Why OC test is carried out on low voltage side of transformer?

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 3rd, 2012

The previous answers are right + to make an accurate measurement O.C test on LV side because the current is high on the low voltage so when we repeat the experiment we will get more results with the ...

Pratyush Singh

 Profile Answers by Pratyush Singh Questions by Pratyush Singh

• Jul 26th, 2011

Because during OC test, rated voltage is applied, hence the HV side is unsuitable to keep instruments, hence it is the HV side that is opened and the LV side is where instruments are placed (at their rated values)

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If Heater of 1000W is connected in series with 60 W bulb. what is the effect on the bulb.

SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• May 5th, 2012

1 Thing everybody has to remember is that only current and not the voltage remains constant across the elements.Let us assume that the elements in series are connected to 220V supply source. Total po...

bittu123

 Profile Answers by bittu123 Questions by bittu123

• Nov 9th, 2011

@ om_zzz

You are right, bulb will glow but dimmer and heater will not heat-up(more precisely it will generate very less heat)

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What is the benefit of using ac signal in a transformer?

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sinhasunilk  

 Profile Answers by sinhasunilk Questions by sinhasunilk

• Member Since Jul-2010 | Jul 3rd, 2010

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Transformer can only operate with A.C supply. Voltage will induce in the secondary winding of transformer only when there is a change in flux. The induced voltage in the secondary winding is no. of turns in secondary x rate of change of flux. In D.C circuit the rate opf change of flux is Zero, hence induced voltage in secondary winding is Zero and no Back MMF produce in the magnetic circuit of core of transformer.?This will result in very high current drawal in the primary winding and will result in burning of primary winding of transformer. We can not think of applying D.C source in transformer.??

SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• May 5th, 2012

The reason why dc signal cannot applied to a transformer is that f=0,reluctance is 0,very high current flows through windings and it is burnt out!

sinhasunilk

 Profile Answers by sinhasunilk Questions by sinhasunilk

• Jul 3rd, 2010

Transformer can only operate with A.C supply. Voltage will induce in the secondary winding of transformer only when there is a change in flux. The induced voltage in the secondary winding is no. of tu...

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What will happen if voltage applied to a load is less then the rating specified ?

ahmed

• May 7th, 2012

The load will not work right as its performance design

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A 3phase wye/delta transformeris rated 225kV/24kV, 400MVA and has a series reactance of 13.3ohms as referred to its high voltage side. The transformer is supplying a load of 325MVA at 0.9 pf lagging at a voltage of 24kV(line to line)on its low voltage side. It is supplied from a feeder whose impedances are (0.15+j1.5)ohms connected to its high voltage terminals. For these conditions calculatea> The...

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 10th, 2012

???
incorrect information
you should specify at least on of the terminals voltages

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What types of tower & pole is used in power system distribution?

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 14th, 2012

For lattice metal structure (High Voltage )
they can divided into (specifying the job)
suspension , angle , end , cross towers

raviiisc

 Profile Answers by raviiisc Questions by raviiisc

• Sep 8th, 2010

I think "_punjabi_" forgot about the concrete poles or towers.These towers are more practical in now a days in Power distribution sector.

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List various methods to convert 1 phase to 3 phase.

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 14th, 2012

This can be done with thyristors

raviiisc

 Profile Answers by raviiisc Questions by raviiisc

• Sep 8th, 2010

This conversion is done by using mainly two methods. They are:1. Convert 1-ph ac to dc by using power electronic converter then convert that dc to 3-ph ac using power electronic inverter using PWM...

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In a 50hz electrical machine what happens when we use more than or less than 50hz?

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 14th, 2012

Frequency affects on the speed and torque of the machine and thats is the principle of the drives

_punjabi_

 Profile Answers by _punjabi_ Questions by _punjabi_

• Aug 29th, 2010

Speed and torque of the Electrical machines can be regulated by chanigng the supply frequency. Also harmonics produced are different than normal operation

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If I got a 380v 3-phase supply and I want to rectify it with thyristors to single phase how much voltage will I get ?What is the relationship?thanks

SGhosh

• May 15th, 2012

The dc output of the full wave rectifier is average value the amplitude of the sine wave. In short multiply the r.m.s value of the ac input voltage by its form factor (1.11 in case of pure sine wave) ...

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 15th, 2012

I know the output will be dc my question is how much dc voltage will be the output

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If you make a capacitor out of aluminum plates,
and electrically glue carbon or resistive plates to the aluminum ones, and use a dielectric between the sets of plates.

where the input is on the aluminum plates
where the output is on the resistive plates.

Would it charge quickly thru the aluminum plates and discharge slowly thru the resistive plates.
Making...

SGhosh

• May 15th, 2012

The capacitor would definite charge faster when a voltage source is connected to the Aluminum plates. The semi conducting layer will provide smoothness in the equipotential lines and reduce the voltag...

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What size of grounding conductor should be used to ground an XLPE metallic screen?
Is there an international standard that supports it?

Thanks

SGhosh

• May 15th, 2012

The Indian & International standards for grounding are IS 3043 & IEEE 80 respectively. The size of the ground conductor for grounding the screen of an XLPE cable depends on the calculated ground fault...

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SGhosh

• May 15th, 2012

Cable glands serve the following purposes:

1. Fixing the cable mechanically to the panel.
2. Making proper electrical bonding of the panel with the armour of the cable (grounding).
4. Ingress protection to the panel after cable termination.

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How much output will reduce , if 25 mw, 13.8 kv, 1800 rpm alternator runs in 1500 rpm 50 hz? What are the disadvantages if continuously run in 1500 rpm?

SGhosh

• May 15th, 2012

Voltage will reduce by a factor 1500/1800. Reduction in output of the generator does not solely depend on rpm. The various other factors associated with the operation of the prime mover and load will govern the output.

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We have a 3 phase induction motor, having stator length greater than rotor length by 10mm. my question is that, is this will affect the operation of motor (means cause an abnormal condition like temp. rise etc.)?

SGhosh

• May 15th, 2012

In my opinion, only in case the rotor is not centered axially with the stator will lead to vibrations. The difference in the lengths of the rotor & stator will lead to more leakage flux leading to poo...

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SGhosh

• May 15th, 2012

The loop keeps on rotating in the same direction irrespective of the position of the conductors cutting the magnetic flux. Magnetic flux does not change its direction either. The only things which kee...

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As all we know,induction stove works on the principle of electromagnetic induction.Thus an emf is induced in the vessel and eddy current flows through the vessel.Since the vessel is made of ferromagnetic material (high resistivity) larger amount of heat (H=I^2 R)is generated.What will happen if a human body comes into contact with this high resistive vessel??? Won't the human body resistance be parallel...

SGhosh

• May 15th, 2012

Human body under dry condition has much higher resistivity compared ferromagnetic material.

mahmoudp1

 Profile Answers by mahmoudp1 Questions by mahmoudp1

• May 5th, 2012

Ferromagnetic material is higher

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What is the standard size of a model of an electric tower for lab exhibition?

Why are we employing star type transformer at transmission end and delta type transformer at receiving end?

UMESH KUSHWAHA

• May 23rd, 2012

Its not necessary to use only Delta type T/F at receiving end, we can also used star type but in this case at same voltage level two star neutral point create due to which Harmonic create for avoiding this we prefer opposite combination at sending end and receiving end.

vishal badlas

 Profile Answers by vishal badlas Questions by vishal badlas

• May 19th, 2012

Bcoz at the transmission side especially for secondary distribution we need neutral wire for getting single phase supply and star type is only one which provide neutral. at receiving side to step up voltage we need delta type connection.

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How we can step-up or step-down the DC voltage directly?

S.Ghosh

• May 23rd, 2012

A chopper is nothing but a thyristor/SCR/transistor circuit which operates with the principle of PWM (Pulse Width Modulation). If you need to boost DC voltage with chopper, additional circuits includi...

sai charan

• May 20th, 2012

this can be done by using chopper.chopper is a dc equivalent of a.c transformer to which d.c input which is to be stepped up is applied at input terminals and output is taken from output terminals whi...

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I mean which applications should require any of the above circuit breakers.

SGhosh

• May 23rd, 2012

MCBs have relatively low breaking capacity and sluggish compared to fuse. Fuse is used when cost of cable is a factor. If MCBs are used proper cable sizing must be done considering fault level and duration.

SPI

• Apr 24th, 2012

Fuse is old technology to break d circuit in fault. MCB is for low fault currents starting 6Amps to, 63Amps either 1Phase or 3Phase. And (b,c,d,k) are depends on the fault current and the location u r going to use. MCCB for higher currents more than 63 Amps that to in 3 Phase only.

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