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How size of UPS depends on frequency?
How size of UPS depends on frequency? I mean proportional, inversely proportional or proportional to square of frequency?
Umair Anwar
- Nov 13th, 2014
Because core size of transformer directly depend on frequency and transformer primary element.
bittu123
- Nov 8th, 2011
Actually i mean SMPS not UPS.
Please moderator, if you can change my question please do it.. Replace UPS by SMPS since i didn't get any option to edit my question -
Meaning of RJ11
Could you elaborate in detail about RJ11 and what does "RJ" and "11" stands for?
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What is welding transformer ?
Why we use it in welding and what is the difference in welding and ordinary transformer?
Srinivas
- Dec 20th, 2011
Welding transformer is used for welding purpose, these are the special type of Transformer. which will be having only few turns on secondary side of the transformer winding. it will operate at low voltage in the range of 60 to 110 v Ac where as current will be very high upto several thousand amps.
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What is the use of a VCT
What is the use of a voltage capacitor transformer?
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
- 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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Supply Voltage 220V, 110V or both
Why do some countries have 220V supply while some have 110V and some even have both ?
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Induction Motor Power Factor
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
- 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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Making electricity
Can electricity be made by reversing. Other words can you make electricity by spinning magnets around copper wiring
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Power Produced in Generator is either ACTIVE(kW) power or APPARENT (VA)
Power generated in the generator is active power or apparent power? Will there be any phase lag while generating power? How the reactive power is produced (either by capacitor or the generator itself generate it) ?
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Explain about polarities ?
- Dec 11th, 2013
Polarization is a complex subject? But is easiest understood to me a position, location, direction, depth and etc. from a center point of refrence it is easiest understood by ceating a sphere around t...
Yasser Ali
- Nov 1st, 2013
Polarity may refer to: In science: Polarity (mutual inductance) Polarity (physics), a physical alignment of atoms Cell polarity, differences in the shape, structure, and function of cells Chemical po...
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3 phase induction motor
prove :
average power = instantaneous power
in 3 phase induction motorripplenwinder
- Dec 11th, 2013
We can define the 3-phase voltages as: 1) v1 = Vp x sin(u); 2) v2 = Vp x sin(u +120); 3) v3 = Vp x sin(u -120) 4) vn^2 = v1^2 + v2^2 +v3^2 = K 5) sin(u +/- v) = sin(u)cos(v) +/- cos(u)sin(v); 6) sin^...
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Impedance matching
Explain briefly about impedance matching and how the transformer serves in impedance matching?
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Transformer design and construction
What is shape of the coils used in a transformer ? choose the correct one from the bracket (rectangular,oval,circular,cylindrical ) & justify it with detail reason.
Is transformer a machine ?choose the correct one from the bracket (yes/no) & justify it with detail reason.
manikandan.l
- Jul 18th, 2014
Rectangular
AlHussein Abdallah
- Jul 17th, 2014
Star connected rotor of induction motor has a standstill impedance of (0.4+4j)ohm per phase and rheostat impedance per phase is (6+2j)ohm. The motor has induced voltage of 80v between slip-rings at st...
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Power System
Difference between pi and pid controller
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Path of current in domestic loads
I am confused about the path of current in domestic loads . In the negative cycle does the current flow from neutral to the phase.wont the whole system get grounded then if we use a single phase ground return?
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IES
How can I prepare for Ies from 2nd year onwards?
shailesh
- Aug 1st, 2015
By applying for IES Exam online
chandramvs
- May 29th, 2015
First of all your core subjects begin from 2nd year only.so be strong with your B.E/B.Tech subject. If you have good faculty then go on par with them and study the complete subject within the same se...
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Why star delta starter prefer to D.O.L starter for large motors?
We prefer star delta starter for reducing start voltage but Normally in D.O.L starter-motor is always connected in star - it will also start in reduced voltage.... Explain
saeed iqbal
- Jul 24th, 2015
In starting motor gets 3 to 4 times more current then its normal current. So we use star delta starter to limit the starting current of the motor with the help of star circuit.when motor will run in t...
Ahmed Elsisy
- Jul 22nd, 2015
In large motors: when motor start it draws a large current in starting , so we use star delta method to reduce this current in starting by Firstly we connect motor on Start (motor no loaded) on low v...
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