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Motor Rating
Can we use a 15kW, 1450rpm motor for 15kW, 960rpm apllication?If yes, what will be the drawbacks?
awanish75
- Nov 20th, 2008
IR value/winding resistance (should be same for three phase) should be checked in HT motor but in IT IR value will only do.
thomas_alva_edison
- Nov 20th, 2008
If the application is designed to be driven by a 15 Kw, 960 RPM motor, then:If you directly connect a 15 kW, 1450 RPM motor, you will be driving the equipment 50% faster than it is designed to operate...
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Current Transformer Protection Class
What is the 5p 10 , burden in current transformer?
sanjay.patel
- Nov 28th, 2008
It means CT have minimum inaccuracy is 5% when it experiences 10 time of it's rated current.5 is minimum% inaccuracyP mean Protection Class10 How much time of rated currentis Rated current
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BusBar
What is a busbar?
manojprabu
- Mar 22nd, 2009
Busbar is nothing but just a cable in which two or more alternator or transformer are connected after synchronising them as single cable foe connecting to load
Nwannaa
- Jan 22nd, 2009
A busbar is the metal bars of copper or alluminum depending on design that are installed in panels. The bars are dimensioned according to stipulated current carring capacity and installation type.The ...
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Alternator Regulation
Why most of the alternator is connected in star and have high regulation around 30% as compared to transformer?
sinuhe
- Dec 7th, 2011
There will be a large amount of third harmonics in current flowing "inside" the delta connected generator.
Raman Jain
- Dec 3rd, 2009
The cost of insulation is the deciding factor . If one is using delta connection , the insulation required will be for Ph-Ph voltage but in the case of Star connection the voltgae will be 1/1.732 times. So cost will be less.
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Save Power
Suppose the electricity board gives 11 kw, but the machine requires only 8 kw in such case how can we save the excess power?
bittu123
- Nov 9th, 2011
Guys, Do u really think electricity board give us power in kw??? No, We demands power as our requirement. This assumption is wrong of giving power. Suppose, In your house, 1 bulb is switched ON, so U...
rajakumar1985
- May 15th, 2009
Even the supply is capable of deliver more power than the required power, the machine will take howmuch power that needed.
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3 Phase
Why there is 220v in 1-phase but 440v in 3-phase?
rajakumar1985
- Aug 13th, 2009
The output of generator having 120 degree phaseshift. Ever time the instantaneous magntiude will be root 3 times the phase voltage. The magnitude will be same. While measuring we are considering the two phases which is maximum.
muralykrishna
- Jun 2nd, 2009
The Phase voltage of an generator is 220 - 230 V but the Phase to phase voltage (Line Voltage) will be 400 V. Voltage of R - Phase-230 Y - Phase-230 B - Phase-230 but RY-400V BY-400V ...
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Power Factor
What is the power factor?
bashir varsi
- Jun 14th, 2009
Power factor is the ratio of active power to apperant power. for better energy efficiency it should be unity.
jeet29
- Jun 8th, 2009
Power Factor means that what amount of the power the circuit is using. If the power factor is .807 that means circuit is using 80.7% of power and the remaining 19.3% is returning back to supplying source.
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60Hz Transformer
What would happen if a transformer is made to operate at 60Hz instead of 50Hz ?
expertnayak
- Jun 8th, 2009
In transformer eddy current lossesPe=Kv^2 it is not dependent on frequency so only hyteresis losses will get affectedPh=KfB^x
jeet29
- Jun 8th, 2009
If we are connecting a 50 hz transformer to a 60 hz transformer then there?hystersis and eddy current both losses increases considerably (for detail check effect of frequency on transformer losses).
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Circuit Breaker
Explain what are Single and 2 Pole circuit breaker?
mahmoudp1
- May 1st, 2012
Yes and single pole means that circuit switch two poles / two wires (eg; live and neutral)
3 poles used to switch 3 phase systems
4 poles used to switch 3 phase + neutral wire
5 poles used to switch 3 phase + neutral + ground wire
amolgaonkar
- Dec 9th, 2011
Circuit Breaker is a safety device used to safeguard electrical equipments from heavy current, it trips OFF when more than rated current passes through it.
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Transformer Sound
Why do you get a typical sound when the transformer is put into operation?
nikhilsharma2009
- Sep 15th, 2009
Transformer noise is caused by the phenomenon magnetostriction. When a piece of any magnetic sheet is placed in the magnetic field it gets magnetised and elongate. But when the magnetic field is remov...
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Earthing Resistance
What will be the body impedance of human body>What will be the maximum allowable earthing resistance value?
bkashwin
- Jul 1st, 2010
The resistance of human body is 1000 ohms and allowable resistance is 1000 ohm for some time.
csbalu
- Aug 29th, 2009
Human body impedence depends on the nature of the body and it varies appreciably between different sizes. The fatter the lower resistance.The acceptable earth resistance will be less than 1 Ohm - the lesser the better.
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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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Location of LA (Ligtining arrestor)
Where do we locate lightining arrestor in transmission line?
anupam_srivastav
- Jan 9th, 2010
Ligthing arrestor is mounted on the starting of S/s as well as near T/f for the protection of equipment. Lightining arrestor has nothing to do with lightining it is mounted there from protection from lightining surge. Ci cover & lightining Mast is used for Lightining Attack.
ashok.bhaarath
- Dec 10th, 2009
Ligtining arrestor is placed in Starting of the Substation because of avoiding the over currents &voltages
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Induction Motor and Reactive Power
Does the stator of the Induction machine consume only reactive power? If this is the case, so where does the active power in the rotor come from? Explain.
Nagaraju
- Apr 28th, 2015
What are the effects of motor when reactive power will be low
rajsekhar240
- Dec 2nd, 2009
The stator does not consumes any active power as it is (except we neglect the stator copper losses) it takes the active power and transfers it to the rotor through magnetic field transformation(means ...
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Voltage Source
What would happen if two voltage sources of different magnitude are connect in parallel?
anilsabaji
- Jan 8th, 2010
If the two sources, say batteries with voltages V1 and V2, and internal resistance R1 & R2 are connected in Parallel, then a current equal to to (V1~V2)/(R1+R2) will circulate between them assumin...
nagarjuna227
- Dec 20th, 2009
We cannot find the voltage across two different magnitude voltage sorces.
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Phase Sequence
What happens when we change the phase sequence in 3 phase system?
R Raghavendran
- Feb 26th, 2010
Only the sequence of rotation of Magnetic fields changes, which causes a change in the rotor rotating direction accordingly.
SURAJTHEGREAT
- Feb 22nd, 2010
There is no change for ordinary devices,(behaves same as if the unvaried 3 phase supply is given) The rotation direction of the machines varies with variation in sequence of ac supply..
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Derating factors for Cables Calculation
The cable's actual current rating will usually be lower than the standard (un-derated) value quoted by manufacturer’s brochures. How to find the Derating factors for depth of laying, grouping of cables, etc.
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Direction of Vibration motors
Two electrically operated Vibro Motors are fixed in parallel direction in vibrating feeder. What is the direction of both Vibro Motors?
Padlock
- Jan 11th, 2013
Maybe I wasnt clear on my first answer, if you have two 3 phase vibrators on say a ore feed bin they both operate in different direction ( normally indicated) the wiring connection is different how e...
linu mohan
- Dec 30th, 2012
Both motors direction is same only the counter weight mounted on shaft its angle changes. if opposite direction motor connection done then it will break foundation.
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Spark Plug
When the power supply cable got sparked, it gets burnt or caches fire then explain why the spark plug in our automobiles never get burnt or catch fire even it spark's?
ravs42
- Aug 6th, 2010
Generally in automobiles we have an alternator that produces ample AC supply that is converted to 12V DC supply via the help of rectifiers and regulated IC usage. The 12V is then feed to the batterri...
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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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