Why do some countries have 220V supply while some have 110V and some even have both ?

lif3_h4cK3r

• Jan 13th, 2012

Hello Friend,

The transmission of voltage purely depends on the laws of the country itself.
As Mr. V. N. Shekhar said, it depends on country and there is no technical reason for this adopted system.

Thanks.

Pasupulati. V. N. Sekhar

• Jan 9th, 2012

According to there standard of electrical transmission different sets of voltage and frequencies are chosen. In case of India we choose 220V and 50HZ as our voltage and frequency levels. Where as in some other countries they choose it as 110V and 60HZ

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which is bigger in size AC or DC, of same rating?
As I think DC is right answer but HOW? Explain?

Pasupulati. V. N. Sekhar

• Jan 17th, 2012

The main difference in the size come because of the set up that is present in the DC machines i.e., in order to tap DC voltage generated we require the set up such as Commutator and brush arrangement ...

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How choke coil and starter gives high voltage(1200v) across tube light to ionise gases in starting while after starting it limits voltage?

tharunp

• Jan 17th, 2012

After supplying 220v, the inductor will be charged. After certain time constant that inductor becomes open circuited. when inductor while charging, suddenly becomes open circuited means it develops hi...

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Why OC test is conducted on low voltage side?

A.santosh

• Jan 27th, 2012

If want to conduct OC test on HV side we need more turns of auto-transformer, as an engineers we should have to decrease the cost required for the test, so normally OC test is conducted on LV side since we need less turns of auto-transformer

sinhasunilk

 Profile Answers by sinhasunilk Questions by sinhasunilk

• Jul 12th, 2010

Voltage injection in LV side is convenient, The cable attached to LV side also need insulation suitable to LV voltage rating. If LV ia in the range of 440V and HV is of the range of 11KV, we may inject voltage in steps also through variac of 440V , Which is not possible if inject voltage in HV side.

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Why transformer does not rotate like induction motor. Inspite both having same principle?

dhananjai

• Feb 3rd, 2012

Actually in 3 phase induction motor the windings are displaced with angle of 120 degree in space that is why a rotating magnetic field is produced while in transformer the windings are concentric rather than displaced

Avishek Pal

• Jan 21st, 2012

Transformer winding is made of concentric winding but the stator winding of induction motor is made of distributed winding over inner periphery. Hence flux in transformer is pulsating in nature and st...

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Briefly explain the difference between the software testing and embedded testing?

I need the brief explanation please provide the details as early as possible

Pramod Jagtap

• Feb 23rd, 2012

The Software testing is mainly done on the software program modules and contains bug identification and its correction. On the other hand Embedded testing can be a Hardware or Software testing. In Har...

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Could you elaborate in detail about RJ11 and what does "RJ" and "11" stands for?

ajay

• Feb 22nd, 2012

Rj11 means Registered jack...it is a 6 position modular plug with 2 conductors in the middle........it s a type of communication cable.....

sunil

• Aug 11th, 2011

RJ means Radio Jack (used in US Army terminology).
RJ11 is a kind of telephone socket.

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I have installed 3 Phase Compressor(Condensing Unit) and 1 Phase Evaporator(Fan).

In this 3 Phase Compressor requires Three Phase Supply and not Neutral (which is connected to DOL starter connected) and i want to take power supply for Fan which has phase and Neutral. Whether can i loop phase from the motor and Neutral from the Control Panel. Please tell me its correct or not.

myid123dvg

• Feb 27th, 2012

Yes you can. Make sure your single phase load doesn't get any ground fault. If it happens, control supply trips, tripping the three phase load too.

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Ahmed Mohsen Fayed

• Feb 27th, 2012

Condenser (heat transfer), a device or unit used to condense vapor into liquid
A capacitor (formerly known as condenser) used to store energy in an electric field.Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass.

Mannik

• Feb 26th, 2012

Condensor is device which convert the air into water. and capacitor is used to store the electrical charge as potential difference applied on it.

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What are high pass filter and low pass filter?

anilsabaji

• Mar 11th, 2012

Read it as High Frequency Pass filter and Low Frequency Pass Filter. You have the answer

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Explain the transformer principle in terms of induced e.m.f. resulting from changing flux linkages?

Krishna Kant Gupta

• Mar 13th, 2012

when a voltage is applied in the primary winding it sets up a primary current which sets up a M.M.F which links both the primary winding and the secondary winding,this m.m.f produces a induced e.m.f ...

Bijendra singh

• Feb 14th, 2012

Transformer basically works on principal of MUTUAL INDUCTION.

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Calculate the length and the distance coved by the lightening arrestor to be installed above 20 feet height industrial building.

Krishna Kant Gupta

• Mar 13th, 2012

Lightning arrestors or lightning rods are used to arrest the lightning surges.This is based on Rolling sphere method according to the Type of protection class you are providing.Rolling sphere radius of 30M or 45M can be used.

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What causes transformer humming?

Krishna Kant Gupta

• Mar 13th, 2012

Humming sound in the transformer is due to the stray losses in the transformer due to the leakage flux.this flux produce eddy currents in the nearby conductive areas.The humming sound is the result of...

bittu123

 Profile Answers by bittu123 Questions by bittu123

• Nov 9th, 2011

Humming sound caused by magnetostriction phenomenon. Magnetostriction is change in physical dimension of material because of change in magnetic field.

Since, there is varying magnetic field in transformer causes vibration of core in gap available due to bad insulation. and starts soud hum

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It is compulsory an magnetic field to produce an current?

SHASHI

• Mar 24th, 2012

NO, ONLY WHEN THE MAGNETIC FLUX LINKED WITH A SURFACE CHANGES CURRENT IS PRODUCED,i.e when the body or magnetic lines are moving.

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Why the transmitted voltage is multiple of 11 like 11, 22, 33, 132 etc? Is their any technical reason for that?

NIMMALA RAKESH

• Mar 28th, 2012

The transmission voltages will be the multiples of 11 i.e. 11kv, 22kv, 33kv,etc., because from the transformer equation we have 4.44*f*n*phi where f is the frequency of ac input , n is the no. of tur...

veeru

• Mar 27th, 2012

The form factor of ac wave form is 1.1 so the voltage is multiple of this

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Why zero sequence component not found in two phase motors?

Harish P. Girhe

 Profile Answers by Harish P. Girhe Questions by Harish P. Girhe

• Apr 3rd, 2012

In two phase induction motors one phase & neutral is applied. For successive working of motor one phase is spitted into two equal and opposite component. These two component are having an opposite action on each other.So two phase motor works successively.

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What is the use of a voltage capacitor transformer?

sjw06

 Profile Answers by sjw06 Questions by sjw06

• Apr 15th, 2012

VCT is used to step down really high voltage to a very low voltage that can be safely fed to a measuring device or protective devices.

Harish P. Girhe

 Profile Answers by Harish P. Girhe Questions by Harish P. Girhe

• Apr 3rd, 2012

Generally all transformers works on inductive load hence operated at lagging power factor. It is necessary to use an capacitor bank for improvement an power factor. This capacitor bank called as VCT. Generally this VCT known as RVT (Residual Voltage transformer)

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Why Cable selection depends on Load current? (UG Cables & OH lines)

soumendasbiswas

 Profile Answers by soumendasbiswas Questions by soumendasbiswas

• Apr 26th, 2012

Cable selection not only depends on the load current but also depends on Temperature, Length (Distance between LT Switchgear MCC/PMCC to Motor). If load is increase then current will also increase if ...

raju

• Apr 6th, 2012

Voltage is directly proportional length, current is proportional to area of cross section of the wire.

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A 3-phase induction motor running on 500v at full load draw 40A current at 0.85 pf Lagging if 85 micro Farad capacitor connected across its terminal than what would be a New Power Factor?

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 1st, 2012

You didn't specify the capacitors connection is delta or star
assuming (delta)
Xc = 37.462 ;
reactive power drawn by capacitor = 6684.49 VAR
active power drawn by motor = 34641 watt
old power factor = .85 lag
new power factor = .91 lag

vishnu

• Feb 18th, 2012

--> Find the reactance offered by capacitor i.e 37.46 ohm. so leading current drawn by capacitor is 9.095A @90 deg lead. --> Current drawn by the motor is 40A @ 31.788 deg lag. --> Resultant current ...

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Explain what are Single and 2 Pole circuit breaker?

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 1st, 2012

Yes and single pole means that circuit switch two poles / two wires (eg; live and neutral)
3 poles used to switch 3 phase systems
4 poles used to switch 3 phase + neutral wire
5 poles used to switch 3 phase + neutral + ground wire

amolgaonkar

 Profile Answers by amolgaonkar Questions by amolgaonkar

• Dec 9th, 2011

Circuit Breaker is a safety device used to safeguard electrical equipments from heavy current, it trips OFF when more than rated current passes through it.

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