What is Phase Swinging or Hunting in Induction Motor?

Sushma vasudev ningappanavar

• Oct 14th, 2015

Swinging

Hari

• Oct 12th, 2015

When a synchronous motor is used for driving a varying load, then a condition known as hunting may occur. Hunting may also be caused if supply frequency is pulsating (as in the case of generators driv...

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How to measure the cross-sectional area of a cable which is 1000 sq. mm.?

Heaven

• May 24th, 2016

3.14 x radius of cable^2

KHURAM

• Dec 10th, 2015

A=pi*r^2

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you have three boxes, one has a resistor, second has a capacitor, and the third has an inductor. Find what is in each box, using a battery, a switch and a lamp. You can build any circuit you want, to figure out which box have a resistor, and which one has the inductor, etc. How can you solve that?

chandramvs

 Profile Answers by chandramvs Questions by chandramvs

• Jan 3rd, 2016

Connect the battery, switch, lamp and the box in series and observe what happens, 1) If the lamp glows with constant brightness then the box has resistor. 2) If the lamp initially is dark and finall...

abdelmonsef

• Jan 2nd, 2016

A battery is DC, so when connecting the battery and the capacitor and the lamp in series, the lamp will not be on (as the capacitor is open circuit in DC system) and when connecting the battery and th...

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What is the difference between half controlled and full controlled rectifier? Why we go for full controlled while half controlled can control voltage?

k.r.kartheeswari

• Apr 10th, 2017

In Half controlled rectifiers, the controlled output will be in one half cycle, so the efficiency is less. But in full controlled rectifies, the controlled output will be in both the half cycle since both the sides having SCRs. So efficiency also doubled compared to half controlled.

pradeep1987

 Profile Answers by pradeep1987 Questions by pradeep1987

• Feb 4th, 2016

Diode is uncontrolled and SCR is fully controlled element. In SCRs we can turn ON and OFF by gate pulse or by the other means. Whenever the diode is used in rectifier, the rectification is done by the...

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The input impedance of cascade amplifier will :

a. Same as input impedance of first

b. Same as output of second.

c. Same as the entire circuit

d. Same as Stage before the last stage

Jayakumar

• Aug 27th, 2021

Same as input impedance of firdt

mohammad

• Jan 24th, 2016

B. Same as output of second.

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Why frequency should remain constant in Grid? If it varies then what will happen to other generators?

Ashu the Sharp

• Feb 2nd, 2017

Because Power will vary and rest of generators will loose sync

Jay-quellin

• Feb 8th, 2016

It synchronizes the generators, which would run out-of-phase if they dont all run at the same frequency. Power would not be constant. Imagine a digital and analog clock. The analog clock will keep tra...

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What are the advantages & dis-advantages of Harmonics in Power System?

Qaphelani Sgcino

• Apr 2nd, 2016

Disturbances in the communication networks and telephone lines.

Kevin

• Mar 27th, 2016

Disadvantages of Harmonics: Harmonics degrades the performance of power system. Some of the disadvantages of harmonics in the power distributed network are listed below: The harmonics flowing in the...

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Dear All,
I have a done a house hold wiring for villa, During a megger test we notice that valve between phase and neutral is good 500 Mohm when test between Phase to earth wire it is shown as less than 100 Mohm when I remove the all wire from conduit and we test it is showing correctly as 500Mohm, After that i replaced all wire as New before pulling the wire in conduit i checked it is shown...

Edwin Rodrigues

• Aug 3rd, 2016

The conduit probably has moisture or humidity. Or the temperature of wires inside the conduit has increased. The insulation resistance depends on factors of humidity and temperature.

bhanu

• Jul 21st, 2016

Megger which is used to find the discoonection in the underground cables

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What is meant by strung bus and where is going to be used and what is purpose of it?

arun

• Aug 29th, 2016

Bus bar is used only in MV panel and SSB

Dhanashri

• Aug 1st, 2016

The strain bus-bar is a flexible, stranded conductor which is strung between substation metal structures and held by suspension-type insulators

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Night time load on our system street lights, one DG battery charger-24v, 6 KVA UPS. On UPS only 12v solar fencing battery. You are suffering from leading pf. Can you say how to improve pf?

ashish dubey

• Dec 18th, 2016

We can improve the pf by reducing the harmonics.

vivek

• Sep 30th, 2016

By shutting down the capacitor bank.

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In a panel, I have following loads with respective power factor,
load A - 0.85
load B - 0.8
Load C - 0.9
How to calculate the Overall power factor of the panel, whether I have to take average or I have to consider the lowest?

Michael McCormick

• Nov 3rd, 2017

One needs to know the overall magnitude of each load in addition to power factor. Devolve each load into its real and imaginary components and add them vectorially.

murugan

• Nov 16th, 2016

Average(.85+.80+.90)?3=0.85 is answer

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When DC is applied, Transformer goes in to saturation, What happens if DC Pulses are applied, will this be safe? Will it act as transformer?

Pradeep Mewara

• Mar 29th, 2017

If we apply DC to the transformer, the nature of DC is constant magnitude so constant flux generate in primary winding there is no change in flux so EMF will not induce excepting when switch ON and switch OFF. If DC is continually supplied to the primary it will burn.

Ravi

• Mar 7th, 2017

When DC applied to Transformers the induced emf is zero in primary because of steady current, which leads to heavy current flow coz only coil resistance is connected directly to the source. Which dama...

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What is the difference between volage control device and Current control device

ENGINEER: ALJABRBI SALMAN

• May 3rd, 2020

A BJT is a current controlled device because its output characteristics are determined by the input current while a FET is voltage controlled device because its output characteristics are determined by the Field which depends on Voltage applied

M SIVARAJ

• Feb 27th, 2020

1.IN VOLTAGE CONTROL DEVICE VOLTAGE WILL BE CONSTANT & CURRENT WILL BE VARY
2..IN CURRENT CONTROL DEVICE CURRENT WILL BE CONSTANT & VOLTAGE WILL BE VARY.

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anilsabaji

 Profile Answers by anilsabaji Questions by anilsabaji

• Dec 29th, 2010

Yes it is possible

anilsabaji

 Profile Answers by anilsabaji Questions by anilsabaji

• Dec 29th, 2010

Surge can pass wirelessly.. Look at lightning surge

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Rahulshelke

 Profile Answers by Rahulshelke Questions by Rahulshelke

• Jul 12th, 2010

During fault to have shortest resistance path is ground. Hence current flows through ground. hence we take 30inch during calculation.Voltage difference is created and current flows.

zakeer

• Aug 30th, 2007

We are taking earth as reference it means it's?potential is not absolutely "ZERO" but approximatelly it is zero .and the potential is not equal allover the earth it varies from place to place so we measure at 30 m in to earth

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SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• Apr 19th, 2011

We know flux(phi)=NBA cos(teta)e=-d(phi)/dttherefore on differentiating we gete=NBAw sinwt.ie.sinusoidal wave.Moreover when 3 phase are displaced by angle 120 with respect to each other,rotating magnetic field is produced.

cvk

• Oct 6th, 2007

Reson 1 is the way power is generated. Due to the construction of generators, the default wave form is sinusoidal. Secondly, the frequency of sine wave is a single definite value while other wave form...

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rahulr30

 Profile Answers by rahulr30 Questions by rahulr30

• Jun 8th, 2008

Sine wave is best suited for commercial generation purposes because it will have a single unique frequency. I f we genrate a square wave ( by using concentrated windin in alternator) the problem of harmonics would arise.

cvk

• Oct 5th, 2007

It is by the natural construction that a sine wave form is generated.

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In syncronous machines, less slip is useful or more slip is useful? Why?

Harry Sandha

 Profile Answers by Harry Sandha Questions by Harry Sandha

• Apr 24th, 2011

Slip is 1 in sync.mtr

venky_sastra

 Profile Answers by venky_sastra Questions by venky_sastra

• Dec 28th, 2008

A synchronous machine is defined as a machine which rotates with the constant speedslip= Ns-Nr/Nssince in syn m/c Ns=NrS=0The significance of slip comes only in induction machines where the slip exists.

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What is mean by reactive power? How it is generated?

Sreebai

 Profile Answers by Sreebai Questions by Sreebai

• Sep 21st, 2010

Reactive power is the power required to transmit the active power. The reactive power is like an envelop,that is used to send a letter. Without this we cant send the active power and it cant be too hi...

SURAJTHEGREAT

 Profile Answers by SURAJTHEGREAT Questions by SURAJTHEGREAT

• Mar 3rd, 2009

We know reactance (hypothetical resistance) which reduce the supply voltage by opposite flowing induced emf. This power loss due to reactance is known as reactive power. This power is not useful power. It is a waste. However it is useful in determining the phase angle.

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What is mean by form factor of the AC current?

Mohammad Ibrahim

• Jul 21st, 2011

2) In electric motor terminology, a form factor is the amount of rectified current emitted from a direct current (DC) power source and is expressed as a ratio of the root-mean square (rms) value of th...

ramu nit

 Profile Answers by ramu nit Questions by ramu nit

• Apr 15th, 2009

It is the ratio of rms value to average value of an alternating quantity.

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