AC motor soft starter for free DIY

The liquid saltwater rheostat is a simplest way to start an electric motor without blowing out the fuses. The use of AC current is much more on starting when the rotor stays idle. In fact, we should only make a soft ON-switch. Of course, the proper way would be buying:

• an electronic circuit based motor starter block that makes motor starting smooth. 

But, there are other solutions too:

• star-triangle switching (be careful on motor allowed voltage - read signs);
• a capacitor that gives an impulse;
• cascaded (or single) resistors and switches;
• a liquid rheostat (saltwater or drinking soda).

And here is a simple proven solution that may work well without it all - a plastic bottle that avoids immediate bumpy contact that shocks AC line and electric fuses:

For one 220V or all three-phases 380V - the same. Wire goes to the motor as one phase, do not put it in a AC socket. Just make it little adjustable in height. The salt (some big spoons, don't be afraid) will provide smooth resistance needed while the motor starts spinning. The distance between contacts should be about 1 cm. The motor will consume much less when started completely, so we can make an additional switch that connects these wires - additionally to the bottle that heats saltwater. Or connect them inside the bottle.

[ плавный пуск электромотора своими руками бесплатно ]

Disclaimer: do it on your own risk, use dry gummy rubber gloves, boots. AC strike may cause death.