I am trying to find out what size capacitor is needed, for a friend. He has a 240v, 25amp, 50hz? motor that he wants to power for 5+ seconds after power is removed. Does anyone know what size capacitor would be needed? I've tried the formulas I found online, but I don't quite understand them, so any help would be appreciated.
Yes, I believe its AC... So the likelihood of removing power and the motor and it continuing for a few seconds is unlikely. I'm guessing the voltage drop would be too quick? What about if it was a DC motor?
Yes, I believe its AC... So the likelihood of removing power and the motor and it continuing for a few seconds is unlikely. I'm guessing the voltage drop would be too quick? What about if it was a DC motor?
Yes, I believe its AC... So the likelihood of removing power and the motor and it continuing for a few seconds is unlikely. I'm guessing the voltage drop would be too quick? What about if it was a DC motor?
You don't need to store AC, just store DC and convert to AC. Now, 25A for 5 seconds is 125 Coulombs. Assume a 60% overall efficiency so "all" you need is 208 Farads at 240 volts. That's a walk in the park. Just call DigiKey. It can help you.
You don't need to store AC, just store DC and convert to AC. Now, 25A for 5 seconds is 125 Coulombs. Assume a 60% overall efficiency so "all" you need is 208 Farads at 240 volts. That's a walk in the park. Just call DigiKey. It can help you.
as was said earlier, an inverter (or UPS) for that load will be very expensive. the OP still hasn't got back to us as to why the strange requirement. from what little he did say, it sounds like a power fail situation, where the motor needs to move something into a convenient position when the power fails.
I agree that its a weird request. My friend 'thinks' he's an inventor. He has given me very little details, only a picture of the motor label and that he wants a cap to power it. Obviously, by the response, he's in daydream land in regards to powering a motor off of a cap. I suggested to him a battery or some sort of backup power source, but he said its no good. I tried to pry more details out of him, but nothing. My 'assumption' (based upon my online searches), I can only assume that he's trying some sort of perpetual energy thing, but I could be wrong. But all of your information has been helpful to get him off my back
You need a timer switch. You can design a 555 timer that is re-triggered for every applied AC peak so it stays on. When the refresh is removed it can be set to time out 5+ seconds later, driving a relay to supply the motor AC power.
You need a timer switch. You can design a 555 timer that is re-triggered for every applied AC peak so it stays on. When the refresh is removed it can be set to time out 5+ seconds later, driving a relay to supply the motor AC power.
A flywheel option would be best, as already suggested.
In the power industry tap changer drives have a heavy flywheel on the motor which is brought up to speed first, then releases the geneva to do the actual tapchange.
This is to avoid getting the contacts stuck between the resistive path in case power is lost during the event.
The actual process takes 5 to 7 seconds.