Electrical Engineering

If the fuse thsat has blown is a 3 amp, you should only replace it with a 3 amp fuse, which is good for appliances up to 700 watts (In the UK, on 240 volts). Do not replace a 3 amp fuse with a 13 amp fuse, it gives much less protection. If you replace a 13 amp fuse with a 3 amp fuse, the 3 amp will likely blow, since the 13 amp fuse should be protecting a powerful appliance such as a heater, between 2000 watts and 3000 watts.

A choke is an inductor. For typical power frequency, an inductor will slightly change the power factor, but will not actively use much energy. An abnormal voltage spike on a power supply is equivalent to voltage at a much higher frequency. Inductors appear to be a much greater impedance to high frequencies. This allows the choke to pass "normal" power, while at the same time it blocks "abnormal" power.

A resistor acts independent of frequency. It will limit the effects of the high frequency voltage spikes by dissipating their energy, but it will do the same for the normal power system frequency. In effect, it is always using power, when the choke only uses what you don't want to get to the power supply.

There is no specific ratio, as it depends on the pressure and temperature of the steam.

Steam is merely water vapor, at a temperature above the boiling point of water (212 degrees F., 100 degrees C.). When water boils, and turns to steam, the steam will occupy a volume 1846 times that of the water that was converted -- at atmospheric pressure, and at the boiling point of water.

Such steam is useful in cooking, for example, to steam vegetables. But in general, it is not very useful at this low pressure. Steam used in industrial processes or to drive engines or turbines, is at much higher pressures. Those pressures are obtained by vaporizing water in a closed vessel, so that the steam is allowed to occupy a volume much less than the 1846 times ratio just noted.

Steam in closed vessels can build up to enormous pressures, which ultimately can rupture the vessel. Fragments ejected as shrapnel from such an explosion can have more striking power than a bullet or a cannon shell. Perhaps worse, the released steam contains enormous energy, which can for example scald a human to death almost instantly.

For that reason, steam generators are provided with valves which release the steam when a desired pressure is reached. They are provided also with blowoff valves, which open at a somewhat higher pressure, in the event that the orifice or pipe through which steam is withdrawn may not be of sufficient size. Such blowoff valves vent the steam chamber into the atmosphere, or into a condensation chamber. The steam vessels are designed to withstand a pressure usually twice or more the level of pressure that triggers the blowoff valve; this is a safety measure.

Because the ratio of water to steam varies, according to pressure and temperature of the steam (and whether it is "wet" steam or "dry" steam), it is more common to speak of pounds of steam. This is the weight of the water converted into steam (of the desired pressure and temperature) in a given time, such as pounds per hour. Water, as you may know, weighs 8.33 pounds per gallon.

Knowing the weight of the steam is important, for example in running a steam turbine. The weight of the steam, and its velocity, determine the momentum of the steam; and that can be translated into the force or torque applied to the turbine rotor, thus the output of the turbine. That in turn translates into how many kw. of electricity the turbine-generator can produce per hour. Such computations actually get pretty complicated, but you can see that there is a relationship between the amount of water converted into steam, and the output of an engine or turbine or generator which is driven by that steam.

There is a specific field of engineering (and physics) which deals with steam. It is called Thermodynamics, It is essential in designing steam boilers and steam-powered equipment.

Hydroelectric energy uses the potential energy of a mass of water in a high reservoir, that is released by running the water down pipes so that it gathers speed and eventually hits turbine blades to rotate a shaft that turns an electric generator.

The potential energy of the water comes from the Sun, which evaporated the water from the sea or other place and deposited it at a high level via rain on the upper part of the mountain.

read the boring science book

Michael Faraday <3

A wattmeter is an instrument that measures the electric power of a circuit, in watts. A watt meter is installed in almost every house, and is used to determine a family's monthly electric bill.

Because the transformer designer does not know the power factors of the different loads that might be connected to it. The way round this probem is to specify the voltage and the maximum current that the transformer can supply, then multply them together and print the VA, kVA or MVA rating on the transformer. Then it's up to the user to comply with this rating to avoid damaging the transformer.

circuit breakers are switches that open quickly usually opening with a fault condition

air circuit breakers need a long path to quench the arc

oil filled circuit breakers quench arcs much more effectively and in a smaller space

vacuum breakers have no media for an arc to propagate and are far smaller

fuses generally are filled with silica sand to quench the arc

and higher currents make the arc path much longer

typical AIC

fuses 200,000A

air breakers 15,000A

oil breakers 50,000A

vacuum breakers 100,000A

fuses work once and work correctly and dont fail or weld closed

they are inexpensive and safe

breakers can work tens of times

breakers need rework and recalibration whenever they are reset

breakers have mechanical moving parts tempered springs and require periodic maintenance and testing

Breakers can weld shut with a short

You have to measure the voltage, and the current. The resistance is then calculated by using Ohm's Law.

Commutator is a device in a motor through which supply is fed.

Yes provided the AC drive can take load of two motors. But this is not very ideal nor good

Sizing circuit breakers for motors falls into a different category. Because of the inrush of current when the motor is in the stopped position, the breaker has to be sized to allow for this. Breakers usually are 250% of the nameplate full load amp rating. The wires that feed the motor are sized to 125% of the full load amps of the motor.

DC transmission lines are only used in special applications for example very long distances or for connecting two non-synchronous power systems. As an example UK and France are connected by DC power cables because the two power systems are not synchronised.

The power factor (cosine of phase angle) of pure inductor is zero because the phase angle between current and voltage is 90 degrees .If the value is substituted in the formula It will be zero.

In general, no don't try it. The result will either be damage (e.g. overloaded motor burnout) to the appliance or a severe reduction (e.g. an electric heater giving off only 1/4th its rated heat) in its performance.

There actually is no such thing as 2 phase. You either have single phase (As most/all residential services), or three phase (primarily in commercial/industrial). When a normal three phase motor 'loses a phase' (blown fuses, open winding, bad contactor, etc...) if it continues to operate, it is considered 'single phasing'. While such operation is typically only briefly. (They usually don't run long) While it probably will not operate very long, the motor would over heat, and loose speed rapidly, and they will sometimes make noise. If you need to operate a three phase motor on residential service, you will need a 'three phase converter' (some people call them 'inverter's) to electronically convert single phase power into three phase, but they are usually only practical for smaller three phase motors.

The question is not worded correctly. It should ask, what is the full load current for a 5 hp motor.

The correct answer is predicated on a few unknown factors.

#1. What is the user voltage?

#2. Is this a single phase or a three phase application?

Without those unknown values here is the N.E.C. Table "nominal" Ful Load Currents.

3 Phase: 230V = 15.2A 460V = 7.6A

1 Phase: 115V = 56A 230V = 28A

Keep in mind that the N.E.C. Tables are for nominal applications only. The National Electrical Code requires that you refer to the motor nameplate specifications for applying both short circuit and overload protection.