Electrical Engineering

this test helps in finding the core losses and copper losses in single test , it is also called as back to back test or heat run test .

You can if done carefully. The neutral of one transformer must be set up to be at the positive voltage of the other transformer. This might require an intermediate step transformer that is center tapped (so three instead of 2 transformers).

Kw x 3412 / 10000 = gpm

I think

Winding copper losses of a transformer can be measured in a short circuit test of a transformer. Impedance voltage is given to the primary and the secondary is often shortcircuited. (some times the reverse is done of this). Full load currents are made to flow in both primary and secondary circuits. This current flow heats up the 2 windings of the transformer. Power consumed at this time gives the transformer copper losses.

No. A fixed resistor cannot be used as a dimmer in a lighting circuit. Depending on the dimming setting, you would need to dissipate substantial power across the resistor. What you need instead is some kind of pulse width modulated device, such as an SCR or TRIAC, or switching power supply, that does not dissipate a lot of power when it is turned on, because it operates in saturated mode, but the average power delivered to the load is what you want it to be.

Generally oil safety switches sense the oil pressure. If there is no preset pressure then the oil safety switch acts (to switch off or cut off the device) For an equipment that needs to be protected against the low oil pressure, such switches are used. when the equipment is standstill (or not running) then the oil pressure is also zero. When the equipment starts running, during the initial few seconds the oil pressure builds up from zero to required pressure. The timer is required not to cut off the equipment control in this initial few seconds. Control system waits for few seconds allowing the pressure to build up and after the preset time, if the pressure does not build up then it switches off the equipment since running the equipment with oil pressure is not good for the equipment.

You do not want equipment to run under its minimum voltage. When that happens many strange things can happen. Immediately comes to mind that motors will burn up do to lack of torque and lack of EMF and just melt down. Electronics can make some very bad decisions when running under-voltage. Flip flops can flop when they should flip and nasty stuff can ensue.

So you want a relay to drop the power off of all circuitry when the voltage is too low for it to operate reliably before something lets out its smoke. And we all know that electronics run on smoke and then the smoke comes out, electronics stop working!

So, low voltage, say bye-bye!

LxW of building x 3 volt amps per sq. foot

Instantaneous over current relay, which operates very fast with no intentional time delay and the operating time of these relay can be as low as 0.01sec . These relay operates only when the impedance between the relay and the source zsis very small compared to the impedance to the impedance of the protected section zl .

Leakage reactance is useful for limiting the short circuit current in transformer and generators. therefore normally the reactance of transformer varies for 4.5% for distribution transformer to 12.5% for 400KV class.

mainly alternator,synchronous motor comes under the synchronous machine.a synchronous motor is not a self starting motor.if a synchronous motor moves with more than synchronous speed then it acts as a synchronous generator.

If the meter is developing more than the necessary forward breakdown voltage of the diode, typically 0.7 volts, then the diode is bad. However, some meters do not generate enough voltage in resistance mode to bias the diode on, unless you flip a switch that enables diode test mode. Use another meter at the same time to measure the voltage across the diode and compare that with the diode's published forward breakdown voltage.

If two waveforms are out of phase by 90 degrees, this is a quarter cycle. If you are looking at a symmetric sine wave that oscillates around zero then one wave will be at its peak value when the other will be at zero crossing point.

zero

In this case, flush means even with. For example an electric box could be mounted on the outside of your wall and would be an eyesore. Flush mounting recesses the box inside the wall and provides a flush mount for the outlet cover plate.

Some more information is needed. 100% power factor for one hour and 220 volts = 22 kva. At 0.85 power factor = 22/0.85 = 25.88 kva

Lattice steel tower consist of:-

1- Main members.

2- Bracing members.

3- Redundant members.

Steel Bracing is the connection between main members of lattice steel tower.

Parallel circuit.

A spike is a sudden rise in current that then goes back to normal. Usually caused by a sudden increase in voltage that could be caused by a lightening strike, for example.

What you are currently working as. Your occupation as in your job or profession.

As the name implies, support wires support the filament wire in the bulb, The filament, of course is the wire that glows white hot, giving out light

B - Dynamic resistance