Electrical Engineering

10 ohms or less is considered a good earth ground reference. The lower, the better.

Because they are silicon controlled rectifiers, in other words a diode you can turn on (you can't turn them off, this happens when the voltage passes through zero). Therefore if you only use one you would end up with half wave a.c. This means you can't reach full power. Using a second one to control the other half of the cycle solves this problem. This is why the Triac came to be, it is really two thyristors in one package. Two thyristors are also used in D.C. Controls too, to turn off the main thyristor the second one dumps the voltage into a capacitor allowing the main thyristor to unlatch.

Information is incomplete. You need to know the load in Watt or Kilowatt and the voltage on the secondary side to determine the load current, on which the size of the wire is designed.

A balanced bridge has zero volts across the two test nodes, while an unbalanced bridge has non zero volts.

Totally enclosed fan cooled motors are more adaptable to outdoor and high moisture areas and with a bit of caution, they will work well.

Dry transformers are used in industrial and commercial sites where the supply voltage three phase and in the range of 480 or 575 volts. The dry core transformer's primary is two legs of the three phase system and the secondary is, in North America, 120/240 volts. The lower voltages are distributed by a load center to power lights and receptacles for offices and small appliances and equipment.

In a DC circuit Power (P) in watts is equal to Voltage (E) times Current (I).

1000 Watt = 1 kW

P = EI thus I= P/E

For kW then I = (P x 1000)/E

Example with Power of 2 kW and Voltage of 250 V DC:

I = (2000/250) = 8 Amp

The 5 Ohm resistor will have more current passing through it than the 10 ohm resistor. Since the resistors are in parallel the Voltage across each resistor is the same.

Power or the amount of heat in terms of the question can be derived from Power = Voltage * Current.

Ohm's law tells us that the current flowing through a resistor is equal to the Voltage across the resistor divided by the resistance. The formula for power is then the Voltage * Voltage / Resistance.

Since V^2 / 10 is smaller than V^2 / 5 we know that the 5 ohm resistor will always have more power dissipated than the 10 ohm resistor.

I was on the second wave of AC-119K to Vietnam (Nov 1969). I later was stationed at Udorn Thani in the spring of 1970. I was part of the move from Udorn to NKP. This was late in my hitch, so it was sometime late summer/early fall 1970. I left SEA November of 1970 never to return. Can't say how long they were stationed there.

No. With the values given the motor will run at 1500 RPM. RPM = Hz x 60 x 2/# of poles. The only way the motor can be run at that speed is by using a VFD as its source of power.

Yes, the code requires a complete dead front so that no access can be made to the bare distribution bus behind the panel face.

A motor that is rated at 250 full load amps will need 400 amp time delay fuses or a 500 amp frame breaker with adjustable amperage trips. The wire size for this motor has to be 125% of the motors FLA. 250 x 125% = 312 amps. A 350 MCM copper conductor with an insulation factor of 90 degrees C is rated at 325 amps.

On a 230 v supply assuming a volt-drop of 5% that is 11.5 v, so the maximum cable resistance is 11.5 / 40 in ohms, 0.2875 ohms so for 1000 metres of cable in total you need a cable that has 0.0002875 ohms of resistance per metre.

Copper with a cross-section of 1 mm2 has resistance of 0.0168 ohms per metre so the size of cable needed is 0.0168 / 0.0002875 mm2, which is 58.43 mm2, so a cable of 60 mm2 should be selected.

Oil is used in transformers to insulate and cool the windings.since heat reduces the efficiency of every electrical machine, oil is used in transformer for example to cool and maintain the efficiency level of the transformer .

The voltage induced into the secondary winding will be lower than the voltage applied to the primary winding. The primary winding being the winding connected to the supply, while the secondary winding is the one connected to the load.

You multiply it by 4.47=x

The breakdown voltage test is used to evaluate the degree of impurity in insulating oils due to foreign particles, gas and water. It meets current regulations and is economically useful to protect electrical systems such as transformers and switches, as well as, medical and security systems from breakdowns. The main reason for such damage is the poor condition of the insulating oil.

The oil tester is designed for continuous operation in the laboratory. This high performance instrument is characterized by the combination of extraordinary properties such as a test voltage up to 100 kV, clear breakdown detection and absolutely reliable measurement results. The TOP oil tester is the leading testing instrument for users in the electricity industry, in testing institutes and other industrial applications.

dc motors generate more noise.

Any controller used in motors or electrical drives are only to get variable speed or variable torque or to get higher efficiency.

The controller can be anything, it might be micro controller or it can be DSP controller or may be other.

But DSP controller finds some advantages over micro controller.

Both the controllers are Digital controllers only, but DSP controller has inbuilt Analog to Digital converter, inbuilt Digital to analog converter , inbuilt counter and inbuilt pulse generator.

With a micro controller we need to assemble all the above converters, counters and pulse generators externally, so DSP based electrical drives are more popular though the cost is more compared to micro controllers.

In my experiences with armored cables such as MC,HCFC the bending radius of the conductor inside is much smaller than the radius you could bend the armored casing. in other words the clad casing is going to break Which could potentially damage the conductors inside and should not be used. As always electrical wiring is not a hobby and should be left to licensed electricians who follow NEC codes and local codes

Probably not. The single phase three horse power motor will be much larger in physical size than its three phase counterpart, and will probably not fit.

He Works for a compony called la la la la lo po

the most basic transformers have at least two coils, a primary and a secondary. A transformers nameplate will provide you with the max allowed voltage and current, as well as a voltage per turn ratio. for example a step down transformer could have a primary of 120 volts and a secondary of 24 volts this would give you a ratio of 5:1.

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