Electrical Engineering

For open circuit test of transformer, the secondary is open circuit and the circuit impedance is largely inductive due to the core impedance having high L as compared to R. hence the power factor is reduced, thus , we use low power factor wattmeters.

It checks for the sum of phase currents which is meant to be zero in case of Star point Grounded transformer. In case of any discrepancy i.e star point shifting with respect to one of the phases the sum of currents stands no longer null. This is when our NDR comes into play as it will avoid whole feeder tripping in case of 2nd fault occurring on the same transformer.

An aM fuse is usually an industrial fuse with an operating characteristic designed to protect inductive loads e.g. motors. Using a general purpose 'gG' fuse in such an application could lead to nuisance operation because the fuse cannot withstand the initial start-up surge.

It refers to the number of cycles (frequency) of the a/c source per second; 1Hz=1 complete cycle per second.

Ohm's Law

Volts = Current x Resistance

Amps = V / R

110 / 20 = 5.5 Amps

A CVT (Constant Voltage Transformer) is always better than a Servo Stabilizer. But a CVT is costlier than a Servo Stabilizer of same rating.

phlebotomy

In short circuit test very low voltage at primary approx 5 % of the rated voltage is given and secondary is short circuited by an ammeter. Due to low voltage very low flux is developed in core of the transformer and due to that iron losses are very low which can be neglected.

By Rizwan:

actually it is operated at (10-15)% of the rated voltage and as you know n case of low voltage low magnetic flux is produced and then there will be low magnetic field density(B). and we know hysteresis and eddy current losses depend on (B).as in case of :

hysteresis depends on B^1.2 and

eddy current depends on B^2

So if B is low then both losses(collectively called constant losses) will be very very low.

We can convert a 3 phase ac motor into generator by changing phase sequence of the ac input cable of that motor

0.7 V

It's not - I have seen 50kVA, 100kVA,...15000kVA, 36000kV, 180000kVA to name a few examples. Near where I live, I don't believe there are more than a few transformers rated in multiples of 11 as you state.

transformer action doesn't depend on power factor that is why we indicate its rating in KVA

when source resistance and load resistance are equal maximum power is transfered

A: The main advantage for a current source transmission is low source impedance. extraneous voltage influence is reduced by that characteristic.

80

g55

Balanced load means no unbalanced currents, so the neutral current should be near zero.

there will be no neutral point in the circuit and high voltage will be across the transformer coils

If fluid is lost due to component failure, you will get total brake failure (loss of all braking except parking/emergency brake) on a single circuit system. A dual circuit system will only fail in one circuit, leaving the remaining circuit working. It is therefore safer.

Parallel connections will draw more current than equivalent lights connected in series, so the parallel configuration will be brighter.

Phase barriers enhances the distance between two phases thus making the medium between two phases less vulnerable for breakdown.

If they are grounded they get an electric shock or electrocuted. If they are not grounded or in simultaneous contact with the neutral wire, nothing. That's why birds can sit on a high voltage wire and survive; they are not grounded.