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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
Would a DC motor turn if only the armature were supplied DC voltage?
if there are magnets on the stator
and the commutator is phased properly
this is known as a permanent magnet dc motor
the starting torque is dependent on armature current and the strength of the magnet
the speed is directly proportional to the armature voltage
a shunt motor needs the field energized for starting.
more field more starting torque
What size generator do you need to move a 30 hp electric motor?
A 5 kW generator would turn it over but if the full 30 hp of mechanical power is needed, that would require about 30 kW of electric power from the generator.
How do you reverse a direction of a slip ring motor?
It is very simple. Just interchange any two phase wires.
i.e.
Y and B
( or )
R and B
( or )
R and Y
for example Stop the supply. keep R phase wire as it is and disconnect B phase wire and Y phase wire. Connect B phase wire to the Y phase motor stud and Y phase wire to the B phase motor stud. Now give the supply, now motor revolves in opposite direction to the earlier.
pcc is the power control center, in which all distribution switches are installed and operated here
How you understand which side of a transformer is high voltage side and low voltage side?
at high voltage side, current is low. hence the size of conductors is reduced or small.
At low voltage side, current is high. Hence the size of conductors is large.
Mutual (not 'matual') induction occurs when a changing current in one circuit induces a voltage into a second circuit. An example of mutual induction is a transformer.
How do compute the reactance in an inductive circuit?
Inductive reactance, XL, in ohms, is given by:
XL = 2 pi f L
where:
f = frequency (Hz)
L = inductance (H)
What determines the voltage in a generator?
in generator the flux will determines the voltage. the flux will improve by auto voltage controller or any other equipment.
What is the ratio between locked rotor current and full load current?
Each motor has a published manufacturer Lock Rotor Amperage (LRA) rating that is used to obtain this ratio. If a manufacturer otained a reading of 100A while bench testing their motor (equipment) at full load, if the motor FLA (Full Load Anps) is 50 amps, the raito LRA to FLA is 2 to 1 or 200%.
What is the resistance of a clothes iron that draws a current of 12A at 120V?
By Ohm's Law Voltage = Current x Resistance
R = V / I = 120 / 12 = 10 Ohms
Leading angle means that the current lead voltage by 90 degree,which implies a capacitve load. while,lagging angle mean when the current lag the voltage by 90 degree or when the voltage lead the current by 90 degree.which implies an inductive load.
Does voltage flow through a circuit or is voltage establish across a circuit?
voltage does not flow, current flows
Answer'Voltage' is another word for 'potential difference' -you can think of it as being the equivalent of the difference in pressure across, say, the input and output ports of a central heating radiator which is responsible for pushing water to flow through that radiator. So 'voltage' exists across two points in a circuit, causing current to flow through the conductor between those two points.
What is the voltage drop in diode IN4007?
forward drop is the same as any other silicon diode, about 0.7V
Why does amplifier gain reduce?
Since we know that the amplifier gain is given by
A=Output voltage/input voltage (where A is the amplifier gain)
So, it can be written as output voltage=A*input voltage,
so when the output part increases gain increases but when input part increases gain decreases
Is oil in transformer use for lubrication?
Transformer oil is for cooling.
Transformer oil has heat conductive properties, along with its insulating properties, that take the heat build up from the windings to the outer case of the transformer. The transformer tank is used as a heat sink to allow the outside ambient temperature to cool it down. On big kVA transformers there are heat tubes on the outside of the tank. On even bigger transformers there are fins that the oil travels through. This provides a bigger surface area to dissipate the heat. The tubes and fins also allow thermal siphon of the oil through the tubes by drawing in the cooler oil at the bottom of the tank and moving it to the top of the tank where the hotter oil is. This circulation greatly increases the cooling ability of the oil to keep the transformer with in its allowable temperature rate of rise zone.
Additional AnswerThe second function of transformer oil is insulation. Oil has a far greater dielectric strength than air, so it enables internal components at different potentials to be located far closer together -thus significantly reducing the 'footprint' of a transformer.
Why is armature connected to a sprinngy steel strip?
In an electric bell, a flat steel spring brings the armature back to its original position.
Is the resistance in the start winding greater or less than the resistance in the run winding?
The resistance in the start winding is greater because it is longer and thinner and has the greatest resistance to current flow
How do you check number of poles on a three phase induction motor?
Name plate data should indicate the number of poles / RPM.
For speed N= (120 x Frequency) / Number of poles Using this formula you can find out the number of poles, provided you have other parameters available.
If no data is available, run the motor on no load, and measure the rpm, know the frequency, calculate the poles.
How the severity of an electric shock depends on the current and voltage?
he severity of injury from electrical shock depends on the amount of electrical amperage (current) and the length of time the current passes through the body For example, 1/10 of an ampere (amp) of electricity going through the body for just 2 seconds is enough to cause death.
