what is lightning Arrester? what the use of this in substations?

rakshay sharma

• Oct 18th, 2011

LA-- nothing but a metallic conductor provided with grounding, to arrest natural lightnings, in order to protect electrical equipments.

mahesh

• Oct 14th, 2011

Lighting arrester are used at substation to protect the transformers from surge currents and pass the surge current to earth

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prasad jandhyala

• Sep 6th, 2014

Synchronous motor acts as a condenser when it is operated at no load and over excited state. synchronous condensers are mainly used for power factor improvement.

Pramod kumar

• Sep 3rd, 2014

Synchronous motor behave as a condenser when it uses at no load and leading pf.

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Is there any case that we could face or find Voltage without Current and Current without Voltage?

N K WATTAS

• Aug 10th, 2016

1) Voltage without current:This situations can also happen when current is leading by 90 degree as compared to voltage.
2) Current without voltage: this situation can happen when current is laging voltage by 90 degree.

Mandeep kumar sinha

• Aug 10th, 2016

I know voltage without current when there is open circuit and current without voltage in the case of short circuit

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Harry Sandha

 Profile Answers by Harry Sandha Questions by Harry Sandha

• Apr 24th, 2011

With forced air and cooling oil

transformer01

 Profile Answers by transformer01 Questions by transformer01

• Jun 12th, 2010

It is cooled by OFAF that is oil forced, air forced.

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What do you mean power factor?What is the use of Power Factor?

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rahulr30  

 Profile Answers by rahulr30 Questions by rahulr30

• Member Since May-2008 | May 30th, 2008

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Power factor is the ratio of Active ppwer to apparent power in sysytem,It is an index to see how much of the energy is actually being utilized to do useful work

veerateja

 Profile Answers by veerateja Questions by veerateja

• Jun 11th, 2011

pf is the co-sine of phase angle b/w voltage and current.Generalley it is leading or lagging depanding on the load whether it is inductive(lag) or capactive(lead).Take voltage as reference the current...

srdpriya

 Profile Answers by srdpriya Questions by srdpriya

• Jan 25th, 2011

It is the cosine of angle between Voltage and Current

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Why SC test is performed on LV side?

Umesh

• Sep 25th, 2014

We generally performs Short circuit test keeping initial voltage at lower value and then gradually increases it up to the level to get a full load current (or Max) through testing device or circuit. B...

KM Mahesha

• Jul 22nd, 2014

Load are in LV side and also max SC faults occurred in Load side. If SC Faults occurs protect load and Net work system

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sudhakar srivastava

• Jan 6th, 2013

In AC, phase is present but in DC, negative and positive terminal is present.

vishal rana

• Nov 5th, 2012

Alternating current which magnitude change with time and D.C is magnitude dose not change with time its always same.

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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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atul sudhakar

• May 2nd, 2014

Increased frequency causes increased losses and we yet don't have the technology to have the strong foundation to keep machine running at that high frequency

ripplenwinder

 Profile Answers by ripplenwinder Questions by ripplenwinder

• Dec 10th, 2013

In power transmission it cant due to EFIENCY and COST. The higher the frequency the more it is essentialy a direct current! so 100HZ has more power loss due increased current lower peak voltages at th...

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What is the difference between a capacitor and a condensor?

ripplenwinder

 Profile Answers by ripplenwinder Questions by ripplenwinder

• Dec 11th, 2013

There is no difference with the exception or semantics and argument. Tesla use to call a capacitor a condenser we now call a condenser a capacitor. Schematics symbol for both are the same!

Pruthvi

• Oct 21st, 2013

Main diff. b/w Condensers and capacitors are
i. Condensers are rotating while capacitors are static
ii.Smooth flow in KVAR can be obtained through condensers while it cannot be obtained through switching capacitor banks.

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What is the difference of h.t and l.t. cables ?

RAHUL LOHIYA

• Feb 5th, 2014

GENRETION TRANSMISSION DISTRIBUSTION

sanket

• Oct 2nd, 2013

L.T. means low tension use for below 1000 volts normally pvc cables
H.T. means high tension cable use for more then 1000 volts normally are xlpe shielded cables

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Why neutral point is not required in high transmission line?

Karuppiah arumugam

• Apr 27th, 2015

Power system ?having Generation,transmission and distribution . Distribution transformer only need neutral ?becoz we need lighting load supply. 230V ?(phase to neutral 230v) in the transmission system only we sending voltage from one end to another end?

SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• May 5th, 2012

HVDC Transmission lines are carriers of power,they are not source of generation.if there is any fault in HVDC,the extra current has to flow through generator,transformers...since alternators and trans...

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We know synchronous machine run at a constant speed.Consider Synchronous motors, If you load the machine, will the speed reduce? If it does so, then it prohibits the property of synchronism. So Explain What is happening?

maverick

• Mar 28th, 2015

In synchronous machine speed always remains constant even when load on it changes. For increased load motor develops increased torque because of rotor falling out of phase by large angle delta; which...

bittu123

 Profile Answers by bittu123 Questions by bittu123

• Nov 10th, 2011

Even if you increase the load on synchronous motor upto specified limit, SPEED will NEVER fall down(unlike dc or induction motor), while maintains synchronous speed. BUT why??? It takes more current ...

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sandeep chauhan

• Mar 16th, 2015

There is no similarity in Neutral & Earth , i.e these are the two different topics.

However , Neutral is connected to Earth at the source to ground the unbalanced current in the electrical network mainly in distribution system

Karuppiah arumugam

• Feb 18th, 2015

In distribution t/f ?earth is acting as neutral?

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tanweer salim

• Nov 21st, 2013

Ups uninterruptible power supply

nazmul haque

• Jul 16th, 2011

Uninterrupted Power Supply...............

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saginala13

 Profile Answers by saginala13 Questions by saginala13

• Jun 19th, 2010

Hey SCR means Silicon Conrolled Rectifier.........it is used in powersystem applications.

Mohamed saad

 Profile Answers by Mohamed saad Questions by Mohamed saad

• Apr 29th, 2008

in another way of diffenationsthe thyristor can be diffened as a valve controlling flow ( current) to have this flow we have to open this valve ( by the gate pulse) the flow will be continous unless the flow is enough

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What is the diffrence between Altrnator & Generator? Outline its working principal.

satyaprakash sahu

• Apr 12th, 2015

As the main difference between alternator and generator is that field winding(poles) in a generator are present in stator i.e is fixed and armature winding is rotating whereas in a alternator the pole...

nimmala rakesh

• Mar 28th, 2012

Alternators and generators are the two devices which generates electricity.. the function of these are same but the construction of it is different. in alternators the armature is stationary and the m...

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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 the transformer neutral point connected to earth?

GARGI VERMA

• Jul 30th, 2015

In Simple words, There are two type of losses in a transformer; 1. Copper Losses 2. Iron Losses or Core Losses or Insulation Losses Copper losses ( I2R)depends on Current which passing through tran...

Ayaz Shaik

• Jun 30th, 2015

It does not mean always the t/f neutral is connected to ground..only in case of power t/f it happens mainly for two reasons 1) We know all things like harmonics, fault occurrence, lightning, over cur...

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chanchal

• Jun 5th, 2016

Earthing is inside of earth with any conductive material and grounding is on top of the earth for machines (grounding can be with high ohms but earthing must be with 0.1 ohms)

harsha vardhan

• May 2nd, 2016

In my case both are similar

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