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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
How can makeup effect your skin?
It can cause nasty breakouts. and seriously clog your pores but that doesn't mean don't use it just clean your face after
Is thermal energy a non conventional source of energy?
This is difficult to decide I think. It has been available for 50 years now - does that make it conventional? It is a well established and reliable energy source.
What is different Circuit Breker And Isolater?
I think that the questioner is asking what is the difference between an isolator and a circuit breaker.
A circuit breaker is a switching device designed to interrupt a fault current.
An isolator is not intended to break a live circuit but, rather, to provide a visible separation between a circuit component and live conductors.
For example, isolators (or 'disconnectors' in US parlance) are located on either side of a high-voltage circuit breaker. If the circuit breaker requires maintenance, then the procedure is to:
a. trip the circuit breaker.
b. open the isolators on each side of the circuit breaker, so there is a visible gap between the circuit breaker and the 'hot' conductors.
c. apply temporary earths (grounds) between each isolator and the circuit breaker.
d. complete a 'permit to work' card.
e. begin work.
There are different types of megger, which is simply a trade name for a range of different instruments. Not all meggers use d.c., for example, an earth-resistance megger uses a.c. On the other hand, an insulation-resistance megger uses d.c. because it applies a constant test voltage across the insulation being tested.
What is the cable size for a 2HP pump?
Apart from anything else, it's necessary to know the rated votage of the pump!
A; fluorescent lamps needs 500 v to start once started the voltage drops to ~90 v the starter perform the kicking to get to 500 volts without it it will not start so taking it out after it started that is when it is not longer needed
nit trichy is the good one , to my knowledge..
if opting for M.tech In CSE.. nit calicut, nit hamirpur and nit surathkal are also good
What motor gets more heated single phase or three phase?
Your question is a little like asking, 'How long is a piece of string?'! Do the two motors have the same power rating, or are they different?
The rate at which energy is used by any machine is defined by its power rating. If the power ratings of two different machines are the same, then both machines use energy at the same rate. So if a single-phase motor has the same power rating as a three-phase motor, then they will both use exactly the same amount of energy over a given period of time.
So, if a single-phase motor has a greater power rating than a three-phase motor, then the single-phase motor will the greater amount of energy in a given period. On the other hand, if a three-phase motor has a greater power rating than a single-phase motor, then the three-phase motor will the greater amount of energy in a given period.
How could you reverse the rotation of the motor?
The motor will spin the direction that the positive lead is on. So if the shaft is pointing towards you, you will need to put the positive lead on the left side to make it turn counter clockwise.
Can a 380volt's 3 phase motor can be converted to 230volt's three phase motor?
Only if you want to damage it.
"277" Volt 3-phase will usually mean 277 from each phase to neutral, and 480 from phase to phase.
By "230 3-phase", you likely mean 120 phase-to-neutral, and 208 phase-to-phase.
If you really mean 230, then you are probably NOT talking about a three phase motor.
Do voltages vary around the circuit and why?
A: Voltages varies on a circuit because current varies caused by difference in resistance
What are the applications of jfet transistor?
The Junction Field Effect Transistor (JFET)exhibits characteristics which often make it more suited to a particular application than the bipolar transistor. Some of these applications are:
- High Input Impedance Amplifier
- Low-Noise Amplifier
- Differential Amplifier
- Constant Current Source
- Analogue Switch or Gate
- Voltage Controlled Resistor
What is voltage potential betweei positive to earth?
By saying 'positive', you appear to be describing a d.c. system. In which case it depends entirely on the potential difference of the source and how it is earthed. If you are describing an a.c. system, then you presumably mean 'line', rather than 'positive', then -again- it depends on the potential difference of the source and how it is earthed -e.g. in the UK, the potential of the line, measured with respect to earth, should be close to the nominal value of 230 V.
Incidentally, there is no such thing as 'voltage potential'. 'Voltage' is synonymous with 'potential difference', not'potential'. So, when you say 'voltage potential', it's the same as saying 'potential difference potential' which, I think you will agree, doesn't make any sense!
Why emitter base junction is always forward biased for normal operation of transistor?
The easy answer - it's not always forward biased. Both it, and the collector-base junction, must be forward biased to pass current through to the collector. Whether NPN or PNP the relative bias (voltage) on the base determines the conduction from emitter to collector. NPN: if the base is positive, relative to the collector and emmiter, the transistor conducts. PNP: if the base is negative, relative to the collector and emmitter, it conducts.
For either transistor arrangement, draw two diodes connected either by their anodes or by their cathodes. The base is the region between them. In an NPN, a positive voltage on the anode, compared the to the cathode(s), will forward bias both, allowing current to flow. The same applies to a PNP with a relative negative voltage being the 'switch', turning both on.
bob
02/07/2009
The first paragraph is incorrect. The collector-base junction will be reverse biased for normal operation. The only time an NPN base will be biased more positively than the collector is when it's operating in saturation mode.
The second paragraph is also misleading. It implies that current flows (for NPN) from the collector to the base and then from the base to the emitter. Emitter current is base current plus collector current. The collector-base junction is normally reverse biased, so little current would flow.
Here's a link with relevant info: http://www.nationmaster.com/encyclopedia/Bipolar-junction-transistors
Dennis
How do we adjust the voltage of a shunt generator?
The voltage is adjusted with a potentiometer that adjusts the field voltage through the voltage regulator.
What are advantages of high power factor?
Power factor ranges from zero to a maximum of 1. At 1 the current and voltage waveforms are in phase and operate at maximum efficiency.
What measurement can vary with AC current by not DC current?
HZ.
Hertz is the name given to the frequency of the alternating circuit.
Direct current (DC) has no frequency since one wire is always positive and the other is always negative; but AC (Alternating Current) rapidly changes polarity, and does so at a rate that is defined by HZ.
How you determine the starting and running winding of a capacitor start single phase motor?
I think the resistance value of starting winding is less than the running winding of the single phase motor
How do you run 220v 3 phase motor on 575v?
First of all, your power source must be 3-phase if you want to run the motor, then you need a step-down 3-phase transformer to give 220v 3-phase output.
How is an electromagnet used in the motor of a cooling fan?
the north and south p[oles repel to make the motor turn the north and south p[oles repel to make the motor turn the north and south p[oles repel to make the motor turn
How does a three phase voltages is generate?
The power circuit is only active between two phases - the live and neutral. Thwe third phase (Earth) is simply a safety device designed to blow a fuse in case of short-circuit. The power is delivered down the live wire, and returned by the neutral to complete the circuit.
What operating condition is most likely to overheat a motor?
When dc motor run full torque at low speed. Armature current is high and field current is set to max to get the torque. When motor is field weaken then temperature decrease at same cooling air flow
How do you calculate mcb rating?
Circuit breakers are used to protect the conductor that is connected to it. The sizing of the conductor is based on the current of the load. As the connected load current is increased so must the wire size to accommodate that higher current. Therefore as the wire size increases so must the breaker size to accommodate the higher load current.
