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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
Which type of motor is used in heat convector?
The fan in a convector is usually a single-phase induction motor.
What are the advntage of the leading power factor?
A leading power factor means that the current is leading the voltage. That means that in the AC cycle (50 or 60 Hz) the current reaches its peak before the voltage. The amount of phase-lead can be up to 90 degrees which means one quarter cycle, or 5 milliseconds in a 50 Hz system.
How do you calculate full load current for 10000 KVA transformer?
Divide the VA by the voltage. But this transformer is probably a 3-phase one, maybe working on a 11,000 volt system, and in this case the live-to-neutral voltage is 6351 v and each phase supplies 3333 kVA. In this case the current supplied is 3,333,333 / 6351 or 525 amps on each phase. This is a common type of transformer in electricity supply.
Another Answer
Assuming you are talking about the secondary line current of a three-phase transformer, you simply divide the rated apparent power of the transformer by (1.732 x rated secondary line voltage).
Don't confuse line currents with phase currents. Line currents travel in the lines that connect the transformer with the load, whereas phase currents circulate within the windings.
For example, let's assume you have a 10 MVA primary distribution transformer, with a rated secondary line voltage of 11 kV. The full load current would be:
secondary line current = 10 000 000 / (1.732 x 11 000) = 525 A
Do reactive component of impedance dissipate power?
The reactive part dissipates no power because in a reactor the current is 90 degrees out of phase with the voltage.
The effect of this is that any power that leaves the generator on one quarter-cycle comes back to the generator on the next. The net power is zero.
What types of circuit load in which the apparent power is greater than real power?
Apparent power is VA. Real power is W reactive power is VAR. Under an inductive+resistive load the VA is higher than W
What is the output current of a 480 Volt primary 208 volt secondary - 3 phase transformer?
You need to mention the Load connected to find the current.
Why the current coil of wattmeter has more thikness wire than pressure coil?
Current coil carries the current.
Using Ohm's Law (E = I R) Voltage = Current x Resistance or switch around to get R = E / I:
115 volts / 8 Amperes = 14.375 Ohms
The above is correct for DC current but is close enough to be used for AC current.
In a series circuit which quantity remains same throughout the circuit?
Current flow remains the same throughout the circuit.
Why transformer are rated in kVA instead of KW?
Transformers are rated in VA or kVA. That is because the voltage is limited by the power loss in the magnetic core, and the current is limited by the power loss in the resistance of the windings. The rated voltage times the rated current gives the transformer's rating in kVA.
Why fault protection is essential.?
To prevent overheating/damage/fire of the electrical components in a circuit.
What is the function of an electric motor in terms of electric power and motor?
The electric motor changes electric energy into mechanical energy.
Why is there no inductive reactance in DC circuits?
Inductive reactance is a resistance by inductors to the change of current flow, and is dependent on the frequency at which the current oscillates. DC current flows in only one direction so an inductor's impedance remains the same.
What problems can occur with modification or rewiring operations and how can these be overcome?
Rewiring:
1. Obtain the existing documentation, electrical drawing. If you do not have, make one before attempting to rewire.
2. Note down the minute details of the existing drawings, terminal number etc
3. Note down the wire type, sizes.
Carry out the rewiring.
Modification:
1. Obtain the existing documentation, electrical drawing. If you do not have, make one before attempting to rewire. 2. Note down the minute details of the existing drawings, terminal number etc
3. Prepare a modified drawing, with terminal numbers etc.
Carry out modification.
Understand the functionality and ensure you have the same or modified functionality after rewiring or modification. Test the circuit before you hand over to the end user.
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Why does an alternators voltage rise when it is loaded down with a leading load?
Because in the leading load or capacitive load the armature reaction is magnetizing.Here the stator flux adds up rotor flux and so the net flux of alternator increases and the net flux produces alternator's voltage.Hence the alternator's voltage rises.
When power a fan using a simple electric motor the fan's shaft and blades are attached to?
Fans shaft and blades are attached to rotor shaft of the motor
If that is 500VDC, the secondary will have 0VDC.
if that is 500VAC, the secondary will have 250VAC.
How much does it cost to get a replacement stepper motor?
The cost for a replacement stepper motor wil depend greatly on the exact type of motor to be relced. Stpper motors are availbl in 100's of varieties at the low end th cost is $25,but can reach into the thousands.
Where can I find electric motors online?
One online store you can buy electric motors at is "ElectricMotors.com" They have a pretty good range of motors to choose from like jet pump, compressors, conveyors and pool motors.
What does an AC drive do and what is it used in?
A variable-frequency drive (VFD) or adjustable-frequency drive (AFD), variable-voltage/variable-frequency (VVVF) drive, variable speed drive (VSD), AC drive, micro drive or inverter drive is a type of motor drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage.
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3、Wide power design (0.7kW-710kW) and support various motor configurations, Support a variety of encoders, can achieve high-precision closed-loop control.
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What kinds of electronics use a DC power supply?
Almost all digital electronics use a AC to DC power supply. Digital electronics cannot handle AC.
all electronics device having battery powered are using DC power supply http://www.wzmicro.com
