WHAT ARE CIRCUIT BREAKERS?TYPE OF CIRCUIT BREAKERS?

CIRCUIT BREAKER:

Today we will learn about what are circuit breakers? Type of circuit breaker and their operation and principle their uses.

INTRODUCTION OF CIRCUIT BREAKER

We learn about circuit breaker and their types. A most commonly major part of the electrical. So this article describe useful to understand easily and simply for students and others.

In all electrical circuits are used circuit breakers. It is a protection device that protects the electrical circuit. it protects the distribution line, Transformer, Small and medium size of motors, lighting circuit, generating substation,s and power plants. The commercial circuit breakers are build up 600A, 500A, and 100A.

 WHAT ARE CIRCUIT  BREAKERS?

A circuit breaker is a mechanical device that is performed as open and close contact. When current will be high or fault condition. it means the electrical circuit is in abnormal condition then the circuit breaker opens and cut-out the circuit. Now the circuit is in the normal condition we restored them with close contact. A Circuit breaker is an also a switching device which operates on normal and abnormal condition of current. Its switching function protect the circuit and protect to damage to another device. Design of circuit breaker automatic trip in abnormal condition or over current. Circuit breaker follows some duties 

1. It carries a full load current without overheating and damage.

2. It opens in abnormal conditions just like overcurrent or fault.

3. A load in normal condition circuit breaker will be close.

4. Circuit breaker only trips depending upon their design or their selectivity range.

 

The circuit breaker cuts out the current according to its specified range. If we take a circuit breaker that exceeds the current capacity, it does not prevent overcurrent and destroys the entire circuit, so we have to select the circuit sitting The circuit breaker of the correct range should be used according to the prescribed current. When a fault occurs in a circuit, the circuit breaker changes it and separates the circuit from the fault, and prevents it from getting damaged.

The circuit breakers are rated in terms of maximum voltage number of poles frequency maximum continuous current-carrying capacity e maximum interrupted. Circuit breakers are also rated in MVA which is the product of interrupted current rated voltage.

OPERATION AND PRINCIPLES

A circuit breaker is consists of fixed and moving contact when a normal condition both are touching each other and current flow continuously. whenever a fault occurs then the tripping coil energized and moving contacts pressurized to pull open the contacts and protect to damage is called abnormal condition in this condition circuit broken from the main circuit.

CIRCUIT BREAKER

Properties of circuit breakers

1. High dielectric strength

2. Noninflammability

3. High thermal stability

4. Commercially available at moderate cost

Arc extinction of circuit breaker-

There are two methods of arc Extinction 

1.High Resistance Method-

In this method increasing the value of resistance with time.This method is employed in DC circuit breaker and low to medium power.Resistance can be increase by

A) Reducing the concentration of the ionized particles.

B) Increase arc length 

C)  Splitting the arc

D) Reducing the arc x- section area

2.Low Resistance or Zero Point Method-

In this method decreasing the value of resistance and current is zero. This method is employed in AC circuit breaker and moderates to high power.Resistance can be Decrease by

A) High pressure 

B) Cooling

C) Blast effect 

Arc, Restriking, and recovery voltages-

The voltage across the contacts during the arcing period is known as Arc voltage.

Rate of Rise of Restriking Voltage (RRRV)-

RRRV is obtained by drawing a straight line through zero and tangential.

Current Chopping -

In circuit breaker when low inductive current, the current falls to zero then natural current become zero.

Arc, Restriking, and recovery voltages

TYPE OF CIRCUIT BREAKERS

The most commonly used circuit breaker follows 

1.Oil circuit breakers 

2.Low voltage air circuit breakers 

3.Air blast circuit breaker 

4.Vacuum circuit breakers 

5.Sulphur hexafluoride sf6 circuit breaker

 Rating of circuit breaker-

The circuit breaker is formed mainly three types of rating 

1.Breaking capacity  

2. making capacity

3. short time duty

Breaking capacity- 

It is generally expressed in terms of MVA ad is equal to the product of rated breaking current in amperes rated voltage in KV and factor which depend upon a number of phases.

Breaking capacity=Phase(single-phase or three-phase) VIx1/1000000

Making capacity-

 It is a maximum possibility of the read circuit breaker is closed under short circuit conditions the making capacity of the circuit breaker depends upon the effect of electromagnetic force which is proportional to the square of the peak value of making current.

Making a capacity = 2.55 x symmetrical breaking capacity

Short time rating- 

Short time rated current is the current that can safely be applied with the circuit breaker in its normal condition

Normal current rating -

The rated normal current of the circuit breaker is an RMS value of the current.

USES 

1.Circuit breakers are used in high voltages line, low voltage line, transformer.

2. Protect the electrical circuit.

3. Protect all types of electrical equipment using in the circuit.

This topic is related to the introduction of circuit breakers which is the most common part of an electrical and electrical circuit, We learn and discuss this topic easily and deeply knowledge about circuit breakers their types, and operation their principle of the circuit breaker.

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WHAT IS ELECTRIC CLOTH PRESS?TYPE OF ELECTRIC IRON:?

WHAT IS AN ELECTRIC CLOTH PRESS? TYPE OF ELECTRIC IRON?

Today I am going to tell you about electric iron. It is used in our daily life. Today we will tell its Construction and its importance.

Automatic Electric Iron - 

Automatic electric iron weighs less than normal iron. Its wattage is 1000 watts. It is fitted with a thermostat. It has a switch. By which it gets heated to the specified temperature and closes on its own. It turns on automatically when something cools down.

Steam Electric Iron -

 This press is used to give water or steam to clothes. The remaining parts in this press are like an automatic press. There are small holes in the sole plate from which the steam comes out and after spraying it on the cloth, it softens the water and presses the cloth.

Electric Iron Electric Press is the most commonly used electric appliance in our homes and businesses. The presses commonly used in homes range from 350 watts to 450 watts.

Their weight varies from 1 kg to 1.5 kg.

Electric Press Body

1. Sole plate

2. Heating element

3. Pressure plate

4. Cover

5. Handle

6. Socket

7. Heel

8. Plug, plug-top and mains lead (Plug, plug-top and mains lead)

Sole plate - 

This plate is made of mild steel. Its shape is triangular. Its length is 20 cm to 30 cm, width 12 cm to 18 cm and thickness is 10 cm to 15 cm. All the ingredients are grated on this surface.

Heating element - 

This is a triangular piece of asbestos. A wire of nichrome is wrapped on this flat mica piece. Two copper alloy blades are attached to the ends of this fiber. Its watts are 350 W, 450 W, 600 W and 750 W. These fibers are set at the terminal between two triangular plates of asbestos. And it is placed on the top of the sole plate.

Pressure plate - 

Cast iron or mild steel plate is tightened by placing a sheet of asbestos on top of the thermal fiber. There are two holes on the pressure plate which is bolted tight to the soul plate.

Cover - 

This is an iron cover. Which is mounted on the sole plate. Which protects the presser from the heat emanating from the electric current and the heat fibers.

Handle - 

This is a bad conductor of heat. The handle is made of wood, bakelite or plastic.

Which is tightened with a bolt on the cover.

Socket -

In this, the fibers of the fibers are kept. we call a socket.

Heel -

Hot presses cannot be placed on wood, flooring or clothes. Heels are fitted to keep it at bay.

Plug, plug-top and mains lead - 

These are used to power the press.

   

आज में आपको इलेक्ट्रिक इस्त्री के बारे में बताने जा रहा हूँ | इसका उपयोग  हमारे दैनिक जीवन में  किया जाता है | आज हम इसकी बनवाट और इसके महत्व को बतायगे | 

इलेक्ट्रिक आयरन के प्रकार 

1. आटोमेटिक इलेक्ट्रिक आयरन (Automatic Electric Iron)

2. स्टीम इलेक्ट्रिक आयरन (Steam Electric Iron)

आटोमेटिक इलेक्ट्रिक आयरन (Automatic Electric Iron)-

आटोमेटिक  इलेक्ट्रिक आयरन का वजन सामान्य  आयरन से कम होता है |इसका वाटेज  1000 वाट होता है | इसमें थर्मोस्टेट लगया जाता है | इसमें एक स्विच होता हैं | जिससे ये निर्धारित तापमान तक गर्म होकर अपने आप ही बंद हो जाता है | कुछ ठंडा होने पर अपने आप ही पुनः ऑन हो जाता है | 

स्टीम इलेक्ट्रिक आयरन (Steam Electric Iron)-

इस प्रेस का प्रयोग कपडे को पानी अथवा भाप देने के लिए किया जाता है | इस प्रेस में बाकि भाग आटोमेटिक प्रेस की तरह ही होते है | सोल प्लेट में छोटे छोटे छिद्र होते जिन से भाप निकल कर कपड़ो पर छिड़के हुए पानी के साथ मिलकर नर्म कर कपड़ो को प्रेस कर देता है | 

                                         इलेक्ट्रिक आयरन इलेक्ट्रिक प्रेस हमारे घरो और व्यवसाय में सर्वाधिक उपयोग में लायी जाने वाली इलेक्ट्रिक उपकरण है | सामान्यतः घरों में उपयोग में लिए जाने वाली प्रेस ३५० वाट  से ७५० वाट तक क्षमता होती है | 

इनका वजन १ किलोग्राम से लेकर १.५  किलोग्राम तक होता है | 

इलेक्ट्रिक प्रेस के मुख्य भाग 

1. सोल प्लेट (Sole plate)

2. ऊष्मक तन्तु  (Heating element)

3. प्रेशर प्लेट (Pressure plate)

4 .कवर (Cover)

5. हैंडल (Handle)

6. सॉकेट (Socket)

7. हील (Heel)

8. प्लग ,प्लग-टॉप तथा मैन्स लीड (Plug,Plug-top and mains lead)

सोल प्लेट (Sole plate)-

यह प्लेट माइल्ड स्टील की बनी होती है | इसका आकार त्रिभुजाकार होता है | इसकी लम्बाई 20  सेन्टीमीटर से 30  सेन्टीमीटर ,चौड़ाई 12 सेन्टीमीटर से 18  सेन्टीमीटर  तथा मोटाई 10 सेन्टीमीटर  से 15  तक  सेन्टीमीटर होती है| इस सतह पर सभी अवयव कसे हुए होते है | 

ऊष्मक तन्तु  (Heating element)-

यह अभ्रक का त्रिभुजाकार टुकड़ा होता है | इस चपटे अभ्रक के टुकड़े पर नाइक्रोम के तार को लपटा जाता है | इस तन्तु के सिरों पर तांबे की दो सयोंजक ब्लेड लगायी जाती है | इसका वाट 350 W ,450 W ,600 W तथा 750 W होता है | इन तंतुओं  को अभ्रक की दो  त्रिभुजाकार प्लेट के बीच टर्मिनल पर सेट कर दिया जाता है | और इसको सोले प्लेट के ऊपर रख दिया जाता है | 

प्रेशर प्लेट (Pressure plate)-

ऊष्मक तन्तु के ऊपर ऐस्बेस्टस की शीट को रख कर कास्ट आयरन या माइल्ड स्टील की प्लेट को कसा जाता हैं | प्रेशर प्लेट पर दो छिद्र होते है जिसे बोल्ट से सोल प्लेट पर कस दिया जाता है | 

कवर (Cover)-

यह एक लोहे से बना आवरण होता है | जो सोल प्लेट के ऊपर लगा होता हैं | जो प्रेस करने वाले व्यक्ति  को इलेक्ट्रिक करंट और ऊष्मक तन्तु से निकलने वाली उष्मा से बचाता हैं | 

हैंडल (Handle)-

यह ऊष्मा का कुचालक  होता है | हैंडल लकड़ी ,बैकेलाइट या प्लास्टक का बना होता है | 

जोकि कवर पर बोल्ट से कसा होता है| 

सॉकेट (Socket)-

इस में तन्तु के सयोंजक पत्तियों को रखा जाता हैं | जिसे हम सॉकेट कहते हैं | 

हील (Heel)-

गर्म  प्रेस को लकड़ी ,फर्श  या कपड़ो पर नहीं रखा जा सकता हैं | इसे खाड़ी अवस्था में रखने ने के लिए हील को लगया जाता हैं | 

प्लग ,प्लग-टॉप तथा मैन्स लीड (Plug,Plug-top and mains lead)-

इनका उपयोग प्रेस को पावर  किया जाता है | 

 

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What is two port network ?Introduction the two port network ?

What is two port network ?

 Introduction the two port network

 A number of impedance are Connected to the system elements and consist the set of elements which are connected in group or set of elements they consist circuits are performed specific function. It is called a network function. Which are the combined of many elements of electrical components like resistance, capacitor or inductor etc.

Network elements

  In a network theory .A network elements components of circuit having different characteristics.

1.       Linear or non linear network  element characteristics

2.      Active or passive network  element characteristics

3.      Unilateral or bilateral network  element characteristics

Linear or non linear network element characteristics- 

The characteristic simply shows with voltage and current. The linear elements show a linear characteristic or linear elements are resistance ,capacitor or inductor  their resistance , capacitance or inductance  are not change with changing apply voltage or current.

A non linear element is the current passing through without changing linearly. When the apply voltage change linearly in the particular frequency. That called a non linear element like semiconductor devices.

Active or passive network element characteristics-

if a circuit element has the ability to increase the energy level and signal pass through the circuit it is called a active element. ex. vacuum tube, semiconductor devices are active elements.

A elements are (resistance ,capacitor or inductor ) passive elements. Because this elements are not boosting the energy level or signal.

Unilateral or bilateral network  element characteristics-

If the magnitude of the current passing through an elements is affected due to change in the polarity of the applied voltage .It may be offer varying impedance with variation in flow of current. Ex diodes ,transistor are unilateral elements.

If a current magnitude remain changed in applied emf s polarity is called a bilateral element. It may be offer varying impedance with variation in flow of irrespective current. Ex resistance ,capacitor or inductor are bilateral element.

Classification of network

1.      Linear circuit network

2.      Non linear circuit network

3.      Active circuit network

4.      Passive circuit network

5.      Unilateral circuit network

6.       Bilateral circuit network

7.      Lumped circuit network

8.      Distributed circuit network

9.      Recurrent or cascaded circuit network and Non recurrent circuit network

Linear circuit network-

It is the circuit whose parameter remain constant change with voltage or current. Ex resistor, capacitor or inductor. A linear circuit obeys Ohm s law current is directly proportional to voltage.

Non linear circuit network -

It is the circuit whose parameter change with voltage or current.Ex semiconductors.non linear circuit not follows Ohm s law.

Active circuit network-

It is network , Which is contain one or more than one source of EMF. An active elements like a battery or transistor.

Passive circuit network-

It is network, Which is not contain any source of EMF is called a passive element. It does not contain any source of energy.

Unilateral circuit network-

When the current direction is changed the circuit properties or characteristic also may be a change is called a Unilateral circuit.

Bilateral circuit network-

When the current direction is changed the circuit properties or characteristic not may be a change is called a Bilateral circuit.This type of element are mostly made of high conductivity.

Lumped circuit network-

Physically separate network elements like resistance, capacitor  and Inductor are known as lumped element.

Distributed circuit network-

A element whose Physically not separate network elements like transmission line are known as Distributed element.

Recurrent or cascaded circuit network and Non recurrent circuit-

When a large circuit consists of similar networks connected one after another , is called a recurrent circuit. A single network is called a non-recurrent circuit.

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Graph theory of network elements

Introduction of Graph theory 

Today we study a circuit graph theory which is the part of circuit theory, In this theory we learn how to implement the basic concept of graph theory in circuit design.

The graph theory is simplify a circuit, In all circuit element (Resistance, capacitor or inductor ) are reduce by node ,dots and lines. The elements are represented One node to another node. The nodes are connected to line between two nodes. The all nodes are intersection of two or more branches and representing the network element of lines, voltage and current sources by their internal impedance. The line connected two or more points are called a node. And drawn lines are called branch. Number of branches is equal to the number of nodes. Node are denoted by small letters ( a, b, c ......) and Number (1, 2 ,3....) denoted to elements or branch.

Branch- 

A line which is connected to two and more than nodes this line are called branch. It is not shown which type of element is connected to the circuit. Only represent indirect or direct/oriented graph network path. In graph network min two branches and max two or more than branches.

Node- 

A point which is defined a first point or end point of element this point are called node. Nodes are isolated elements or branches. There are exactly two paths between ant pair of nodes in a circuit. Degree of a node is the number of branches incident to it.

Tree- 

It is connected to open set of branches. Tree is defined and distinct branch set in the close loop graph. Open set branches are interconnected to each other in this condition graph cannot be any close loop.

Tree branch or twig- 

Any branch of tree (n-1) is called a twig.

Chord - 

It is simplify the graph. It cannot be belong to any particular tree also called co-tree. Its linked to tree.

Path – 

An ordered sequence of branches way to one node to another node is called path in a graph.  

Properties of tree in a graph network theory

1.      Tree consists of nodes in a tree one path between two nodes.

2.      At least one tree is connected every graph.

3.      If the graph has N number of node, the tree will have (N-1) branches.

4.      Tree is open set of graph no closed path in the tree.

5.      Graph is depending on the number of nodes and branches.

Relation between Twigs and links

 The number of twigs on a tree is always one less than the no. of nodes (N-1).

N-No of Nodes

(N-1)- No of twigs

L= It represents the total no. of links.

B=Total no of branches

L=B-(N-1)

L=B-N+1

Circuit or loop-

In a graph tree contains a closed path this resultant is called loop or circuit.

Cut - set- 

The cut-set is separates part of elements or branches and dividing part are connected with dashed line. It separates the nodes into two groups. Cut sets containing only one twig are independent. T he number of cut sets is equal to the number of twigs.

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What is Transformer? Different Types of Transformer

What is Transformer

Principle- 

A transformer works on the electromagnetic induction law or mutual induction law.The primary or secondary coils are coupled with magnetic field.

Construction of transformer-

The transformer is a static device which can be transfer power one palace to another palace (one circuit to another circuit) it means the current and voltage  through by medium of magnetic field without changing frequency. The main supply connected to input terminal that called a primary winding and output terminal connected to a load that called a secondary winding.the transformer is an electromagnetic energy conversion device. The primary winding and secondary winding are not connected electrically But they are coupled by magnetic field. The magnetic field transfer the high voltage to low voltage and low to high voltages as per direction same voltage from primary to secondary winding.The transformer magnetic core is made of cold rolled grain oriented sheet steel layers.This layers are laminated thin silicon-steel. The layers wound by copper winding that winding are called a primary and secondary Winding.
Working- Transformer core is working on magnetic flux.In a diagram shown the primary or secondary winding have a Np or Ns turns in transformer.Coil are connected with magnetic field.Primary current or voltage are supply terminals of transformer.Secondary current or voltage are load side of terminal.In core magnetic flux will be produce same current or voltage secondary winding respect with primary winding.but such case like step up or step down transformer both side current or voltage is depended on theirs turns. 

Types of Transformer: 

1.Step up transformer

2.Step down transformer

According to Construction of transformer

3. Core type

4. Shell type

Step up transformer-

If the secondary winding turns has more than the primary winding.The secondary voltage more than the primary voltage So the input voltage is lower than the output voltage is called a step up transformer. In a step up transformer winding increase in secondary winding the output voltage is more than input voltage.

Step down transformer-

If the secondary winding turns has less than the primary winding.The secondary voltage less than the primary voltage So the input voltage is higher than the output voltage is called a step down transformer. In a step up transformer winding decrease in secondary winding the output voltage is less than input voltage.

According to Construction of transformer

The transformer works on the principle of electromagnetic induction between two coils.Transformer is generally construct two type
1. Core type

2. Shell type

                 The transformer is very simple in construction and consists of magnetic circuit linking with two winding primary and secondary winding. Transformer assembled core and winding. The magnetic core is a stack of thin silicon steel lamination about 0.35 mm to 0.5 mm for a 50 Hz transformer.In order  to reduce the eddy current  losses , these lamination are insulated from by thin layer of varnish. The magnetic core made from cold rolled gain oriented sheet steel material is magnetized in the rolling direction has low core loss and high permeability.

Core type-

Core type has two legged core. In core type transformer the flux has a single path around the leg or yokes , the flux in the central limb divides equally and returns through the outer two legs.This type of transformer is used high voltage and high power level. The concentric coils are used in transformer.

Shell type-

Shell type has three legged core. In winding are wound over the central limb and are interleaved or sandwich. This type of transformer is used low voltage and low power level. Interleaved or sandwich coils are used in transformer.

                                       

During the transformer construction, first the primary and secondary wound a winding and lamination the open coils.The lamination are tightened by clamps and bolts.Low power transformer are air cooled  based and high power transformer are oil cooled (coolant). For power frequency range 25 to 400 Hz and radio frequency range 20 to 20000 Hz. The core is made of powdered ferromagnetic alloy.The various assumption are as follows.

1. Negligible resistance of winding.

2. The hysteresis and eddy current losses are negligible.

3. Permeability of core is a constant.

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Difference between Synchronous and Induction Motor

Synchronous Motor:

A Synchronous motor same relationship to an alternator as a Dc motor If the alternator supplying the AC power to run the motor to doing mechanical work .If the mechanical work apply on rotating alternator. It removed remaining DC power and supply the AC power to the armature terminal the torque will be developed and alternator running continuetly . We find the speed of motor by the AC supply frequency and number of poles on the synchronous machine. 

The poly-phase synchronous motor same as a alternator. The essential parts of a three phase synchronous motor are:

1. Lamination stator core with three phase armature winding

2. Rotating field structure complete with damper winding and slip rings.

3. Brushes and brush holder.

4. Two end shields to house the bearing that support the rotate shaft. 

Stator core and winding most commonly as three- phase alternator The leads from the stator winding terminate in terminal box. The salient field poles connected to give alternate polarity. The number of rotor field poles same as stator field poles. The field circuit leads two slip rings mounted on the shaft and carbon brushes mounted in brush holders make connected with a two slip ring.

Induction Motor:

The induction motor is the used as a AC motor. Induction motor low in cost, simple extremely rugged construction, high reliability, high efficiency, reasonably good power factor low maintenance cost and simple starting arrangements. It differs from other types of electric motors in that there is no electrical connection from the rotor ending to any source of supply. The necessary current and voltage in the rotor circuit are produced by induction from the stator winding. This is the reason that it is called the induction motor.

The induction motor consists of two parts 

1. Stationary part known as stator

2.The revolving part, known as the rotor. Induction motor are depending on three type of rotor. 

1.Squirrel cage rotor 

2.Wound rotor or slip ring 

3.Double squirrel cage rotor. All induction motor working on same principle. 

Comparison Between Synchronous and induction motors:

S. no	INDUCTION MOTOR	SYNCHROUNOUS MOTOR
1	It has got no self starting torque and some external means is required for its starting.	No special means is required for starting But It has got self starting torque.
2	Average speed is constant and independent on load.	Its speed falls with the increase in load and always less than synchronous motor.
3	It can be operated under a wide range of power factor depend on lagging or leading.	It operates only lagging power factor not on depend on leading power factor .which becomes poor at lights loads.
4	It required DC excitation So it is a Doubly excited machine.	It required no DC excitation So it is a singly excited machine

This is all about difference between induction motor and synchrounous motor. 

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