What is 5P10 class CT?

If you see the specification or name plate of a protection class CT, you will find that it is given like 5P10. This CT can be interpreted as a protection class CT having an accuracy of 5% over a current range of 10 times of normal primary current rating.

What is class1 CT?

CT Class. The standard accuracy classes according IEC are class 0.2, 0.5, 1, 3 and 5. The CT with accuracy class of0.1, 0.2, 0.5, 1.0 accuracy class are used for measurement of electric current. 0.1 and 0.2 accuracy class CT are used in a revenue metering application.

What is difference between 1A and 5A CT?

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.

What is CT rating?

Ratio. The CT ratio is the ratio of primary current input to secondary current output at full load. For example, a CT with a ratio of 300:5 is rated for 300 primary amps at full load and will produce 5 amps of secondary current when 300 amps flow through the primary.

Which is better 5P10 or 5P20?

Its application which differetiate the use of 5P10 and 5P20. If the breaker is used for backup protection say incommer etc you can use 5P20, but if it is say an incommer ACB/ MCCBof PMCC, you should use 5P10 only.

What is class of CT and PT?

The standard accuracy classes of current transformer as per IS-2705 are 0.1, 0.2, 0.5, 1, 3 and 5 for metering CT….Application of CT Core According to Their Class.

Application Accuracy Class
Precession Metering 0.1 or 0.2 BL
Commertial Metering 0.5 or 1.0 AM, BM, CM
Ammeters 1 or 3 CD
Protection Relays 5P10 or 5P20 STU

What are different classes of CT?

Metering CT Accuracy classes are: 0.1, 0.2, 0.5 and 1. In wattmeters, energy meters, and power factor meters, phase shift produces errors. However, the introduction of electronic power and energy meters has allowed current phase error to be calibrated out.

What are the errors in CT?

Errors in Current Transformer :

  • Turn Ratio (n) : For a current transformer, if N 1 and N 2 are the number of turns in the primary and secondary windings.
  • Actual Current Ratio (R) :
  • Nominal Current Ratio (K n) :
  • Ratio Error :
  • Phase Angle Error :

How do I choose a CT ratio?

Correct selection of the primary nominal current is important for the accuracy of measurement. Recommended is a ratio slightly beyond the measured / defined maximum load current (In). Example: In = 1,154 A; selected transformer ratio = 1,250/5.

What does 5p20 5p10 mean?

It means the maximum permissible error will be 5% 20 = Accuracy limit factor indicates that the CT will sense the current with the specified accuracy even with 20 times of its secondary current flows in the secondary.

What is knee point?

The knee point is defined as the voltage at which a 10% increase in applied voltage increases the magnetizing current by 50%. For voltages greater than the knee point, the magnetizing current increases considerably even for small increments in voltage across the secondary terminals.