MEO Class 4 Operate – 5 Electrical Oral Questions and Solutions

MEO Class 4 Operate 5 (EECEOL ) Electrical Questions With Solutions

What’s an Induction Motor ?

An induction motor is an Asynchronous motor by which Electrical Present required to Rotor to Produce Torque, Which is obtained by Faraday’s Lay of Electromagnetic Induction.

Induction Motor Working Precept ?

An Induction Motor Works on the precept of Faraday’s Legislation of Electromagnetic Induction.

Faraday’ Legislation of Electromagnetic Induction has Two legal guidelines.

Faraday’ First Legislation

It states that, at any time when there’s a change within the magnetic subject linked with a circuit, an induced e.m.f ( electromagnetic drive ) is produced in it. Or, The electromagnetic induction is the phenomenon by which the electromotive drive induces throughout {the electrical} conductor when it’s positioned in a rotating magnetic subject.

Faraday’ Second regulation

It states that, the magnitude of induced e.m.f is the same as the speed of change of the magnetic flux linked with a closed circuit.

E.M.F = Charge of Change of Magnetic Flux.

State Working of An Induction Motor

Sorts of an Induction Motor

1. Single Section motor

  • Cut up section
  • Capacitor begin
  • Capacitor begin capacitor run
  • Shaded pole


  • Slip ring
  • Squirrel cage induction motor

Sorts of Motor

1. DC Motors

  1. DC shunt motor
  2. DC Sequence motor
  3. Compound motor
  4. Everlasting magnet motor

2. AC Motors

  1. Induction Motor
  2. Synchronous Motor

3. Different Motors

  • Common Motor
  • Brushless motor
  • Stepper
  • Servo motor

The right way to keep correct temperature within the Batter room

By correct air flow

Battery Room heating prevention

  • Swap ought to be outdoors.
  • Paint used ought to be Acid Proof.
  • Intrinsic protected gear
  • Intrinsic protected lighting

And through upkeep

  • Used Intrinsic protected torch
  • Insulated spanner and jug

Lenz’s Legislation

It states that, the course of the electrical present induced in a conductor by a altering magnetic subject is such that the magnetic subject created by the induced present opposes modifications within the preliminary magnetic subject. Or, An induced present at all times stream within the Path such that it opposes the magnetic subject which produce it.

All motor working precept utilized in Engine Room ?

1. An Induction Motor :- Faraday’Legislation of Electromagnetic Induction

2. Synchronous Motor :- It really works on the precept of Magnetic Locking between Rotating Magnetic Discipline ( this subject produced by 3- section provide to the stator ) and Static magnetic subject ( this subject produced by D.C provide to the rotor ).

3. DC Motor :- It really works on the Precept of Lorentz’ s Legislation.

Lorentz’s Legislation

It states that, at any time when a present carrying conductor positioned in a magnetic subject, it expertise a drive.

Brushless Alternator

It’s an alternator, which is used to generate mechanical vitality to Electrical Power through the use of Two Rotor fitted finish to finish on identical shaft and switch electrical energy with out brushes and slip rings.

Or, It’s an alternator, which don’t makes use of brushes and slip rings and include two alternator, important exciter and small exciter alternator by which excitation is completed by small Exciter Alternator fitted on the identical shaft of important alternator with the assistance of the Bridge Rectifier.

Benefits of Brushless Alternator is Much less Value and Upkeep is much less because of absence of brush and slip rings.

Transformer Loss

It’s a Loss within the Transformer in type of Warmth produced by {the electrical} present flowing within the coils and the alternating magnetic subject ( Flux ) within the core.

Two kinds of losses are :-

1. Iron/Core Loss

2. Copper Loss

1. Iron / Core Loss

It’s a Loss within the type of warmth because of Alternating magnetic flux within the core.

It’s a fastened loss. It solely depends upon the Voltages.

a. ) Hysteresis Loss :- It’s a Loss within the core of transformer because of magnetisation or demagnatisation of the Core.

It’s Lowered through the use of core made up of Silicon Metal.

b. ) Eddy Loss :- It’s a Loss within the core because of stream of Eddy present. Or,

It’s a Loss within the core because of stream of present produced by regulation of Electromagnetic Induction of magnetic flux because of enter provide to Transformer..

This present has no helpful work and produce a loss I^2 R.

2. Copper Loss

It’s a loss happen because of Ohmic Resistance of Winding of Transformer.

Copper Loss :- I^2 R.

It’s a variable loss and depend upon Present.

HRC Fuse

It means excessive rupturing capability fuse

It’s a fuse by which, fuse wire or component carry Brief Circuit Heavy present for a Identified Interval of Time. Throughout this time interval, if the fault will get eliminated then it doesn’t Blow off.

Battery Room Upkeep

Hyperlink :-

Underneath Voltage Safety

Underneath Voltage Safety is a security gadget fitted on all generator circuit breaker and feeder circuit breaker. It’s important perform is to journey the breaker when a extreme voltage drop happens throughout the the circuit breaker.

Underneath Voltage Safety on a circuit breaker,it additionally prevents from circuit being closed when the generator voltage may be very low or absent.

It might be magnetic or digital which offer back-up safety to quick circuit safety.

Be aware :- Underneath voltage safety is also called beneath voltage relay and beneath Voltage journey.

Sorts of Starter used on Ship With Instance ( on which motor used ?

1. D.O.L Starter :- Hydrophore Pump Motor, Boiler Feed Pump. Small motor utilized in Engine Room having Energy Much less tha 7.5 KW or 10 Horsepower.

2. Star Delta Starter :- Most important Sea Water Pump Motor, Air Compressor Motor, Fireplace and GS Pump Motor, Most important Fireplace Pump.

3. Transformer Starter :- Ballast Pump Motor.

4. Delicate Starter :- Conveyor Belt

What Multimeter Measure

  1. Continuity Take a look at
  2. Resistance
  3. Present
  4. Voltage
  5. Capacitance
  6. Inductance

Electrical measuring devices

  1. Clamp meter
  2. Voltmeter
  3. Ammeter
  4. Megger
  5. Multimeter
  6. Temperature gun

Armature response and how one can scale back it ?

It’s the impact on the principle subject Flux because of flux generated by present within the armature winding.

The right way to dampen

  1. Pole stacking
  2. Through the use of laminated pole
  3. Through the use of interpole between important subject.

Motor Safety System

  1. Underneath Voltage Relay
  2. Over present and Single section relay
  3. Brief Circuit Relay
  4. Temperature sensor for Motor Insulation

Fuse and Circuit breaker cone beneath over over present and quick circuit fault.

What’s Earth fault ?

When any one of many section touched with earthed, often called Earth fault.

A Earth fault is a fault because of break within the insulation, and conductor touched the hullor an earthed metallic enclosure.

Earth fault in Motor

Earth fault in Motor when stay wire of any section get earthed.

Cause of the Earth fault

  1. Failure of Insulator
  2. Free wire Connections of wire

The right way to detect an Earth fault in Motor

Verify IR Take a look at of Motor, Section to Earth.

Insulation Resistance worth between section to earth = Infinite

The right way to examine Continuity Take a look at of Fuse

Main Causes of the Electrical Fireplace on Board

  1. Brief Circuit
  2. Overheating
  3. Spreading of a strong or liquid hearth.

MSB Fireplace

  1. Overload of the conductor and will overheat, leading to a hearth.
  2. Free Connection of Nut trigger Spark.
  3. Insulation failure of wire and touched with different wire and quick circuited.
  4. Area heater isn’t working because of technology of moisture get quick circuit.
  5. Arc Chute isn’t working correctly.

Useless Man Alarm

It’s an alarm, which is used for monitoring the presence of Engineer within the Engine Room on UMS Ship.

Location of Useless Man Alarm

  1. ECR
  2. Engine Room lodging Station 1
  3. Engine Room lodging Station 2

Engineer goes on the Engine Room at evening for watch then he ought to should activate the Useless Man Alarm. It’s as a result of, he can be alone within the engine room and if he will get injured then there isn’t a one to attend the Alarm. Alarm will ring unattended. One other alarm is fitted within the chief Engineer cabin. He recue the watch retaining engineer.

Use of house heater in alternator and motor

Alternator and motor usages house heater to stop moisture condensation in the course of the time, motor isn’t operating.

Delicate Starter

It’s a starter which restrict the beginning present by supplying a regularly growing a.c voltage throughout begin up.

To restrict beginning present, a smooth starter will slowly and regularly growing voltage utilized to the motor.

In every section, a parallel reverse SCR is used. SCR also called Thyristors.

Benefits of sentimental starter w.r.t to ther starter

It permits clean operations of energy as an alternative of sudden energy provide like different starter.

What’s going to you do, if stage within the battery lower.

We put distilled water in it.

Be aware :- We don’t use mineral water, as a result of it comprises some impurity which harm the plate of battery.

Operating Motor Upkeep

  1. Sound / Noise
  2. Vibrations
  3. Heating by touching ( Temperature 🌡️)
  4. Basis bolt
  5. Fan
  6. Misalignment/couplings

Causes for Motor Overheating

  • Air flow holes blocked
  • Motor operating constantly
  • A poor surrounding setting
  • Improper voltage provide
  • Dangerous or jammed motor fan
  • Noise to electrical motor additionally causes of Overheating.

Shore Provide Specs

Residual Magnetism

It’s a property of fabric by which some quantity of excitation stay within the conductor after elimination of magnets. Or, Residual magnetism is outlined as the quantity of magnetization left behind after eradicating the exterior magnetic subject from the circuit.

Steering gear Security


Distinction between slip ring and Commutator

Slip rings :-

1. It’s a Electrical gadget, which is used for Transmission of Electrical Energy and sign from stationary to rotary components with out altering the polarity of present.

2. It’s Steady

3. Instance :- AC Motors


1. It’s a electrical gadget that that Electrical Energy or keep electrical continuity between stationary and rotary components by altering the polarity ( or periodically reverse the Path of at present between rotar and exterior circuit ).

2. It’s segmented

3. DC Motor

Bodily Distinction between Commutator and slip rings is slip rings is steady ring whereas Commutator is segmented.

Eddy Present

It’s a loop of electrical present induced inside the conductor by altering magnetic subject within the conductor in line with Faraday’s of Electromagnetic Induction.

Eddy present loss is the loss within the type of warmth happen because of stream of Eddy present.

Eddy Loss might be diminished by

  1. Laminated core
  2. Through the use of skinny sheet of core.

Sorts of Management System

Open Loop System

The Management System by which the required output doesn’t depend upon the Enter or Controlling Actions.

Instance :- Gentle, Distant, Site visitors Gentle.

Shut Loop System

The Management System by which output depends upon the enter or Controlling Actions and many others.

Instance :- AVR in alternator, Refrigeration System and many others.

Air Hole in Motor or Alternator

It’s a hole between shifting Rotor and the Stator core.

Or, It refers to a plastic hole within the motor and alternator which separates the shifting Rotor and the Stator core.

Enhance Air hole

  1. Magnetic flux hyperlink with rotor and stator lower trigger lower in torque in motor and Generated voltage in alternator.
  2. Manetising present Enhance.
  3. Magnetising reluctance lower.
  4. Permeability lower.

Lower air hole

  1. Bodily Injury of Stator core and the rotor.
  2. Not correct Cooling
  3. Mud Will accumulate in between hole.
  4. AIr hole lower trigger magnetic flux improve and alter of getting overheat of winding and get harm.

Air hole :- 1.5 Cms to 2.0 Cms.

Clamp Meter and it’s working precept

It’s an Electrical Measuring System, which is used for measureing the Electrical present of Present carrying conductor with out having make bodily Contact.

Working precept :- It really works on the precept of Faraday’s regulation of electromagnetic Induction to be able to make no-contact AC Present measurements.

Extinguisher used for Electrical hearth.

  1. Dry Powder
  2. CO2

Parameter examine befor paralleling of generator

  1. Frequency
  2. Voltage and
  3. Section


It’s a unit of electrical cost, having Dimenstions equal to electrical present multiplied by time equal to the cost stream by means of a gentle present of 1 ampere in a single hour.

Battery Capability

Battery Capability is the measure of quantity of cost obtainable in ampere-hours (AH ).

The battery capability represents the utmost quantity of vitality that may be extracted from the battery beneath sure specified circumstances.

How battery capability is measured ?

The capability of battery is measured by discharging at a relentless present untill it reaches terminal voltage (often it’s 1.75 volts ). It’s often achieved at fixed temperature of 25 diploma celcius.

The capability is calculated by multiplying the discharge present worth by the point required to achieve terminal voltage.

Present Transformer

It’s a gadget used to remodel excessive A.C to Low A.C.

Or, it’s a gadget that’s used fo transformation of present from the next worth of present right into a proportionate decrease present.

Present Transformer works within the precept of Faraday’s regulation of electromagnetic induction.

Supplies utilized in Present Transformer is Silicon Metal Core.

It’s utilized in Clamp meter.

Emergency Swap board Distribution

  • Emergency Bilge pump (440 V)
  • Sprinkler system (440 V)
  • One of many steering gears (440 V)
  • Navigation Tools (220 V)
  • Radio Communication (220 V)
  • Reworked and rectified provide to Battery techniques (220 V)
  • Transitional Emergency Energy Battery (Emergency lights for half-hour)
  • Low energy DC system Battery (Alarms and management system)

What are the gear which get provide from emergency generator ?

  • It’s referred to as emergency load
  • Emergency lightening to alley approach /boat deck / engine room.
  • Navigation system
  • Steering gear
  • Emergency hearth pump
  • Emergency air compressor
  • Battery charging
  • Fireplace detecting and alarming system
  • Radio equipments (Communication gear)
  • Daylight signaling lamp and ship’s whistle
  • Navigation Aids
  • Basic Alarm
  • Handbook hearth alarm
  • Watertight doorways

Sequential Beginning

It’s an Automated beginning of an Important Tools when energy is returned or backup after a complete energy failure.

Instance :- Tools begin akin to Gas Oil pump, Steering gear motor, Lube Oil Pump, Sea water Pump and many others.

Synchronous Motor and dealing precept

A synchronous motor is an AC Motor by which rotation of rotor or shaft is synchronised with frequency of Provide Present.

Or, an AC Motor which run with Synchronous Pace.

Be aware :- It’s not self began motor. It’s double excited motor run at fixed velocity.

Synchronous motor working precept :- It really works on the precept of magnetic locking.

Why synchronous motor isn’t self began motor.

Synchronous motor works on the precept of magnetic locking. There’s drive act between Rotating Magnetic Discipline and Static magnetic subject produced by DC provide in rotor. However, it doesn’t capable of rotate rotor because of inertia. So, it required exterior supply to rotate.

In some synchronous motor, Exterior supply is DC Motor and by offering a particular winding on the rotor poles, often called damper winding or squirrel cage winding

Distinction between Motor and Generator

Motor 1. It’s a gadget which converts electrical into mechanical vitality. Generator 1. It’s a machine which mechanical vitality into electrical vitality.

Motor 2. It consumes Electrical Power. Generator 2. It generates electrical vitality.

Motor 3. Mutual induction of magnetic subject answerable for rotation of rotor. Generator 3. Rotor rotates bt exterior supply.

Motor 4. Fleming’s Left hand rule used for locating the course of rotation of motor. Generator 4. Fleming’s Proper hand rule used for locating the course of induced present.

Distinction between DC generator and AC generator

DC generator

1. DC generator used for producing Direct present. 2. Commutator is used. 3. It’s used for generate much less voltage. DC cannot be generated at excessive voltages as a result of sparking begins on the Commutator at excessive voltage and trigger Commutator get broken.

AC generator

1. AC generator used for producing Alternating present. 2. Slip ring is used. 3. It’s used for top AC voltage.


It’s an digital gadget that maintains fixed voltage at output of generator beneath varrying load.

Or, It’s a suggestions management system that measures the output voltage of the generator, compares the output on the set level, and generates an error sign that’s used to regulate excitation of the generator.

Elements of AVR

  • Transformer
  • Rectifier
  • Zener diode
  • SCR
  • Exciter

AVR working precept

It really works on the precept of detection of error.

Be aware :- Error sign is used to regulate subject present by growing or lowering the present stream to am exciter stator.

Synchroscope working and dealing precept

It really works on the Precept of magnetic locking between static subject (Pole ) and rotating magnetic subject ( within the armature winding).

Working precept

Most important components :- 1. Motor poles and a pair of. Armature Winding

It consists of small motor with coils on two poles related throughout two section of the the incoming generator title R and Y.

Notes :- Static magnetic subject N and S poles Generated because of two section. If three section then generates rotating magnetic subject.

There’s Armature Winding, equipped from Purple and Yellow section from switchboard bus bar.

Armature Winding consists of two parallel coil in armature Winding. With one coil resistance and with one other coil Inductor is related.

Inductor is related parallel with resistance which delaying the present by 90° to present of resistance. It create section distinction and create rotating magnetic subject in armature Winding.

Polarity of Rotating Magnetic Discipline change alternatively in North and South. Rotating magnetic subject will react with the poles of motor and switch the rotor clockwise and anticlockwise.

Whether it is rotating in clockwise which means incoming generator has extra frequency that operating generator. Whether it is rotating in anticlockwise, means frequency of incoming generator is lower than operating generator.

Be aware :- Frequency of incoming generator improve or lower by the use of velocity adjuster of prime mover mover.

Three Lamp technique


What’s a Diode

A diode is a semiconductor that enables the stream of electrical energy in a single course solely and block the stream within the reverse instructions.

Be aware :- It’s thought to be one-way valves and they’re utilized in numerous circuits, often as a type of safety.

Instance :- Gentle emitting diode ( LED ), Rectifier Diode and photodiode.

Utility :-

  • Rectifying a voltage: turning AC into DC voltages.
  • isolating indicators from a provide
  • Controlling the dimensions of a sign
  • Mixing (multiplexing) indicators.

Use of diode in alternator

Diode is utilized in Alternator as a diode rectifier which convert A.C into DC in AVR.

Zener Diode

A zener diode is a diode which allows present not solely within the ahead instructions like a standard diode, but in addition within the reverse course if the voltage is bigger than the breakdown voltage often called zener knee voltage or zener voltage.

Instance :- In AVR, Intrinsically protected Tools

Functions :-

  • As a Voltage stabilizer for low-current functions
  • Generations of reference voltage ( Ex for an amplifier stage )
  • Switching functions
  • Clipper circuit and
  • surge suppressor

Silicon Managed Rectifier or Thyristors

Silicon :- Semiconductor Supplies. Rectifier:- Convert AC to DC. It management AC to DC

A SCR is a unidirectional semiconductor gadget made up of Silicon which is used to vary alternating present into direct present and on the identical time can management quantity of energy fed to the load.

Be aware :- Thus, SCR Combines the options of a rectifier and a transistor.

Utility of SCR

  • AC energy management (together with lights, motors and many others. )
  • AC energy switching ( as a swap )
  • Pulse management
  • Rectifier
  • Over voltage safety
  • Section management :- Management components in section angle triggered cintrollers
  • Pace management

Use of SCR in alternator

Silicon Managed Rectifier is utilized in AVR for Controlling the quantity of excitation present to keep up fixed voltage at output of generator.

Use of Rectifier

In motor , alternator and AVR


It’s a kind of semiconductor whose resistance range with change in Temperature (🌡️).

Utility :-

  • Fireplace alarms
  • Measure Motor winding temperature
  • Thermal relay
  • Digital Thermometer
  • Oven
  • Fridges

Sorts of Circuit breaker

On the premise of arc quenching medium

  • Air circuit breaker
  • Vaccum circuit breaker
  • Oil circuit breaker
  • SF6 circuit breaker

What’s CKT breaker

A circuit breaker is a electrical swap designed to guard {an electrical} circuit from harm brought on by extra present usually ensuing from overload or quick circuit.

It’s {an electrical} swap which is used for shut or open the circuit bin regular or defective circumstances.

Defective circumstances :- Overload,over present and quick circuit.

Capabilities :- It’s perform is to intrupt present stream after a fault is detected.

Be aware :- It may be operated manually or routinely.

Distinction between fuse and Circuit breaker


Sorts of motor utilized in Engine Room

Induction Motor

1. Single section :- Small pump, Drilling machine, Exhaust fan in toilet of cabin.

2. Three section :- Engine auxiliary pump, Blower fan, Most important Fireplace Pump, S.W pump

Synchronous motor

1. Single section :- Radar Gyrocompass

2. 3 section :- Bow thruster, Propulsion of ship

Windlass security


Lifeboat davit security


Places of libeboat davit and function

Lifeboat davit restrict swap is a security gadget which restrict the movement of davit when reaches the inboard place and make not possible for operator to make a mistake.

Or, it’s a security gadget which restrict the davit arms when reaches last stowed place.

Places :- It’s fitted on the bottom of davit arm.

Energy issue

It’s the ratio of True poper to Obvious energy. Or, It’s the cosine of angle between present and voltage.

Cos $ = Actual energy / Obvious energy

Significance of Energy issue

It’s measure of how a lot contribution of actual energy in obvious energy.

Cos$ = 0.8 , it means 80 p.c of obvious energy ( KVI ) is used as actual energy ( KW ) ( mechanical or warmth and lightweight ).

Low energy issue implies low energy consumption.

How will you enhance energy issue

  • Utilizing Capacitor financial institution in parallel
  • Section Advancer
  • Synchronous Condenser

Why capacitor is Utilized in parallel. It’s as a result of in parallel gear capacitance improve and this improve within the cost storage. Q = C eq × V

Cause for low energy issue

1. The primary purpose for low energy issue is Inductive load. Primarily Induction Motor. 90 p.c of load include induction machine. Such machine draw magnetising present to provide magnetic subject therefore work at low energy issue.

2. Variations in energy loading b:- When system is loaded evenly ,the voltage improve and the present drawn by machine additionally improve. Thus, leads to low energy issue.

3. Harmonic present

Disadvantages of low energy issue

  1. arge KVA rankings and dimension {of electrical} equipments.
  2. Poor voltage rules
  3. Massive Copper Loss
  4. Larger conductor dimension

Why DC provide is given for Excitation

After we provide DC as a exciter then it generates static magnetic subject within the type of North and South pole. If we provide AC then it generates rotating magnetic subject and it doesn’t create locking with with rotating magnetic subject of Stator winding.

Thus, it fails to synchronise with rotating magnetic subject of Stator winding and rotor is not going to transfer.

The right way to management velocity of induction motor

1. By altering the availability voltage of the motor I e star to delta however on this situation solely two velocity gradual or quick . Be aware :- If requested to vary velocity ( not management ) of induction motor then add this level.

2. By altering stator pole variety of the motor. It’s not potential to vary no. Of like every time so, we use

A. ) PAM ( Pulse Amplitude Modulation)

B .) A number of stator winding technique

3. By altering the frequency of energy Provide ( through the use of frequency converter MOSFET’S )

4. Including rheostat within the stator circuit.

The velocity controls of three section induction motor from rotor facet are additional categorized as:

1. Including exterior resistance on rotor facet.
2. Cascade management technique.
3. Injecting slip frequency emf into rotor facet.

Pace management of Synchronous motor

This velocity might be modified by altering the variety of poles or frequency of provide.

1. No of poles

2. By altering the frequency of Provide facet. It’s achieved through the use of rectifier and inverter in open or closed loop mode.

The right way to management velocity of DC motor

the voltage equation of a easy DC motor is

V = Eb + IaRa

V is the equipped voltage, Eb is the again EMF, Ia is the armature present, and Ra is the armature resistance.

We already know that

Eb = (PøNZ)/60A.

P – variety of poles,

A – fixed

Z – variety of conductors

N- the velocity of the motor

Substituting the worth of Eb within the voltage equation, we get

V = ((PøNZ)/60A) + IaRa

Or, V – IaRa = (PøNZ)/60A

i.e., N = (PZ/60A) (V – IaRa)/ ø

The above equation can be written as:

This suggests three issues:

2. The velocity of the motor is straight proportional to produce voltage.
2. The velocity of the motor is inversely proportional to the armature voltage drop.
3. Pace of the motor is inversely proportional to the flux as a result of subject findings
Thus, the velocity of a DC motor might be managed in 3 ways:

1. By various the availability voltage
2. By various the flux, and 3. by various the present by means of the sector winding
4. By various the armature voltage, and by various the armature resistance

Sorts of load

Three fundamental kinds of masses exist in circuits: capacitive masses, inductive masses and resistive masses.

1. Resistive load

Load which consumes solely lively energy is named as resistive load. Or, The resistive load is a load which obstructs the stream {of electrical} vitality within the circuit and converts it into thermal vitality, because of which the vitality dropout happens within the circuit.

Instance :- lamp and the heater

Be aware :- The resistive masses take energy in such a approach in order that the present and the voltage wave stay in the identical section. Thus the ability issue of the resistive load stays in unity.

2. Capacitive load

Capacitive masses embrace vitality saved in supplies and gadgets, akin to capacitors, and trigger modifications in voltage to lag behind modifications in present.

Instance :- Capacitor, Capacitor financial institution, buried cable , capacitor in fan, Generator AVR, 3 section induction motor

Notes :- 1. Voltage lags 90° from voltage. 2. Present leads 90° ahead the voltage.

3. Inductive load

It’s a load which convert electrical vitality into magnetic subject.

Instance :- motors, transformers and chokes, Vaccum cleaner, washer and many others.

Notes :- The present wave of the inductive load is lagging behind the voltage wave, and the ability issue of the inductive load can be lagging.

1. Voltage leads 90° by present. 2. Present lags 90° behind the voltage.

Generator producing no Voltage

  1. Lack of Residual Magnetism
  2. Failure re of AVR
  3. Failure of Excitation elements.

Generator producing much less voltage and Rectification

1. Load utilized to Generator exceeds the capability , will trigger machine decelerate and drop in frequency and voltage.

Treatment :- Run one other generator in parallel.

2. AVR Voltage achieve set too low to answer load being utilized.

Treatment :- Enhance voltage achieve set.

3. If AVR suggestions is from generator bus bar voltage terminal and voltage dip too far, all excitation may very well be misplaced and usually lead to beneath voltage.

Treatment :- AVR suggestions to be shut the generator.

4. Pace management achieve (Pace droop ) set too low.

Treatment :- Enhance velocity droop set.

5. Gas injector downside, governor downside, Air filter clogged, defective air coolers and many others.

Treatment :- They have to be rectified.

Use of Capacitor

  • Use to cut back voltage pulsation
  • Used for storage of vitality ( Energy financial institution )
  • Motor starter [ Use of capacitor in motor (single phase motor ) to create a poly phase ( varying magnetic field ) from a single phase power supply
  • Capacitor used in fan
  • Power factor correction

Use of diode, zener diode in alternator

Use of Diode :- Diode us used a bridge rectifier ( AC to DC ) in alternator.

Use of zener diode :- Zener diode is used as a generation of reference voltage. So, to produce error supply for Excitation and as voltage stabilizer in AVR.

Proximity Switch

It is a sensor that is used to detect the movement or presence of an objects without making physical contact with the object and convert into an electrical signal.

Advantages :- It is no contact sensor, and cause no damage to object.

Working principle:- It works on the principle of Faraday’s law of electromagnetic induction.

Applications :- It is used for sensing the RPM of main engine.

Inductive proximity switch Working :-

It has electromagnet coil in which supply given is from 24 V DC Source and another coil when magnetic flux changes due to metal sensing on flywheel, current is induced in secondary coil.

Magnetic pick up sensor is same as proximity switch but rhe only difference is , in place of electromagnetic coil there is a permanent magnet

Main switchboard safeties

  • Fuse,relay, circuit breaker
  • Under voltage relay
  • Reverse power trip
  • Preferential trip
  • Over current trip
  • Short circuit trip
  • Earth fault indicator
  • Arc Chute
  • Ebonite rod ( to remove static charge )
  • Dead front type Switch board :- It is a safety wherein you can not open the panel untill the power of that panel is switched off.

General safeties

  • Insulated hand gloves
  • Dry boiler suit
  • Shoes without metallic part
  • Rubber pad in front of the switchboard
  • 0.6 m gap behind switchboard
  • Panel doors to be earthed
  • Intelocked handles for opening door
  • No water, oil, or steam pipeline in its vicinity.

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