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AC Generator
To induce EMF, either field has to rotate or rotor has to rotate. In Alternator, AC supply is given to the armature to produce rotating magnetic field. The rotor is rotated by the prime mover. Then how will EMF be produced in an alternator. Explain the working principle of alternator in detail?
manilal.r
- Jan 2nd, 2011
Like a DC generator, an alternator also has an armature winding, but there is one importent difference between two, in a DC generator, the armature winding placed on rotor in order to convert AC? to ...
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Dielectric Strength
What is dielectric strength?
Harish P. Girhe
- Jan 4th, 2011
Material can be conductive or non-conductive. It depends on its di-electric property of that material. Di-electric means property of an material to oppose flow of electrical current. For better condu...
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Wattmeter Circuit
Why pressure coil is named so in wattmeter circuit?
Harish P. Girhe
- Jan 4th, 2011
Current & voltage both requires for utilisation. Current depents on device for its energirising. Each individual device reqiures currents for its own working. But voltage is applied across device term...
prabhat.gaurav
- Dec 8th, 2009
As pressure in pneumatic sysytem is analogaus to voltage that's why the coil connected to supply voltage in wattmeter is called pressure coil.
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Line Wire
When we touch the line wire or supply wire we get shock. What is that? Is it voltage or current or something else?
Harish P. Girhe
- Jan 14th, 2011
Voltage is responsible for electric shock. In house wiring only 5 or at least 10A current flows but potential diff. of 230V get disturb our nervus system. Human body(dry) can sences above 80volt without any danger.(Not every time)
_punjabi_
- Aug 29th, 2010
When you happen to touch the live part of the supply, then your body acts as a part of the circuit and of the Supply system is not grounded and if equivalent resistance of your body is less than that ...
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AC & DC System Components
In DC only resistive component exists where as in AC system resistive, capacitive & inductive component exists. Why its so?
Harish P. Girhe
- Jan 16th, 2011
It is because of loads reactance. Reactance either capacitive or inductive that depends on frequency. XL=2(pi)FL Where f is supply frequency. In DC supply f=0 hence XL=zero. Similarly Xc=1/2(pi)F.C=0 in dc supply. Thats why only resistance is to be present in DC system.
arjun karnati
- Jan 19th, 2009
Good question. to answer this question first of all we need to study the terms resistance, inductance, capacitance on atom level. Generally what we know is Resistance: which opposes the flow of electr...
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Alternators
Which slots does a stotor of an alternator rarely uses?
veerateja
- Jan 22nd, 2011
Open type slots are used in synchronous motor or alternator because to reduce the leakage reactance and leakage flux,which increases if closed slots are used.
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Fan Condensers
Why condensers are used in fans?
veerateja
- Jan 28th, 2011
Fan condenser is just used to create starting torque by increasing the current lead through the starting winding ,after started running of 1-phase motor we can remove capacitor even after removing the...
shafialuva
- Sep 15th, 2010
The most common motor used in a normal household electric fan is a single-phase induction motor. When first switched on such a motor needs to use a "starter" winding, in addition to its ma...
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Location of Circuit Breaker
The designed capacity of the transformer was 1600 watt. The utility company is in shortage of such wattage, so they used two 800 watt transformers in parrallel. The utility company uses only one circuit breaker after the parallel connection. The custmer says it is not correct there should be two separate breakers for each transformer. Which connection is accseptable.
VEERENDRAKUMAR.CH
- Jan 28th, 2011
when one CB used:if fault occurs on any one transformer that fault will effect the another transformer so two CB must be needed
appersundaram
- Mar 27th, 2010
We can use two circuit breakers in parallel, but we should connect the mastertrip relay contact of either breaker should be wired to trip the other breaker as well.
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Two Phase Induction Motor
What is a Two Phase Induction Motor?
sandeep.psg
- Mar 2nd, 2011
2 phase Induction motor(IM) has 2 sets(phase) of coil displaced electrically by 90degree. In practise we dont have dedicated 2 phase IM because of not supplying Constant Torque. But we do have so...
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Transformer Secondary Voltage
Why is it that the secondary voltage of a step-up transformer is lesser than the primary voltage of a distribution transformer?
Jai Pradeep
- Mar 13th, 2011
The primary voltage of a distribution transformer decreases due to increase in length of the conductor between step-up and distribution transformer.
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Power Consumption
A heater of 1500w, bulb of 100w & 40w are connected respectively as sequence as stated above across supply. What effect will be observed on illumination/power consumtion of all of them?Now sequence is changed as bulb of 40w then heater & last bulb of 100w. What effect will be seen on illumination/power consumption of all of them?
Jai Pradeep
- Mar 13th, 2011
In the first method?the heater with 1500Watts connect, i.e large load is connected in first of a sequence so most power consumed by this. The 100 & 40 watts bulb will illuminated lighter.In the seco...
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Apparent Power and Reactive Power
What is apparent power and reactive power?
Steeve Cantave
- Mar 15th, 2011
Apparent power is the power that is needed for the circuit to perform. In an AC circuit with resistive, capacitive, and inductive components, not all power is converted from electrical to non-el...
zaheerdahri
- Dec 23rd, 2010
Apparent PowerApparent power (S) is the power delivered to an electrical circuit. The measurement of apparent power is in voltamperes (VA).Reactive PowerReactive power (Q) is the power consumed in an ...
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Quiescent Point
What is a Quiescent Point (commonly called a Q-point)?
uttkarsh BIT
- Mar 26th, 2011
Quiescent or Q-point of any device is the intersection point of its characteristic curve and a given load line(or load curve). It actually is the most suitable point around which the device works under maximum efficiency.
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Why is r.m.s. value used to express a.c. quantities?
SURAJTHEGREAT
- Apr 10th, 2011
AC values are always alternating.Hence we cannot make a precise analysis!!!!So we use RMS value.Let us consider a bulb B.IF it is switched to position A(it is connected to ac supply).IF switched to po...
raviiisc
- Apr 9th, 2011
The rms value arised in the following manner:The heat dissipation with AC supply will found, then the DC supply is applied such that same heat production in resistor. That DC voltage value is said to ...
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Why we are using Sinusidol wave in all electrical systems?
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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How do we select a cable for a machine as per standards. Is there is any standard to select a cable as per voltage, or as per KVA and as per amps ratings?
prafulla patil
- Nov 15th, 2010
Cable size depends upon current carrying capacity and operating Voltage of Machine to select cable size also the Distance from the Supply Panel to Machine and way of laying cable under ground or on ca...
jatin patel
- Oct 16th, 2007
Cable size depends upon current carriying capacity and voltage to withstand,to select cable size we must have knowledge of load of machine and operating voltage
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What is the voltage that is supplied to the electric traction trains
nileshvalvekar
- Aug 12th, 2009
Above both answers are correct but at some level. The ans. should be 1) 25 Kv Ac system2) 1500 V Dc systemabove voltages are used depending on the system being used.
haveasafeday
- Feb 5th, 2008
Right that it is 25kv ac. But the traction motor is a DC series motor for on-load starting.
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What is the reason of power development in synchronous generator due to saliency ?
abishgk
- Aug 13th, 2010
In salient pole synchronous machine has non-uniform air gap so the reactance will vary with rotor position. It has mainly two axis are there 1. Direct axis 2. Quadrature axis.
santosh soni
- Dec 21st, 2006
IN SALIENT POLE SYN. ALTERNATOR IT IS THE CHANGE IN THE RELUCTANCE WITH SPACE WHICH RESULT IN GENERATION OF BOTH RELUCTANCE POWER & ELECTROMAGNETIC POWER.
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Syncronous Machines Slip
In syncronous machines, less slip is useful or more slip is useful? Why?
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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How is a 100 MVA transformer cooled?
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