorable in different circuits over other circuit breakers.

 Use VCB instead of ACB

Due to the integrity of Vacuum Bottles compared to ACB. Plus the VCB are way less maintenance demanding compared to ACB which demand more frequent maintenance on them. Number of operations which VCB can withstand are much more. No arc chutes issue and many more advantages.

 Spark and Arc

a spark is what you get when the air breaks down and electrons jump the gap between conductors discharging the charge that led to the potential. ... An arc is a high-power spark. Generally, we call it an arc when it's 1) pretty big, and 2) has enough power to heat the gas it traverses into a plasma.

 Advantages of sf6 circuit breaker

SF6
Circuit Breakers Advantages: Excellent insulating, arc extinguishing, physical and chemical properties of SF6 gas is greater advantage of SF6 circuit breakers. The gas is non-inflammable and chemically stable. The decomposition products are non-explosive i.e, rhere is no risk of fire or explosion.

 Arc quenching in MCB

The
final arc extinction or arc quenching in circuit breaker is achieved by rapid increase of the dielectric strength in the medium between the contacts so that reestablishment of arc after zero crossing cannot be possible

 Sf6 circuit breaker
SF6 circuit breakers Applications:

A typical SF6 circuit breaker consists of interrupter units each capable of dealing with currents up-to 60 kA and voltages in the range of 50—80 kVA number of units are connected in series according to the system voltage.
 VCB breaker work

A vacuum circuit breaker is a kind of circuit breaker where the arc quenching takes place in vacuum medium. The operation of switching on and closing of current carrying contacts and interrelated arc interruption takes place in a vacuum chamber in the breaker which is called vacuum interrupter.

Testing 

This maintenance includes the testing of the insulation medium to verify that it has the proper qualities required to dielectric protection and heat transfer abilities. Electrical tests consist of the insulation resistance test, contact resistance test, over-potential (hi-pot) test, and circuit breaker timing test.


 Air circuit breakers use

Air Circuit Breaker (ACB) is an electrical device used to provide Overcurrent and short-circuit protection for electric circuits over 800 Amps to 10K Amps. These are usually used in low voltage applications below 450V. We can find these systems in Distribution Panels (below 450V).

 Types of air circuit breakers 

As we said earlier that there are mainly two types of ACB, plain air circuit breaker and air blast circuit breaker. But the later can be sub divided further into three different categories.

Why we are using VCB in HT side?

In HT supply system make-break operation creates huge spark due to high voltage, Here current is low but the potential difference charge the surrounding area molecules of air or else. They gets charge during switching operations and makes huge arc , which required to extinguished.

 LT breaker

L.T Circuit Breaker. A circuit breaker is an automatically- operated electrical switch designed to. protect an electrical circuit from damage. caused by overload or short circuit.

 VCB breaker

A vacuum circuit breaker is a kind of circuit breaker where the arc quenching takes place in vacuum medium. The operation of switching on and closing of current carrying contacts and interrelated arc interruption takes place in a vacuum chamber in the breaker which is called vacuum interrupter.

 Test of air circuit breaker

3 Basic Electrical Tests for Medium-Voltage Circuit Breakers
Contact resistance test. The main contacts and primary stabs need to be checked periodically to detect abnormal wear, inadequate lubrication, and loose pivot points inside the circuit breaker. ...
Insulation resistance test. ...
Dielectric withstand voltage test.

 use HT panel

HT Panel is like LT Panel except that it is used for high tension cables. These panels are used in commercial buildings and industries where there is fluctuation in voltage and power supply. The electrical load required by a unit depends upon the type of machineries, cooling plants and other devices installed.

Advantagesof sf6 circuit breaker

SF6 Circuit Breakers Advantages:
Excellent
insulating, arc extinguishing, physical and chemical properties of SF6 gas is greater advantage of SF6 circuit breakers. The gas is non-inflammable and chemically stable. The decomposition products are non-explosive i.e, rhere is no risk of fire or explosion.

Types of ACB 

As we said earlier that there are mainly two types of ACB, plain air circuit breaker and air blast circuit breaker. But the later can be sub divided further into three different categories. Axial Blast ACB.

ACB safety

Electrical Safety Device: Air Circuit Breaker (ACB) .​.. One of the important safety devices used for ship's generator is Air Circuit Breaker (ACB). Air circuit breaker is designed to overcome the defects

 Sf6 Application

SF6 circuit breakers Applications:
A typical SF6 circuit breaker consists of interrupter units each capable of dealing with currents up-to 60 kA and voltages in the range of 50—80 kVA number of units are connected in series according to the system voltage.

 Function  sf6 circuit breaker

Instead of oil, air, or a vacuum, a sulfur hexafluoride circuit breaker uses sulfur hexafluoride (SF6) gas to cool and quench the arc on opening a circuit. Advantages over other media include lower operating noise and no emission of hot gases, and relatively low maintenance.

VCB and sf6 circuit breaker

Difference between VCB and SF6 circuit breaker.
In VCB or vacuum circuit breakers vacuum is used for arc quenching. The contacts of the breaker are kept in vacuum inside an airtight chamber. ...

On the other hand in SF6 circuit breakers SF6 gas is used as the insulating medium


Sf6 used in Circuit breakers
In an SF6 Circuit breaker, sulphur hexafluoride gas is used as the arc quenching medium. The sulphur hexafluoride gas (SF6) is an electronegative gas and has a strong tendency to absorb free electrons. ... The gas captures the conducting free electrons in the arc to form relatively immobile negative ions.

 Sf6 use GIS

SF6 is used in GIS at pressures from 400 to 600 kPa absolute. The pressure is chosen so that the SF6 will not condense into a liquid at the lowest temperatures the equipment experiences. SF6 has two to three times the insulating ability of air at the same pressure.

Sf6 explosive

Sulfur hexafluoride SF6 gas hazards
Sulfur hexafluoride (SF6) is colorless, odorless, heavier than air and is not considered as toxic. ..
. Sulfur hexafluoride has no lower and upper explosive limits but can severely react with disilane and form a dangerous explosive gas mixture.

 Use sf6 in circuit breaker

SF6 Circuit Breaker
Due to high electronegativity, it has a high affinity for absorbing free electrons. It absorbes electrons to form a negative ions. .
.. Due to these unique properties of this gas, SF6 circuit breaker is used in a complete range of medium voltage and high voltage electrical power system.

 GIS and AIS

GIS high voltage substation engineering uses the gas sulfur hexafluoride for insulation, whereas
AIS uses air insulation in a metal-clad system.
Sulfur hexafluoride is five times heavier than air and offers excellent extinction behavior. ... GIS systems use fixed, mounted circuit breakers.

 Sf6 gas heavier than Air

Clean SF6 gas is an inert, stable, colorless, odorless, nontoxic, nonflammable gas.
It is approximately five times heavier than air and will displace air in confined areas.
SF6 gas contains no oxygen and will not support life.

Disadvantages GIS over AIS

Disadvantages
More space is required compared to GIS.
Vulnerable
to faults since the equipment are exposed to the external elements such as human intrusion, pollution, deposition of saline particles, lightning strikes and extreme weather conditions.
More maintenance requirements, thus leading to high costs

Air insulated substation

An air-insulated substation (AIS) is one where the main circuit potential is insulated from the ground by air using porcelain or composite insulators and/or bushings. ...
AIS is the most common type of substation, accounting for more than 70% of substations all over the world

 Switchgear and Types

Switchgear. ... Switchgear has two types of components:
Power-conducting components:
 These conduct or interrupt the power flow; such as switches, circuit breakers, fuses, isolators, relays, lightning arrestors, and so on

LV and MV switchgear

Thus, the term LV switchgear collectively refers to H.R.C. fuses, low voltage circuit breakers, offload electrical isolators, switches, earth leakage circuit breakers, molded case circuit breakers (MCCB) and miniature circuit breakers (M.C.B.).
 That is, all accessories that are required in protecting the LV system.

Difference LV ,MV and HV

Low
Voltage (LV) is 120V and under. Medium Voltage (MV) is 240V to 360V.
High
Voltage (HV) is anything above 600V. Extra High Voltage (EHV): 1000V and up.

 Low voltage (LV) electricity

Low voltage (LV) electricity means electrical energy at voltages exceeding 32 Volt AC
or 115 Volt DC, but not exceeding 1000 Volt AC or 1500 Volt DC.

Difference between LT and HT cable

Low
tension cables have a lower rating where as high tension cables have a higher rating [3.3kV].
 Both cables are used in industrial setup and applications, but LT cables are generally used in applications revolving
around the 1.1kV range and HT cables are used mainly in power transmission and its distribution.

 Calculate HT current

HT Current =(1250*1000)/(1.732*22000)=1250000/38104=32.80 Amp. LT Current=(1250*1000)/(1.732*415)=1250000/718.78=1739.057 Amp.

 Let's assume that it is a step up transformer then the LT winding is referred as primary winding and the HT winding is referred as secondary winding.

ACB use

Air Circuit Breaker (ACB) is an electrical device used to provide 

Overcurrent and short-circuit protection for electric circuits over 800 Amps to 10K Amps. 

These are usually used in low voltage applications below 450V.

 We can find these systems in Distribution Panels (below 450V).

Backfeed a Breaker

The

simplest explanation for backfeed is when power flows in the opposite direction from its usual flow 

or when voltage is present on a conductor or associated equipment after it has been disconnected from its normal source.

Voltage is safe

30 volts

In industry, 30 volts is generally considered to be a conservative threshold value for dangerous voltage. The

cautious person should regard any voltage above 30 volts as threatening, not relying on normal body resistance for protection against shock.

 440v 3 phase

3 phase system is expressed with line voltages.

 The line votage is 440 volt. Also the voltage between any one phase and neutral for a 3 phase system is 240 volts. 

440V in 3 phase system is line to line voltage if you calculate per phase voltage then you will get approximate same value as for 1 phase system.

Dangerous AC or DC

AC is more serial killer as AC with less frequency (50 Hz in EU and 60 Hz in US) is more dangerous than the DC having the same level of voltage. 

In other words, 230V AC (or 120V AC) is more dangerous than 230V DC or 120V DC respectively.

 Dangerous 220v AC or 220v DC

220V a.c is more dangerous than 220V d.c this is because 

220V a.c has peak voltage of 220 ×√2=311V, 

while 220V d.c has a peak voltage of 220V only .

 Lightning

Lightning cannot be AC, since the wave shape of Lightning current is not sine-wave shaped voltage. 

A typical lightning current waveform looks something like this as shown below. 

This complete event (A, B and C) is a single strike.

 Therefore, Lightning is neither DC nor AC cannot be AC, since the wave shape of Lightning current is not sine-wave shaped voltage.

3 types of lightning

There

are three primary types of lightning which include: 

cloud-to-ground (the most commonly known type), 

cloud-to-air, and

 cloud-to-cloud.

 With cloud-to-ground lightning, the rapid discharge of lightning is a channel of negative charge that is attracted to the positively charged ground.

Is it safe to watch TV during thunderstorm

It isn't dangerous to watch TV during a thunderstorm, but the electronics in a TV set are vulnerable. 

If you have to make a telephone call, use a mobile phone detached from its cable rather than a landline device. O

resulting from a lightning strike may follow electrical conductors into the handset

Should you not do during lightning

Safety precautions indoors

Avoid water during a thunderstorm. Lightning can travel through plumbing.

Avoid electronic equipment of all types. 

Lightning can travel through electrical systems and radio and television reception systems.

Avoid corded phones. ... No

Avoid concrete floors and walls

 Safe from lightning in a house

Myth: If you are in a house, you are 100% safe from lightning.

 Fact: A house is a safe place to be during a thunderstorm as long as you avoid anything that conducts electricity. This means staying off corded phones, electrical appliances, wires, TV cables, computers, plumbing, metal doors and windows.

Circuit breakers work

A

circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected.

 Maintain a circuit breaker

Molded case Circuit Breakers should be exercised at least once per year. Routine trip testing should be performed every 3 to 5 years. 

Low voltage

Circuit Breakers should be inspected and maintained every 1 to 3 years, depending on their service and operating conditions.

What is the difference between RCB and MCB?

The main difference between MCB, RCCB, and Isolators

ISOLATOR

are generally used in power system while on the other hand, 

MCB

is the circuit breaker. ... Whereas, on the other hand, residual current device protects the life-threatening problems. 

RCCB

detects the leakage current and protects from the electric shock.

 Circuit breakers work

A circuit breaker is an operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected.

Difference between RCB and MCB

The main difference between MCB, RCCB, and Isolators

Isolators are generally used in power system while on the other hand,

 MCB

is the circuit breaker. ... Whereas, on the other hand, residual current device protects the life-threatening problems. 

RCCB

detects the leakage current and protects from the electric shock

In

ACB the arc is initiated and extinguish in substantially static air in which the arc moves. Such breakers are used for low voltages, generally up to 15KV and rupturing capacities of 500MVA. ACB has several advantages over the oil, as an arc quenching medium.

Plain Break Type Air Break Circuit Breaker :- 

It is the simplest one in which contacts are made in the shape of two horns. The air initially strikes across the shortest distance between the horns and is driven steadily upwards by the convection currents caused by heating of air during arcing and the interaction of the magnetic and the electric fields

Air Chute Air Break Circuit Breaker :-

 The

normal arrangement of air-chute air break employed for low and medium voltage circuits . There are two sets of contacts called the main contacts and arcing or auxiliary contacts.

Magnetic Blow out Circuit Breaker :-

Air

circuit breakers are used in the circuits having voltage up to 11 KV, the arc extinction is accomplished using magnetic field provided by the current in blowout coils connected in series with the circuit being interrupted.

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Applications of Air Break Circuit Breaker :-

Air

break circuit breaker is suitable for the control of power station auxiliaries and industrial plants. They do not require any additional equipment such as compressors, etc. They are mainly used in a place where there are possibilities of fire or explosion hazards.

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