A. Open
B. Closed
C. Closed or Open
D. None Of above
Ans: B. Closed
Explanation : If keep open Secondary winding of current Transformer Heavy voltages Generated In secondary winding and insulation of secondary winding may damage.
66Kv or 11Kv or other voltage classes having very higher voltages and and very higher currents which can not be directly measured.
For measurement of this higher current , Current Transformer is required which step down this higher current to measurable limit.
Current transformer is step down transformer which is step down the current from higher level to lower level.
Current transformer having Primary Winding and Secondary winding.
In current transformer primary Winding having only one number of turns and secondary winding having large number of turns.
Primary winding of current transformer having very large cross section area secondary of current transformer having very small cross section area.
Current transformer used for measurement of current , protection of Transformer and lines etc.
Current transformer secondary side current are o.1 A , 1A or 5A which is very lower current and which can easily measured by measuring instruments.
Current transformer primary side having very higher current 10A to 3000A or more.
Good To know :
A 300 : 10 , current Transformer is used along with an ammeter . if ammeter reading is 3 A, estimate line current or primary current
Here Current transformer ratio = 300 / 10
where formula for CT ratio = I1 / I2
here ratio = 300 / 10 given and also ammeter current I2= 3 A which is CT secondary given
I1 / I2 = 300 / 1o
I1 / 2.7 = 300 / 10
I1 /3 =30
I1 = 30 * 3
I1 = 90 A
so here line current or CT primary current is 90 A