Air Circuit Breaker and it's Circuit Development.

Having had covered with all the basic terminology related to ACB, thus further in this lecture we shall learn about;

1. Operating an ACB

   1. ACB ON & OFF methods

   2. Technical terms used for operating an ACB (Close & Open)

2. Two way of operating an ACB

   1. Electrical methods

   2. Manual method

3. How a ACB mechanically closed? ( Technical steps mandatory to ON the ACB)

4. Importance of Springs in ACB

   1. Closing spring

   2. Opening spring

As we learned about operating an ACB in two different methods manually and electrically in previous lecture, as so in this lecture we shall discuss its Manual method 

1. The mandatory steps required to ON the ACB manually 

2. Manually Spring charging method

3. Indications of ACB on breaker facia

   1. ACB open / close

   2. ACB ready to Close

   3. Spring Charged / Discharged

As we come to know how can the ACB ON & OFF by manual method, hence now in this lecture we shall familiarize with the electrical methods to operate an ACB;

1. ACB differentiated according to there spring charge mechanism

2. Methods & mandatory steps need to charge the closing spring of ACB electrically

3. Difference between manual & electrical operating methods of air circuit breaker

4. Advantages of electrically operated ACB

5. Add on equipment's required in manual ACB to make it comfy for electrical operations 

   1. Motor mechanism

   2. Closing coil 

   3. Tripping coil

As we learn the add on technical equipment's mandatory in an Electrically Operated ACB, in this lecture we shall specifically learn about that particular equipment's

1. Spring charging method of ACB through motor mechanism

2. Limit switch require for the protection of springs

3. A very simple and basic circuit diagram including theses accessories to understand the working in technical manner

   1. Motor for spring charge

   2. Limit switch to protect the spring

   3. MCB ( single or double pole ) used against the protection of short circuit.

   In this lecture we'll see a very basic and small part of circuit diagram however development on these have been taken up in the further lectures.

As we know for to operate an ACB electrically a motor mechanism is used to charge the spring, thus in this lecture we shall learn how an ACB is electrically closed.

1. Closing coil of ACB

2. Remote operation of ACB

3. Circuit diagram covering the concepts

   1. Wiring of closing Coil

   2. Closing commands to closing coil

Did you know?

Tripping is more important then closing of ACB.....

Thus after learning how an electrical ACB is close, let us learn about how an Electrical ACB trips in an abnormal condition.in this lecture we shall discuss about;

1. Principle of electromagnetism of power contactors

2. Difference between Electrical contactor & Circuit breaker

3. Tripping coil operation of ACB

4. Remote operation of a tripping coil

5. Basic control circuit of trip coil of ACB

In addition to the previous lecture, here we shall discuss more on the electrical energization of coils used in ACB that is;

1. Closing coil used to close(ON) the ACB

2. Tripping coil used to trip(OFF) the ACB

3. The terms related to closing spring of an ACB

4. The terms related to tripping spring of an ACB

As from the previous lectures we thoroughly understood the working of an Electrically operated ACB

In this lecture we have covered ;

1. The mechanically interlinked spring of Manual &  Electrical ACB

2. Conversion or add on accessory to convert a manual ACB to electrical one

3. Advantages of electrical ACB over manual one

4. A short recap of basic two circuit of closing & tripping

   
   

Did you know?

Releases are such a device that provides intelligence to ACB, in simplest terms we can say that ACB works smartly and more reliable when releases added in ACB thus in this lecture we shall study;   

1. What is releases

2. Types of releases

   1. Shunt release

   2. Undervoltage release

   3. Thermal magnetic and electronic type release

3. Shunt Release also known as shunt or shunt trip coil.

4. What is a shunt trip coil?

   1. Rated control supply to the shunt coil

   2. Logical conditions required for tripping of ACB

5. Circuit diagram explanation of shunt trip coil of ACB

   1. Several conditions under which tripping can take place

   2. The function and co-ordination within the contacts in fault conditions

In addition to the above lecture, let us learn about the undervoltage release of ACB, In this lecture you shall learn about;

1. What is an undervoltage release

2. Under which condition the UV coil or UV release is used in ACB

3. Main function of a UV coil in ACB

4. Connection of UV coil in  a circuit wrt ACB

5. Various rated UV coil used for the rated control supply

6. Difference between a shunt trip release & an undervoltage release

In this lecture we shall learn about the Automatic breakers that is;

1. What is an Automatic breaker?

2. What protection features used in Automatic breakers?

3. What is Thermal magnetic and Electronic releases?

4. Protection features of electronic trip units (ETU)

   1. LSING features

      1. L is overload protection

      2. S is short circuit protection

      3. I is short circuit instantaneous protection

      4. N is neutral conductor protection

      5. G is Earth fault protection

      6. ETU settable trip time unit

5. Co-ordination of Air circuit breaker in fault condition.

Welcome to the section 4 of ACB's basics & it's working circuit

After having the brief description of ACB  and its accessories lets see how it implies in the circuit or schematic diagram, as its more important to learn the blocks and development of the circuit for more suitable understanding, thus in this lecture we shall learn;

1. Block representation  of schematic drawing of ACB, that includes 5 sub-circuits

   1. Power circuit

   2. Metering circuit

   3. Motor & closing circuit

   4. Tripping circuit

   5. Indication circuit

However in this lecture we shall cover the blocks of power & metering circuit of ACB,

The advantage of learning the block representation is that you shall easily develop a circuit as you get familiarize with all the components and accessories situated or assembled in the circuit diagram.   

Did you know we can modify the ACB as per the requirement,

As we learnt that ACB's come in 3 & 4 pole, Fixed & Drawout type,

(EDO - electrically drawout type ACB, MDO - manually drawout type ACB)

Thus in addition to above lecture we will the learn the representation of power contacts of ACB

1. 3P manual fixed ACB without release, but with shunt trip coil

2. 3P manual fixed ACB without release and without shunt trip coil

3. 3P MDO ACB without release, but with shunt trip coil

4. 3P MDO ACB without release, and without shunt trip coil

5. 3P Electrical fixed ACB without release, but with shunt trip coil

   
   

   
   

   
   

In this lecture you shall be learning about the associated electrical control circuit of the ACB that includes there

• Contact arrangements

• Control voltage

• Wiring connections between the breaker & other electrical components

Thus from this lecture you may get to know a clear & concise understanding of  the functional relationship between the various components , thus control circuit of ACB usually comprise

1. The motor & closing circuit

2. Tripping circuit

3. Indication circuit

the supply control voltage & the  supply distribution scheme  for such control circuit is been thoroughly explained in this lecture.

In this lecture we shall cover the block representation of motor & closing coil of  ACB, it represent the detailing information about;

1. Supply voltage

2. Block representation of closing coil

3. Block representation of Spring charging motor & limit switch

Note : Tripping coil blocks & contacts representation is been explained in lecture 3.1

In this lecture we shall learn about the indication circuit ,that how it helps to provide the indication of ACB status in various position such as

• ACB ON, OFF or TRIP

• ACB is Test or Service position

• ACB's Spring charged or Ready to close   

However this blocks of indication circuit represents,

1. Auxiliary contacts of ACB

2. Trip signaling contact of ACB

3. The indicating lamps 

4. Examples of multiplied Aux. contacts of ACB

As we know that we have a source of supply voltage in two condition that is AC or DC, In fact DC source supply is more reliable for control circuit supply voltage, HOW?

Thus, in this lecture we have covered the variation of supply voltage for the control circuit of ACB here you we will get to know

1. The AC & DC supply source fed for the control circuit

2. External source used to tap the voltage

3. Tapping of the voltage from the line side of the breaker

4. Relevant supply voltage unit required for such control circuits of ACB   

In addition to the above lecture we have covered

1. The condition applicable for supply voltage

2. The merits & demerits of supply voltage tapping

3. The effect of the supply voltage tapped from the line side of the breaker to the the other circuit

4. Convention & Terms required for such supply voltages

5. Project specification need or example of control supply voltage for more then one accessories assembled in ACB

Signaling contacts helps the ACB to provide signals through Aux. contacts in various condition thus in this lecture we shall study about;

1. Depiction of auxiliary contacts of ACB

   1. NO  (normally open)

   2. NC (normally close)

   3. CC ( changeover contact)

2. The signaling contact comprise various signaling in indication circuit of ACB that is

   1. Spring charge signaling contact

   2. The ready to close contact

   3. Fault trip signaling contact

3. The signaling contacts functions toward the indicating lamp of ACB.

   however a these all topics are explained with a very simple & understandable example

In this growing era of technologies the need has became that ACB too need to communicate with SCADA & DCS system, is this so possible?

In this lecture you will get to know about the communication capable ACB

1. The modules used for communication purpose in ACB

2. Explanation on communication protocols

   1. Modbus

   2. Ethernet

   3. Profibus

   4. Profinet

   5. ETU used for such protocols

3. The current & voltage module used for parameters to convey ACB communication

4. ACB accessories for communication & control 

As we know that there are various accessories in ACB that tends to make it as a communication capable ACB from among them position switch is one of the important accessories of ACB ,

In this lecture we shall learn;

Position switch of a withdrawable or drawout ACB & they provide signal for

• ACB in service position

• ACB in test position

• ACB in Isolated or disconnected position

You shall also learn the status of the main circuit contact &  control circuit contact in these position.

In this lecture we shall learn about the ACB with or without Release & Protection relay

1. Concept of breaker with releases but with external protection relays

2. The importance of relays

3. Protection feature of ACB without release but with relays

4. Different types of relays

5. Circuit diagram explaining the connection of relays

Welcome to the section 5,

Since now we have covered all the technical & physical aspects of ACB and also gone through the block representation of the various circuits, now let us learn to build the circuit thus in this course we shall develop a circuit step by step that includes;

1. Basic electrical schematic for an ACB

2. Graphical representation development includes

   1. 3 Pole fixed manual breaker

   2. Drawout block development for withdrawable manual breaker

   3. Motor block development for spring charge for withdrawable electrical breaker

   4. Shunt coil block development for electrical tripping

hence we covered a complete basic ACB power circuit  with neutral connection for an ACB power outgoing feeder   

Here in this lecture we shall learn the basic development of closing circuit of ACB as well as the control supply

1. Principle of spring charge motor mechanism before closing of an ACB

2. Development of general symbol block of closing coil & spring charge motor for ACB

3. Explanation on control voltage to closing coil control circuit

4. Control supply for circuit breaker control circuit

In addition to the previous lecture, here in this lecture we shall see more development & modification of closing coil circuit of ACB with TNC switch, and explained with an example situation.

In this lecture we shall learn to develop a trip coil circuit

1. Symbol block development of a trip coil

2. Modification of trip coil circuit with TNC ( trip neutral close) contact of breaker control switch

3. Definition of TNC (trip neutral close) switch

4. Working &  wiring of trip coil circuit of ACB.

In this lecture we shall learn about the development of indication circuit, thus wrt to ACB's indication components following topics are been covered;

1. Symbol block of  ACB auxiliary contact

2. Development & wiring connection of ACB Aux. contact for indication purpose

3. Wiring of indication accessories such as  indicating lamps to the Aux. contacts

4. Explanation on indicating lamps with an example within the circuit

5. Explanation of auxiliary control contactor

Short recap of basic 3P EDO ACB, without release that is the power & control circuit ( Closing, tripping & indication circuit)

Here in this lecture we have seen a very basic closing coil circuit however its been modified with local remote selector switch & position switch development of these circuits have taken in further lectures.

This lecture covers modified closing circuit with the local / remote selector switch on the condition based on local closing or remote closing of an ACB, you shall learn;

1. Symbol representation & wiring of 1 Pole 2 way selector switch in closing circuit of ACB

2. Function of 1 Pole 2 way selector switch in closing of ACB for local path

3. Function of 1 Pole 2 way selector switch in closing of ACB for remote path

As we learn in the lecture 28 (4.7.2) the working of position switch in different conditions of an ACB,

thus in this lecture we have modified closing circuit of ACB with the position switch, thus here we shall learn

1. Graphical representation of position limit switch

2. Configuration related to the contacts of position switch

3. Test position configuration

4. Modification of closing circuit with test position

5. Working of test position in local & remote path within the closing circuit wrt to TNC switch 

In this lecture we shall learn the modification of closing circuit in service position, following are the conditions covered:

1. Closing circuit command from local path in service position

2. Closing circuit command from Remote path in service position

3. Closing commands of local/remote path desired from local/remote selector & TNC switch.

4. Conditions of closing command from local/remote of ACB in test position

Is that possible to give ACB closing command when in test position?

The answer is No, so how to solve this?

In this lecture we will learn how to overcome this undesired condition.

1. The condition of closing the ACB in test position

2. The condition of add on service position limit switch in remote path

3. The working of service position limit switch for safety purpose

4. The working of connection wire

5. The provision of future interlocks used in the circuits

6. The correlation between the future interlock and connection wire. 

From this lecture you will learn;

1. Condition before closing an ACB in fault condition

2. Condition of tripped sense in fault condition sensed by an external relay

3. Condition of tripping an ACB without release but with external overcurrent protection relay

4. Connection between the power circuit with external protection relay within the control circuit

5. Working of relay in fault condition.

In this lecture we will learn about:

1. Terms related to closing coil

2. Condition of closing coil based on TNC switch /remote close

3. Modification of closing circuit with auxiliary contact with respect to continuity of supply to the closing coil

4. The proportional working of ACB and closing coil within the closing command

   
   

Did you know that tripping of ACB has higher priority then closing,

As in the previous lectures we modified the closing circuit to certain condition as per requirment in the same way in this lecture we will learn to develop or modify a basic trip circuit furtherly as per required condition i.e.:

1. Remote trip command

2. Conditions of tripping command of ACB in service poition

3. Impact of ACB tripping command in test position

4. Conditions applicable for future trip of ACB

In addition to the previous lecture, in this we will learn about

1. What are the condition based on trip coil in the circuitry

2. How does a trip coil maintain its supply

3. Working of a trip coil

4. The function of its auxiliary contact within the trip command from future or remote

Can a trip coil too get faulty?

The anwser is yes for this we will have to check the healthiness of a trip coil in its circuitry

So in this lecture we have modified the trip circuit such that

1. Check the healthiness of trip coil

2. Connection within the trip coil

3. Working of circuits when health check of trip coil is performed

After having had a brief description on trip coil the circuit undergoes a provision to trip the ACB in an undervoltage condition, in this case the UV release or UV coil is used, however more on UV coil is explained in section 3, thus in this lecture we will learn:

1. UV coil connection in the circuitry

2. UV coil conditions of tripping or closing the ACB mechanically in an undervoltage condition

3. Working of an undervoltage release