What is P1 and P2 in current transformer?
What is P1 and P2 in current transformer?
P1 indicates the side on which the current source is located, whilst P2 indicates the load side.
What is the function of CT coil?
A Current Transformer (CT) is used to measure the current of another circuit. CTs are used worldwide to monitor high-voltage lines across national power grids. A CT is designed to produce an alternating current in its secondary winding that is proportional to the current that it is measuring in its primary.
Why CT S2 is earthed?
To prevent the secondary circuits from attaining dangerously high potential to ground, these circuits have to be grounded. Connect either the S1 terminal or the S2 terminal to ground.
What is burden of CT and PT?
The burden of CT is the maximum load (in VA) that can be applied to the CT secondary. The burden can be expressed in two ways. The burden can be expressed as the total impedance in ohms of the circuit or the total volt-amperes (VA) and power factor at a specified value of current or voltage and frequency.
What happens if CT secondary is open?
The secondary side of a current transformer should never be kept in open condition because, when kept open, there is a very high voltage found across the secondary side. This high voltage causes a high magnetizing current to build up on the secondary side which in turn causes high flux and makes the core to saturate.
Why CT is grounded?
The grounding of current transformers is important to both safety and the proper operation of the protective relays. To assure the safe and reliable operation, the neutral of the current transformer secondary should have a single ground location for each circuit.
Why CT secondary is 1A or 5A?
The standard CT secondary current ratings are 1A & 5A,The selection is based on the lead burden used for connecting the CT to meters/Relays. 5A CT can be used where Current Transformer & protectives device are located within same Switchgear Panel. 1A CT is preferred if CT leads goes out of the Switchgear.
How do you size a CT?
For best accuracy, the diameter of the conductor being monitored should be more than half the opening size of the CT. For example, a 4/0 AWG conductor is typically 0.64 inches in diameter and commonly carries 200 to 250 amps. This will fit in a 0.75 inch CT and largely fill the opening (best case for accuracy).