Electrical Engineering

Kirchoff's Current Law: The current at every point in a series circuit is the same. This can also be expressed as the sum of the currents entering a node is zero. Kirchoff's Voltage Law: The sum of the voltage drops across all elements in a series circuit add up to zero.

there are various types of trasformer tests are here

Open Ckt test

Short ckt test

IR value test

Vector group test

Phase sequence test

Magnetizing test

turn ratio test

T/f oil insulation breakdown test

and so on............

Connect positive to negative, leaving the end positive and negative connections free to power circuits or devices. Connecting batteries in series adds the voltage of the batteries. For instance, connecting three 12v car batteries in series will create a total of 36v, enough for welding.

Direct current (DC) electrical power from a battery has no phase reversal of the electron flow in the electrical circuit. Electrons always flow from the negative terminal to the positive terminal of the battery in the wires of the circuit.

In alternating current (AC), there is a periodic reversal of the flow of electrons (e.g. current) through the wires of the circuit. 60 Hertz refers to the frequency of that reversal of flow. 60 Hz is equal to 60 cycles per second. So AC current from your wall socket in the United States is reversing directions 60 times each second. The cycling is caused by design of the generators used in the power plants that produce the electricity. The current (polarity) reverses direction 120 times each second. Twice in each cycle on a 60 Hz system. Once to the positive and then once to the negative in one cycle.

if you run the unloaded motor at max rpm the centrifugal forces will cause the motor to be totally destroyed

so it is advisable to not to run it at max rpm

it should be okay to run it till 50% of max rpm without loading it

Electric current is the rate of charge flow past a given point in an electric circuit, measured in Coulombs/second which is named Amperes. In most DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm's law. The standard abbreviations for the units are 1 A = 1C/s.

A multimeter device can measure resistance, current, AC/DC voltage, and it also can determine continuity on an electrical circuit, and its range for current, voltage and resistance is widely variable.

Low efficiency

Circuit Breakers and Fuses limit the amount of current flowing through the circuit.

Increase, decrease, or remove the load

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Change the voltage and the current will also change in direct proportion, Ohms law.

This seems like a question from an electrical course, and is probably best answered by your course materials. It's your test question, not ours, and there won't always be someone to ask the answer of. Earn your diploma.

The current is 0. Current is the unit of flow of electrons in a circuit, and in an open circuit, electrons cannot flow. Therefore there is 0 current.

Another way to look at it is that I = V / R, where I = Amps (current), V = voltage, and R = resistance (impedance). In an open circuit, the impedance is infinite, and by using our math skills, we know that X (or V in our case) divided by infinity, is 0.

I = V / Infinity = 0

In a three phase power system, each phase is separated from the others by 120 degrees.

What does the TV's nameplate say? If it says 120v/60Hz it is designed for use on the US/Canada power system, and will only work in countries elsewhere in the world which use that same system. If it says 240v/50Hz it is designed for use on the European power system and will only work in countries elsewhere in the world which use that same system. If it says 120/240v 50/60Hz it can be used on either. Keep in mind as well that if the TV is meant for 50Hz instead of 60Hz, it may be a PAL (European standard) video type instead of NTSC (American standard), so that may be a problem also. <><><> For more information on the different voltages, frequencies and plugs used around the world see the answer to the Related Question shown below and its Related Links .

It's cheaper to put wires in the air than underground, generally. The figure I've heard is it is ~10x more expensive to bury (and get an equivalent - buried conductor must be larger for the same ampacity since cooling is negatively impacted) vs. put wires in the air; this will vary depending on voltage level and loading, obviously.

alternating current is easier to transfer long distances

This varies widely between manufacturers, whether it's a "clear" bulb or a "frosted" bulb, and what type bulb as in incandescent, florescent , quartz, etc etc

You start with a normal one way circuit consisting of a three phase contactor and an three phase overload in series for the forward circuit. Then you add the reverse contactor in parallel with the forward contactor but with line one and line two crossed over i.e. when the reverse contactor is made, line one of the supply will be connected to line two of the motor and line two of the supply to line one of the motor. The control circuit must also be interlocked to prevent forward and reverse being energized at the same time.

Potential difference V = I R. Here I is the current passing through the conductor. R is the resistance of the conductor. In case of good conductor the resistance will be almost zero and so the product too becomes almost zero. Hence the potential difference is neglected.

For an 800 kVA transformer, the size of the fuse depends on the primary and secondary voltage levels. A common rule of thumb is to use a fuse rating of about 125% of the transformer's full-load current. For an 800 kVA transformer at a standard voltage of 480V, this typically results in a fuse size of around 1,200 to 1,500 Amps, but it's essential to consult the manufacturer's specifications and consider local regulations for precise sizing. Always ensure that the fuse is selected based on both the transformer and application requirements.

When looking at voltage numbers the higher the number the higher the voltage. In regards to which voltage is higher the 3.6v (volts) or the7.2v (volts), 7.2 is higher.