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PID control
Give brief detail on PID Control.
SURAJTHEGREAT
- Mar 3rd, 2009
A controller is a device employed to obtain a stable output. There are many controllers of that PID controller is the most widely used. A proportionalintegralderivative controller (PID...
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Wattmeter reading
Why does wattmeter's reading go negative?
bittu123
- Nov 9th, 2011
Suppose, phase difference between V and I is "A"(angle). and wattmeter reads +ve. Now if phase difference became (A+180), wattmeter will read -ve of same magnitude.
It simply means, direction of power flow gets changed just because of changing in direction of either current or voltageSURAJTHEGREAT
- Mar 3rd, 2009
If you have seen the wattmeter ratings, it will be (300V,10A,UPF) (Voltage, Current, Power Factor) That is wattmeter needs voltage and current to measure power. So a wattmeter consists of t...
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Current Transmission
Why is alternating current used for transmission?
bonanova
- Mar 6th, 2009
To reduce I-squared x R loss, transmission is done at voltages much higher than what is usable by consumers. Transformers can easily raise AC voltage for transmission and then lower it for consumption. The same cannot be done for DC power.
Nwannaa
- Jan 22nd, 2009
Alternating current is used for transmission because it is easier to transmit AC over high distance at high Voltage levels.It is also more flexible to handle AC at different levels of transformation t...
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What is a DSM(Demand Side Management)?.
engineerfaisal
- Mar 20th, 2009
Demand-side management (DSM) programs consist of the planning, implementing, and monitoring activities of electric utilities that are designed to encourage consumers to modify their level and pattern of electricity usage.
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Tripper Drops
Consider you have a tripper at your house. The instant you switch on your motor, the tripper drops. What could be the problem?
mallick.subratkumar
- Mar 20th, 2009
The tripper drops because the motor is an pure inductive load & when we switch ON it, as the properties of inductive load define it oppose sudden change in current so the tripper drops when motor switch is ON.
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Synchronous Generator
How and when synchronous generator acts as a synchronous condenser?
mallick.subratkumar
- Mar 20th, 2009
When synchronous generator is over exited by connecting an induction motor parallel to it, the generator gives a leading power factor which act as asynchrous condenser, it used where most of load are pure inductive (like motor).
vishweswarrao
- Mar 11th, 2009
Whenever synchronous motor is operating under over excitation it acts as synchronous condensor. This mode of operations are used for improving power factor.
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Wattmeter
Wattmeter has two coils in it-the current coil & pressure coil, why is the pressure coil so named? How is the power being measured by the Wattmeter?
mallick.subratkumar
- Mar 21st, 2009
Current coil means it measure current of circuit & pressure coil means it measure voltage, when current coil is connected series, pressure coil connected parallel in one circuit ,as P=V*I*cos?,
So we have V, I, & ?=[1/tan(V/I)],
Now the power is being measured. -
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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Voltmeter Measurement
If we connect a voltmeter between earth and ground wire, how much it will measure?
bittu123
- Nov 9th, 2011
there is no difference bet earth wire and ground wire, both are same thing. BUT, if U mean earth as soil (i will refer soil as earth), and U disconnected ground wire from soil and put a voltmeter in ...
p2atik
- May 16th, 2009
Since the earth and ground wires are at same potential there will be no potential displayed in the voltmeter,But on the contrary volts?may be displayed between the?NEUTRAL and the ground/earth wire.
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Conductor Size of Fuse and Cable
For 63A load we can use 25/35sqmm cable. For same rating fuse conductor size is too low. How is it possible?(Its not depends on meterial, because single strand for above cable size is enough for fuse)
haveasafeday
- Mar 24th, 2009
Generally Fuse is used for short circuit protection. That means it should be higher(normally 2 to 3 times of rated current depending on design) than other installation in a perticular circuit.
sindhejs
- Feb 16th, 2009
As we know that fuse use for the safety purpose. And current will flow on the bases of resistance, as fuse?wire of small length (so it has lesser resistance), it can withstand 63A (as 25/35sq. mm cab...
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Lightening Arrestor
Location of lighting arrestor should be near transformer or not? Why?
mallick.subratkumar
- Mar 30th, 2009
Yes it must be near to the transformer,because when there is a lightening occurs the total power must go through Lightening Arrestor to ground with out damaging the transformer.
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Sub-Station Label
Why the Substaions are labled as 11KV/33KV or 66/11KV etc instead of label with the POWER TRANSFORMERS Rating (In MVA/KVA)?
kannanvellai
- Mar 31st, 2009
All electrical equipments operated depend on voltage.In substations we can get same ratio transformers with various power ratings.Ex:400/200KV with 800MVA 315 MVAPower rat...
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Power Factor
Why the Voltage rises when Leading Power Factor is occurs?
shobhit bansal
- Apr 3rd, 2009
When there is a case of leading power factor, that means synchronous generator works in over excitation mode, reactive power will be generated, and as we know that change in voltage is directly prop...
SURAJTHEGREAT
- Mar 18th, 2009
We know flux is 90 degree ahead of voltage...If leading p.f. load is connected,the armature flux and main flux aid each other,Bcoz current(field current=flux)is 90 degree ahead of voltage. (Thus 2 fluxes aid each other)and since voltage propotional to flux,voltage increases..
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Current Circulation
Is it possible if their is no voltage then their is no current circulation or does it depend on circuit condition?
manojprabu
- Apr 4th, 2009
You are right without voltage their is no current circulation in any circuit (EMF is electro motivate forces is the force that produces movement of electrons in circuit if it is closed)Voltage is the major source of current.
arun uday rana
- Aug 2nd, 2008
Current is nothing but flow of charge inside the conductor. It is always true that any fluid or gas always flow from higher pressure to lower pressure (or temp.). It is same in the case of charged p...
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Phase Shifting
Why do we use phase shifting at Current Transformer?
raul10
- Apr 8th, 2009
We use phase shifting in current transformer to transfer the magnetic flux density around the core
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APFC/Capacitors in DC circuit
Why many people do not connect the APFC/Capacitors in DC circuit?
KKMSURESH
- Apr 8th, 2009
APFC means Automatic Power Factor Controller. Power Factor is applicable only in an AC Supply, DC is one of direct current, there is no Power Factor in DC Supply.
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Three Phase Induction Motors
Why capacitors are not used in 3 phase induction motors?
mohann2008
- Apr 11th, 2009
In three phase induction motors, capacitors are not needed, because when the current passes through? three wires, three magnetic fields will be produced. Due to the interaction between those magnetic fields, RMF will be produced automatically without the help of capacitors.
naresh20047038
- Mar 20th, 2009
In 3 phase Induction motors rotating magnetic field will be created which in turn interacts with the rotor conductors resulting in rotation of rotor, so there is no need of capacitors for starting pur...
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Pure Sine Wave Inverter
What are the applications of pure sine wave inverter?
engineerfaisal
- Apr 13th, 2009
Pure Sine Wave Inverters will: Allow inductive loads like microwave oven and motor driven products to run faster, quieter and cooler. Reduce or eliminate audible and electrical noise in fans, flo...
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