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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
WHY It is easy to convert an AC to a higher or a lower voltage with transformers?
AC current is constantly alternating between moving back and forwards, this maintains a changing electromagnetic field around it. This principle is used to power a AC transformer, which is made of very simple materials (copper wire and a lil bit of iron usually) and has no moving parts. DC current is moving all in the same direction. This creates a static field as no change is occurring.
Transformers rely heavily on that changing magnetic field to carry out induction and change voltages, DC power was historically put through a commutator or later an Interrupter to create movement in the magnetic field. A commutator is the active element in little electric motors that makes them spin and an interrupter is similar to those old school morse code devices that pulses (switches on and off rapidly) the DC signal to create a field travelling up and down. Once the filed has some movement in it, it was sent into an AC transformer and then converted back.
The process has evolved since then, but is still reliant on a changing magnetic field.
What is under-voltage tripping?
The Voltage of the power supply system is rated at its designed value. If this voltage goes down predetermined set value a under voltage relay can sense the change and then trips off the circuit.
What is earth fault loop impedance?
An earth-fault loop is the path taken by the fault current, when an earth-fault occurs within an electrical installation, and comprises a series circuit made up of
- the utility company tranformer's low-voltage winding,
- the utility company's distribution cable's line conductor,
- the consumer's line conductor to the point of an earth fault,
- the consumer's earthing conductor,
- and the resistance of the earth path back to the transformer.
The combined opposition of this series circuit to the flow of fault current is termed the earth-fault loop impedance, expressed in ohms.
Can you replace a motor capacitor that has a low MFD with one that is a little higher?
You can get away with a 30% or so larger capacitor.
Is it possible to use a dimmer switch to lower the voltage to a power tool?
Though this theoretically could work on a very few power tools, it is NOT a good idea and most likely doing it will only wreck the tool (or the dimmer switch). And why would you want to lower the voltage anyway?
You go to the NEC and look at the chart for developed length and the ambient temperature and the load factor and if it solid or stranded wire as stranded allows for more voltage
What is the function of a capacitor in motor circuit?
Mostly capacitor is used in the induction motors to improve the power factor , and make them to work as a self starting machine.
In the small size , capacity dc motor has capacitor across it to smooth running without spark
How torque is developed due to alignment of two fields?
Torque is developed by, among other things as well, the magnetic attraction or repulsion of two magnetic fields, contributing through rotational leverage to produce a net torque.
What size electric motor will replace a 16 hp gas motor?
Horsepower is horsepower, so a 16 hp electric motor could, on the surface, replace a 16 hp gas motor. Things to consider, however, include RPM and torque.
Gas engines are inefficient, to replace a 16 hp gas engine it would take only a 8 hp electric. standard closest size would be a 10 hp. I have done this several times on air compressors and hydraulic pumps.
Super Position
What is the peak load of a power supply?
A: A power supply when designed it will have some nominal criteria and also some maximum output power available which reflect to the peak load that it can stand without burning up
What is the difference between filter capacitor and bypass capacitors?
Different names for the same thing. Depending on who you're talking to, they may use one or the other. A capacitor can be used to remove high frequency noise (in IC's this is usually switching noise); it can be used to remove low frequency noise also (such as for sound equipment - 60 Hz hum).
Bypass simply means power is being shunted around specific equipment (alternatively, filtering the input to certain equipment).
How must the components be arranged in order for electricity to flow through a circuit?
There must be at least one source of electromagnetic force, or voltage, which is connected through at least one component which uses this voltage, with an unbroken path for conducting the electricity from one terminal of the voltage source through the load and back to the return terminal of the source.
The amount of voltage available from the source must be sufficient to overcome the resistance of the load, aka the voltage sink, and the flow of current will follow a simple formula:
E = I*R, where E stands for the applied voltage, R stands for the internal resistance of the load plus the resistance of the wires between (usually very low) and I is the current which results.
If the circuit is broken, this resistance rises to nearly infinity and so current drops to zero. This is how the switches in your home control the lights.
This is a different matter for A/C since coils and other inductive loads will affect the current.
When Professor Ohm published this law in 1826, his colleagues couldn't believe that the relation was so simple, and hounded him until he retired from the university. Turns out to be a general systems behavior law.
How do you turn a 1964 Lincoln welding machine into a big generator?
It's an engine driven generator like a Ranger, correct? They already come set up to be used as either welding machine or generator when they come from the factory.
How can you increase the torque of an electric motor without increasing the speed?
keep the same winding configuration or number of poles
increase the diameter of the rotor and stator
How do I figure out what size rotary phase converter I need?
To figure out what size rotary phase converter you need to figure out what type of equipment you have, how difficult is to start, and the AMP requirements of it. With this knowledge you can go to any company that sells rotary phase converters and figure out which one you need. http://www.rotaryphaseconverter.info/selectingrightsizerotaryphaseconverter.htm
Describe a double pole single throw relay with a 24 V coil And how does it work?
Double pole single throw relay de-energized, with two separate sets of contacts open. Apply 24 volts to coil terminals, coil steel core magnetizes and pulls hinged armature towards it. The two contacts attached to hinged armature make contact with the two stationary contacts. The double pole relay has now two separate sets of closed contacts.
Assuming the new lamp is in series, the ammeter reading falls because the total resistance has increased. By how much depends on how the lamp resistance depends on voltage. If the lamp is added in parallel to the first, then the ammeter reading doubles.
