Electric generators powered by large diesel engines (the prime movers) generate electricity that move the heavy rig equipment such as the rotary table (or top drive), mud pumps and drawworks. Electric drill rigs are more expensive than mechanical rigs, but offer some nice advantages in return.
[pdf] A soft start kit for home air conditioner units gradually ramps up the voltage, allowing the compressor to start more gently. By reducing the startup amperage, soft starts work to minimize the impact on your home’s electrical system.
[pdf] Most simply, air compressors work by doing exactly what it sounds like they do – they make use of air pressure to get the job done. First, they compress air it into a smaller volume from what it originally was. Onc.
[pdf] 
