i want to calculate the Current limiting resistor value and wattage for Power transformer

Thread Starter

Muhammad Irfan 6

Joined Dec 5, 2017
Hey Guys .
Recently im working on a power transformer the specification of that transformer is
220Vac input and 100VAc output 50A .
Of course in startup it take a high inrush current and that time my circuit breaker trips .
I make a soft starter circuit for it to resolve this problem. i used a 100A relay it will turn on after 2 second of delay.
now i want to calculate the current limiting resistor which connected parallel with the relay contacts .


Joined Mar 14, 2008
What is the load?
The resistance would be 100 divided by the maximum current you want.
The wattage can be low since the power only occurs for 2 seconds.
Likely a 1W resistor would be sufficient.


Joined Jul 18, 2013
Is this due to a high load and/or capacitor bank being connected? If so you could disconnect this until the initial primary inrush was over.