Tricky but Easy Electrical Engineering!
Moving Iron Instruments are the most common type of ammeter and voltmeter used at power frequencies in laboratories. These instruments are very accurate, cheap and rugged as compared to other AC instruments. Working Principle of Moving Iron Instruments: In Moving Iron Instruments, a plate or van of soft iron or of high permeability steel forms … Read more
The deflection of needle of moving iron instrument is given in terms of rms value of voltage or current. As the angular deflection of Moving Iron Instrument is proportional to square of operating current, therefore the instrument has basically square law response. Due to this square law response, the Moving Iron Instrument Scale is non-uniform. … Read more
It is a well known fact that Ammeter is always connected in series with the element through which current is to be measured. Figure below shows two cases, in one case ammeter connected in series while in other case, ammeter is connected in parallel. As an Ammeter has very low internal resistance therefore ammeter connected … Read more
A Residual Voltage Transformer is used to measure the residual voltage of three phase system during single phase fault. During normal operating condition, the summation of three phase voltage is zero but in case of single phase fault, the scenario changes and there exists a residual voltage. Let us first discuss residual voltage in case … Read more
Vacuum Circuit Breaker Vacuum Circuit Breaker (VCB) is one where vacuum of the order of 10-6 to 10-10 torr is used as an arc quenching medium. 1 torr is equivalent to a pressure represented by a barometric head of 1 mm mercury. Vacuum Circuit Breaker is used for low and medium voltage applications. Construction of … Read more
“The Transient Recovery Voltage refers to the voltage across the pole immediately after arc extinction. Such voltage has a power-frequency component plus an oscillatory transient component.” In alternating current circuit breakers, the current interruption takes place invariably at the natural zero of the current wave. After a current zero, the arc gets extinguished if the … Read more
Heat is the prime cause which leads to electrical insulation deterioration. Some possible causes of heat generation in the electrical insulation are as follows: Heat is generated in the electrically stressed insulation, due to dielectric loss and conduction currents. Heat is imparted to insulation by the neighboring current carrying parts. Now if we look at … Read more
Torque Slip Characteristics is the graphical relationship between the torque and slip of an Induction Machine. This characteristic is very useful for the stability analysis of the machine. Electromagnetic torque in an Induction Machine is given as Te = [Kx(r2/s)] / [(Re + r2/s)2 + X2] …………………(1) Where K = Constant From the above equation, … Read more
Transient Recovery Voltage (TRV) is the voltage appearing across the contacts of circuit breaker after a switching action. Typically, every transient TRV has high amplitude and high frequency. In this post we will be disusing the Effects of Transient Recovery Voltage . For detail on Transient Recovery voltage, read Transient Recovery Voltage (TRV) Transient Recovery Voltage … Read more
Definition: A point charge at rest creates a force field in its surrounding. This force filed is known as Electric Field. You can understand force field like a field created by a magnet in its surrounding due to which iron piece get attracted toward the magnet. Another example of force field is gravitational field. Thus, … Read more