Power Switch Question

Depends on whether you're talking AC or DC, the voltages involved, and the amount of current you want to switch. But MOSFETs are good up to about 200V DC and 100A (not necessarily at the same time). International Rectifier (irf.com) has lots of good information. Remember to put a snubber across the load to kill those inductive kick back voltages.

I would use a FET too with diode across your inductive load pointing the opposite direction of current flowing through the inductor.

I suppose you use DC.

When the switch is closed, the current starts from zero and increases linearly with time: I(A) = V(Volt)/L(H) x t(sec). From your data (t=17 msec, L= ?, V= ?) you can calculate the final current.

Generally, with inductive loads, there are no problems at start. At stop, a simple diode accross the inductor destroys the stored magnetic energy = 1/2 x L x Ifin^2.

The mean power dissipated in the diode is: 1/2 x V^2/L x Ton^2/(Ton+Toff).

P.S.: question to CR4: when the editor will enable an easier writing of equations ?

Use zero-crossing detector for 60 Hz AC (time of cycle is 16.6667 mS); count to 3; turn on for 1 out of 3 cycles.