Electrical Engineering

Let R be the resistance, V the voltage, and I the current R = V / I R = 120 / 24 R = 5 ohm

A 2-pole motor has about 1.5 ft-lbs of torque per horsepower where a 4-pole motor has 3 ft-lbs of torque. also the speed of a 2-pole motor is twice that of a 4-pole motor. The speed of a motor is determined by: speed=(120 x freq)/no. of poles At 60 Hz, a 4-pole motor is about 1800 rpm where a 2-pole motor is 3600

The dc tests that can be done on a transformer are to measure the resistance of each windings and to measure the insulation resistance between the windings and between each winding and the transformer case.

All the volt drops across each component in the series circuit will add up to the emf of the battery or power supply. Note the voltage supplying the circuit and divide it by the sum of all the resistances in the circuit. This gives you the current which is the same through all components. Take a component's resistance and multiply by the current and you have the voltage drop across it.

The tarnishing of silver is due to a reaction with hydrogen sulfide. Because the end result of the tarnish is silver sulfide, it is a chemical change.

If you have V = 120Vrms Cos(2*pi*60t + 120). The magnatude of the voltage is 120Vrms. The frequency is 60Hz. The phase shift is 120. That would be the voltage that comes out of a standard American household eletrical outlet. The current would depend on what is plugged into the outlet. A general equation would be VmCos(w*t + theta) or ImCos(w*t + theta) for current. To use a Sine wave, just do a 90 degree phase shift. (sin(t) = cos(t-90) or cos(t) = sin(t+90))

Take it apart and burn the insulation out, if you can, in a pile of brush. Or you could also take a torch to it and see if that gets the insulation out. If you use flame to melt the copper, beware of toxic fumes from burning rubber and plastic insulation.

You can use a multi-meter to measure resistance. The specific portion of the meter for measuring resistance is called an ohmmeter.

This is a 15% overvoltage to the motor, which is generally outside the specifications for a motor spec'd at 208v (typically up to 10% overvoltage is tolerable). Your 240 volt source may be as much as 105% of 240 / 252 volts at times. A buck/boost transformer should be used, unless the motor is designed to be used at 240 volts.

If the gate-channel junction of a JFET was not reverse biased the JFET would just act as a forward biased diode across that junction and the gate would cease to have any control over the channel conductance.

For the same reason in a MOSFET the substrate-source/channel/drain junction must remain reverse biased. The MOSFET could not act as a MOSFET.

no

Primary : 4

Secondary : 3/0

<<>>

To answer this question correctly a voltage must be stated.

Motor efficiency depends on the motor size and how much it is loaded. You get the best efficiency above 75% of the rated load for that motor. Note the table below:

Horsepower Standard Premium Efficiency Efficiency% Efficiency%

1 --- 78.0 --- 82.5

2 --- 78.5 --- 84.0

5 --- 84.0 --- 89.6

10 --- 84.0 --- 91.1

15 --- 87.5 --- 91.7

25 --- 90.2 --- 93.0

50 --- 91.7 --- 94.1

100 --- 91.7 --- 95.0

250 --- 94.1 --- 95.8

it should always be slightly more than 2* length of electrode

GI pire l*b*H should be of (2.5-3)m*60mm*13mm

Horse power (more correctly brake horse power, usually abbreviated to "bhp") is a measure of how fast energy is being used. This is a different concept from amps, which measure electric current, i.e. the "rate" at which electricity flows: to know how much power is being used by an electrical device (light bulb, refrigerator, etc) you need to know the Voltage (220 or 240 V in most parts of the world, but 110 or 115 in some) and multiply this by the current in amps. This gives you the power (in watts, which is the "metric" way of measuring power, as opposed to the British and American way). It is simple to convert watts to bhp (or vice versa), as 1 bhp = 746 Watts (or 0.746 Kw).

Example 1. Your car engine is capable of generating 200 bhp. You could also describe this as being capable of generating 149 Kw (200 x 0.746), and many foreign car manufacturers use this rather than bhp.

Example 2. Suppose you live in a country where the voltage is 240 V, and you have an electric heater which draws 10 amps. Your heater is consuming power (energy) at the rate of 240 x 10 = 2400 watts (i.e. 2.4 Kw). This is 2.4 / 0.746 = 3.2 bhp (but you would be thought very odd to rate an electric heater in this way - the whole world uses the metric system for this!)

In North America the calculations for people in the trade comes from the CEC or NEC electrical code book. The table states what the rating or setting of over current devices for the protection of motor branch circuits should be. If protected by time delay fuses the protection will be 175% of the motors full load amperage. Non time delay fuses the protection will be 300 % of the motors full load amps. The maximum setting time-limit type circuit breaker is to be set at 250% of the motors full load amperage.

Energy and water a closely linked issues. Much energy is used to pump water and if you want to conserve energy, please reduce your consumption of water. For methods and tips on water and energy conservation, check out the link given below http://www.bewaterwise.com/index.html

Induction motors are designed for a certain power. If the power demand is lower than that, you still have to setup the magnetic fields as if you were going to supply that maximum power. As a result, the no-load power factor of an induction motor is quite small, i.e. poor.

The oil is primarily there to carry heat away from the windings but also acts as an insulator.

Its secondary must never be open circuited. If its burden is to be removed, then the secondary must be short circuited first, and removed only after the burden is replaced.

I haven't heard of this in relation to a breaker. Breakers will have ratings for short circuit interrupting, max voltage, line charging, etc. A load break switch will have a "breaking capacity", meaning it can be opened as long as the load current is below the breaking rating.

It is almost inevitable that some energy is lost.If the engine produces heat, as in a gasoline engine, there is a theoretical limit - that of the theoretical Carnot engine - which is itself less than 100%. For example, if the ambient temperature is 300 kelvin and the engine works at 900 kelvin, the theoretical efficiency is 66.666... percent. But the real efficiency would be even less than that.

Current transformer is a device used to measure the flow of current through a power system and the measured current is inputted to a protective relay system. It is used to detect system malfunction.

Current transducer is a device used to measure AC and DC current based on the halt-effect technology.