Electrical Engineering

25000kv

Current cannot flow through an open circuit.

any one of the three line to neutral is 220 volts

Basic Telephony cable is manufactured with a built in capacitance of 0.084uF (microfarads) per mile on 22-24AWG (for example) wire. Basic cable length can be estimated with a voltmeter. Messuring the amount of voltage discharged when placing the wire to ground, discharging the stored voltage in the wire.

Answer 1: effective voltage is 0.707 * 115 = 81.3 voltage Answer 2 by xfrmrman: 115 VAC refers to rms voltage or effective voltage. VAC, rms and "effective" are all synonymous terms in this case. When you plug your appliance into 115 VAC, it is 115Vrms. The peak voltage, if the waveform is sinusoidal, will be 1.414 x the 115Vrms or the 115/.707 or ~163 volts. Note that the rms to peak factor is the square root of 2 and .707 is 1/square root of 2. This value was calculated for a sinusoid by manipulating udv - (integral of vu') (known as integration by parts) to find the root-mean squared value for heating. An RMS voltage measured across a resistive component can be translated into the rms (heating) current. The "3" in the expression above most likely indicates three-phase sinusoidal voltages (call them A,B, & C) which are represented as voltage vectors phased 120 degrees apart (draw arrows 120 apart originating at the center of a 360 degree circle. Connect the ends to make 3 triangles that when evenly subdivided will create two 60-30-90 (or 1,2 square root of 3 side length triangles) between phases. Each ray out will be the hypotenuse "2" side of the triangle, two "square root of three" length segments will be phase to phase. Divide everything by 2 to normalize the hypotenuse. This means line to line voltage is square root of three x line to neutral voltage. In the three phase case you can have the 115 VAC as your rms voltage and the same peak 163V measured from A to B, B to C, or C to A). However.... Usually the 115 Vrms or 120 Vrms is a broken out 3 phase line to neutral voltage from wye connected windings. The line to line voltage is 115 x square root of 3 or 200 V. For 120 volts, 120 x square root of 3 = 208V. Hence, we see a lot of 208 volt power in industry. Windings can also be connected start to finish for "Delta," but that's another topic.

None. Power factor improvement has no effect whatsoever in saving energy.

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What it can save you is money. A utility company will charge an additional cost on your regular bill for having a low power factor reading less than .92 depending on the type of service. It is billed as a surcharge to the addition cost of the bill. On three phase services this correction can be done by adding capacitance to bring the power factor up to .92.

1. Field Flashing.

2. Resistance of the filed winding should be less than critical field resistance.

3. Speed of the motor should be greater than critical speed.

4. Interchange the field connections.

5. Check the commutator surface and brush.

When assembling a MCC (Motor Control Center) or any other switchgear, the bus bars have to be torqued. The torque specifications are laid out by the manufacturer of the equipment. To find what the specifications are for the specific equipment, you have to find the assembly manual that is shipped with the equipment. Where the bus has been torqued at the factory you will see black marks where the employee has checked each nut that they have done. This is done to verify that none have been missed.

Temperature.

Ohms law is applicable to measure resistance of an element at constant temperature only.

Your question can not be answered as it is.

Reword the question - is it about induction motors or synchronous motors, for example?

Choke coils have a piece of wire wrapped around an iron core and their purpose is to allow a low frequency (typically 60 Hz) to pass, while blocking higher frequencies. Choke coils provide electronic circuits with protection from fast events (like a lightning or similar discharge on the power wires) by acting as a shunt to events whose frequencies are above the intended range.

its vary between 0 t0 1 only .....pf =0.8

If a motor is running when the cap fails it will probably continue to run at much higher amp draw and most likely shut down on thermal overload. It can start with a bad cap, but in my experience it most likey wont.

The output of an AND gate is set only when all of its inputs are set, and when switches are wired together in series, current can flow only when all of the switches are on.

Gain is also taken as Laplace transform of output to Laplace transform of Input . for example voltage gain calculation , it is not necessary to make the energy will be zero in L and C ( if present in the given circuit). But in case of Transfer function to avoid the system dynamics , we have to make the inductor and capacitor energy will be zero as initial condition = 0

you would wire a float switch into the control circuit i.e, the contactor coil (which is relatively low current but rated at least for the control voltage,, in most cases 120VAC). also in the same circuit would be the overload contacts. if the overload trips and/or the float switch opens then voltage is removed from the contactor coil

in elctronic eqiuipments

Yes if you are referring to no real power, no if you are saying no power (real or reactive).

You could have 100A flow from a capacitor bank or inductor bank, which should consume no real power, but provide voltage support / pull down when on line by introducing reactive power to the system.

Fuse is a circuit element which disconnects the electrical current from the mains"supply"

feeding the load when a condition of fault "short circuit " occurs.

one behaviour of electric current that it flows undivided in circuit elements connected

in series and is divided when flows in circuit elements connected in parallel.

so in order to protect a circuit fuse MUST be connected in series to cut/disconnect the faulty current in a safe/short time.

if u connect a fuse in parallel to a component then u will be shorting that component and

the component will not function ;because the fuse is a thin wire with a negligible resistance

and electrical current flows in the most easy "less resistive" component.

besides a short circuit will happen immediatly because u connectthe supply to the neutral!

hope that helps.

There are many types of safety shoes. Most have steel inserts over the toe area and flexible steel insoles to prevent punctures by nails. They may also have metal instep guards. These features protect against smashed toes and feet if a heavy object is dropped, and prevent punctures in the soles of the feet if a sharp object, such as a nail protruding from a piece of lumber, is stepped on.

as it is most affected by arc resistance....

a few may.IF THE PERSON HAS A PROOF AND IF THE FILE IS NOT SURVEY PROTECTED ,IT MIGHT WORK.BUT 95% OF THEM DOESN'T WORK.

W/o power going through, it won't burn out. It may shake itself to bits, corrode, or fail through other mechanical reasons. But burn out require power through it.

yoke is made up of cast iron. if you're talking about inner compartment where the windings stay, then it is made up of silicon steel for max magnetic field distribution