Why CT is connected in series?
CT also need to be connected in series because than only current in the secondary winding will N times the current in primary. CT is to measure the current ( like an ammeter) so it is connected in series with the conductor carrying that current.
What happens if CT polarity is reversed?
If polarity is correct, the momentary contact causes a small deflection in the analog meter in the positive direction. If the deflection is negative the polarity of the current transformer is reversed. The terminals X1 and X2 need to be switched and the test can be carried out.
Why CT secondary is star connected?
In potential transformer the primary and secondary windings are star connected, because in star configuration, the line voltage is root 3 times of phase voltage, hence the voltage distribution to each winding is reduced or divided by 1.732 times. Due to that the insulation cost on the primary winding comes lesser.
Why CT star point is earthed?
why Current transformer Star point is grounded 2. It is provided to flow the earth fault current. If CT secondary is not earthed, the primary voltage may induce high potential in secondary winding. To keep the secondary voltage at designed rating (say 110 v) against the earth, secondary must be earthed.
Why is PT primary grounded?
The line is not short circuited in the ground through the potential transformer, though one primary terminal is grounded. The PT is, like all transformers, a wound device. The primary will have a high value of inductance, limiting the current flow to a few mA, and thus does not appear like a short circuit.
Why fuse is used in PT and not CT?
PT is connected in parallel do obviously require short circuit protection by fuse. For CT primary is just a current carrying straight conductor passed through coil which is secondary. Secondary generates feeble voltage so don’t require fuse protection.
Can neutral and ground be tied together?
Whenever you have an auxiliary panel the neutral and ground should not be tied together because the ground wire becomes a parallel path for current with the neutral wire (any current going through the neutral wire will be shared with the ground wire because they have the same connections at both ends).