Electrical Engineering

Short circuit voltage is the voltage that has to be applied to the primaries of a transformer, so that the nominal current flows through the secondaries, when they are shorted. This value is important, if transformer secondaries shall be used in parallel. Ideally all transformers with parallel secondaries should have the same short circuit voltage. When their short circuit voltages are different, the transformer with the lower short circuit voltage will be loaded more than their relationship of power ratings would predict. The short circuit voltage is also important in the design of a transformer, because it predicts, how much the secondary voltage will drop at nominal output current. This knowledge helps the designer to find out, how many further windings the secondary needs for a certain voltage in relation to an ideal transformer. Short circuit voltage is also known as impedance voltage.

none the energy is in the amps

The milli-amp-hours rating has nothing to do with the voltage. The rating should be something like 3000 mah at 12V or 3000 mah at 1.5V.

One common 3000 mAh battery is 3.0 volts; another is 3.7 volts. A common camcorder battery is 7.4 volts. Some DeWalt tools use 12 V 3000 mAh batteries.

The load current is made to flow through the thermal overload relay, which is actually a bimetalic strip. Beyond a prespecified current the bimetalic strip tend to deflect due to heat (thermal effect) thus cutting off the circuit and hence it acts as an over load relay protection.

When a dc supply is connected to a resistor, current flows.

The current in amps is equal to the supply voltage divided by the resistance in ohms.

The power used is the voltage times the current, and that appears as heat in the resistor, which might become hot to touch.

A transformer that increases voltage is a step-up transformer.

If the fan motor says 220 230 240 they will all work on those voltages The rating are important The higher the voltage, the amps will be lower=cheaper to run Same goes for frequency( hz ) the higher number runs faster U can use a higher rated hz on a lower hz it will run slower than normal U cannot always do the reverse especially dealing with hz and voltage Your application will work safely but look at motor nameplate it might be rated for multiple voltages and frequencies Also the motor will detriorate a little bit faster when u use 230v on something designed for excalty 220v but this is still safe

The most obvious difference is their purpose. A CT is used to provide power system measurements to instrumentation - such as relays and metering equipment. These are typically designed to provide 1-5 amps in their secondary sides. A distribution transformer is used to provide power to costumers. These are designed to provide much higher current.

CT's are designed to give a ratio of the primary current to the secondary - not specifically the same voltage. Due to this the voltage on the secondary side will vary depending on load (from a few volts to saturation level voltages). Distribution transformers provide a constant voltage at a varying current level.

there are other differences as well - size, insulation, primary connection, etc.

An 'ohmic' resistor is one which obeys Ohm's Law. For Ohm's Law to apply, the resistance of a circuit must be constant over the range of incremental voltages applied to it. If the resistance changes over an incremental range of voltages, then it is said to be 'non-ohmic', and it does not obey Ohm's Law.

secret.........

They are proportional..

induction motors have very little starting torque

as the motor come up to speed it reduces the torque load until it gets near synchronous speed

A rectifier converts from AC to DC power by blocking one half of the AC current. A full-wave bridge rectifier is actually 4 rectifiers combined in such a way that it reverses the blocked half of the power, allowing it to flow through.

A standard power supply consists of a transformer (for voltage changes), a rectifier, and additional components for cleaner power (e.g., filters to smooth out the waves of AC power, voltage regulator, etc.).

100meter

A 'polarity test', as it applies to a switch, is performed to confirm that the switch is located in the line conductor and not in the neutral conductor.

critical.

Power Factor measures the difference in phase between the current and voltage. When they are in phase the Power Factor is defined as 1. When out of phase the value is less than 1. If they are 180 degrees out of phase the Power Factor will be zero.

1.) Turn all the power in the circuit off. 2.) In volts mode (both AC and DC) check to make sure there is no power. 3.) In ohms mode check to see if the resistance is close to zero. (Check zero by connecting the leads together momentarily.) Note that light bulbs will have far less resistance cold than when hot, due to their negative temperature coefficient, so you should remove them, and that transformers and motors will appear to have zero ohms due to their inductive reactance, so they will also need to be pulled from the circuit.

series circuit

Three phase ovens are made for home use. It is important however to know if the home is wired for three phase or for single phase.

The high leg is a byproduct of another feature. It is not in and of itself useful. On a three phase delta transformer, one of the three windings (only one) is center tapped to create a neutral - from the nearest two phase legs to the center tap you get a half voltage which can be used for lighting. (typical arrangements are phase-to-phase = 240 volt, phase to neutral = 120 volts) From the third, furthest phase leg you get the unusable high leg. (208V)