Home > Product Groups > Power Control (Thyristors) > Thyristor Power Controllers > Three Phase (3PH), 3-leg > How to size a 3PH thyristor? > 

 

How to size a Three Phase Thyristor

 

The formula below provides a simple method to calculate the thyristor current for typical resistive loads. The calculated value of I should then be multiplied by 1.2 (safety margin) to allow for variations in supply voltage and other tolerances of the load. 

 

Three Phase (3 or 4 wire load, 2PH or 3PH)


Thyristor current (I) = Power (WATTS)

                                    1.73 x V

Example: A 53kW load across 415V AC, 3PH supply

              I =      53000     = 73.8A

                    1.73 x 415

 

If we apply the safety margin of 20%, the thyristor current equals:

73.8 x 1.2 = 88.6A

 

We can therefore use a 90A, 415V AC 3PH thyristor unit

 


 

 

See Also: Three Phase Selection Guide