Models such as five p10, what is the meaning of the 5 p20? How to choose?

 ac motor Lamination 220v class B/F 
Specifications
1. Lamination of electric motor 
2. IP54 class F 
3. 100% copper 
4. silicon steel stamping 
5. stunning performance 
5 p10, 10 is behind the accuracy limit factor. 5 p10 said when a current is 10 times of the rated primary current, the winding composite error of plus or minus 5% or less. The significance of accurate electricalmotor1.blogspot.com limit coefficient is within the scope of guarantee error in the plus or minus 5%, multiples of a current must not exceed the rated current, if the primary current is bigger, be about to choose 5 p20, might even choose 5 p30. By the calculation, for example, you need to have protection, short circuit current under the largest operation mode is 4 KA, you choose the current transformer is 150/5, 5 P10, ANP gost motor this means the current transformer in 10 times a * 150 = 150 a = 1.5 KA, can guarantee the winding composite error of plus or minus 5% or less; 

115/120 V AC Voltage and Three-phase Phase small 240v electric motor
Specifications
1.Specifications1.3-phase asynchronous motors 
2.IEC standard 
3.OEM 
4.Voltage:50HZ &60HZ;380V&415V 

5.Protection class: IP54 
And probably after short circuit, current exceeds 1.5 KA, even achieve 4 KA, then carlt composite error of plus or minus 5% or less, if choose 150/5, 5 P30 current transformer, current transformer in 150 a * 30 times = 4500 a = 4.5 KA, can guarantee winding composite error of plus or minus 5% or less, but only 4 KA maximum short- circuit current, in the full range, can ensure the accuracy of protective current transformer. But in practical application, in order to reduce costs, protect the electric generator does not need too high accuracy, 10 p have been able to meet this need, and when choosing current transformer, also it is not necessary to ensure the maximum short-circuit current, also guarantee the accuracy, generally near the protection setting value can guarantee accuracy.