# How would you design an electromagnet for maximum force when you have a fixed power available?

There are number of variables like current, wire dia, number of turns, dia and length of electromagnet. The distance at which force is applied is constant

The distance is nearly 12 inches. Power is nearly 88.4 KW. The electromagnet should be not more than a few meters at max. Weight is not much of an issue. Calculation is not needed just need an idea on how to select the optimum values of variables. The formula I am using is F=(mu)(n*I)^2/2g^2 mu= permeability

The project is about use of regenerative braking to charge electomagnets to attract the rails. This force is being utilised to avoid derailment during train emergency braking. Just a college project in analysis not any research.

• So, have you googled the formula for a force from an electromagnet yet? Commented Nov 3, 2017 at 17:52
• I know the formula. The problem is the selection of the values of the parameters for producing maximum force. The thing is that if the wire with less dia is chosen than the no of turns increases but the maximum current it can handle decreases and if the wire with larger diameter is chosen than the no of turns decreases. And the area of electromagnet is also a variable as the amount of turns also depends on that Commented Nov 3, 2017 at 17:57
• "KW" is kelvin-watt. You mean "kW" for kilowatt. Commented Nov 3, 2017 at 18:09
• Multiple posts of the same question : engineering.stackexchange.com/q/17894/10902 Commented Nov 3, 2017 at 18:48