Electrical Engineering

so that when damping torque=controlling torque,the pointer comes back to the zero position...i.e. the main role of controlling torque is to ensure to bring the pointer to the 0 position when deflecting torque is removed

A motor will turn when only the armature is excited, if there is enough residual magnetism in the field.

Ohm's law: Voltage = Amperes times Resistance. This means that increasing voltage while keeping resistance the same must result in an increase of current.

No. The larger the conductor the lower the resistance and the higher the ampacity.

field strength

The phase angle between voltage and current in a purely resistive circuit is zero. Voltage and current are in phase with each other.

Flux linkages of an inductive circuit can not abruptly change.

Proof:- This can be proved by the logic of contradiction. Let the flux linkages abruptly change. Then by Laws of Electromagnetic induction infinite voltage is to be induced Infinity is conceptual and not practical. Hence the flux linkages cannot abruptly change in any practical sense. Hence the theorem.

Some discussion and limitations of the theorem:- Although Infinity cannot be brought forth into the practical world, it is conceptualized in a limiting process by defining Impulse function. Thus if impulse functions can be considered, the constant flux linkage theorem can be violated.

How to justify the word "Constant"?:- Considering a closed pure inductive circuit carrying a current I, it remains constant for ever, until infinity.

synchronise means parallel operation.

to do so first you must understand the winding level chaos. what is 30 deg and -30 deg. then automatically you can come to a conclusion

3 phase reverse relay can be utilized to control 480V motor 60HZ for controlling their speedspeed.

(coded value - measured value) /coded value x 100

The Synchronous motors will operate at a constant speed from noload to fullload. Even it is classified as an AC motor, we have to fed the motor both AC and DC supplies. That we have to supply DC to the Field (Normally Rotor) and AC to the Armature (Normally Stator).

An open loop transfer function is the transfer function of a system without incorporating the feedback component.

For example, where the closed loop transfer function with unity feedback H(s) = G(s)/(1+G(s)) it can be deduced that the open loop transfer function is Y(s)/U(s) = G(s).

Diode is a non-ohmic conductor since in diodes current-voltage relation ship does't obey Ohm's law....the relationship between current and voltage is nonlinear here,...

Motor runs by the principle of Michael Faraday's Electromagnetic Induction. It is defined as

"when a current-carrying conductor is located in an external magnetic field perpendicular to the conductor, the conductor experiences a force perpendicular to itself and to the external magnetic field".

The direction of rotation is determined by the Right-hand Rule and is "if the right thumb points in the direction of the current in the conductor and the fingers of the right hand point in the direction of the external magnetic field, then the force on the conductor is directed outward from the palm of the right hand".

Wattmeter is an intrument which is used to measure the power consumption of an Electric circuit or an appliance which is connected to the supply in terms of Watts.

You can't. All single phase motors can only rotate in the direction in which they were manufactured. That is either clockwise or counter-clockwise. Only three phase motors can be reversed by changing the connections. Most ceiling fans have two sets of wiring in their motors so that a direction switch determines which way the fan rotates.

meter calibration by potentiometric method

The reduction in the size of the circuit in a microprocessor will (generally) allow the device to be run at higher clock speeds. This will be due to shorter circuit pathways. It will also increase the challenges related to keeping the device cool, and there are some other variables that come into play when we scale something like a micro-p down.

LC means coil capacitance circuit RC means resistance capacitance circuit

The working principle of these instruments is same as that of the d'Arsonval type of galvanometers, the difference being that a direct reading instrument is provided with a pointer and a scale.

The basic principle of this device is the interaction of magnetic field of the compass (a permanent magnet) and the field around the conductor (a simple electromagnet)

Inductive Ammeters do not make physical contact with the circuit, but measure the strength of the magnetic field surrounding the wire carrying the current and measures the strength of the magnetic field that surrounds any conductor carrying a current.

This means that the meter probe surrounds the wire(s) carrying the current and measures the strength of the magnetic field that surrounds any conductor carrying a current.

It is a moving-coil galvanometer with a selectable array of shunts and series (bobbin) resistors. Shunts are also resistors but they go in parallel to the meter to restrict current through the meter itself and allow the meter to measure total current flow. The meter is connected in series in the circuit where you want to measure the current and the resistances are low. Series resistors are large and restrict current through the meter as well but the meter is connected in parallel to measure voltage drop. The maths and principles are very simple if you draw them out even if they don't seem so from a description. Resistance measurements are usually a simple current measurement and the meter is calibrated to follow Ohm's law. In old meters (such as the big black AVO meters from 50 years ago and more), for improved accuracy, a special extra "standard" cell was fitted solely for resistance measurements.

If the circuit is carrying current then that means that the load (resistance) is in the circuit. if an ohm meter is connected in the live circuit then there would be some voltage drop at the ohm meter but as the meter has very less resistance, this would damage the instrument.