Plug-in hybrids, meanwhile, could charge at night, when demand is low, and even pump power back to the grid while parked during the day.

The top plug has a solid body that provides positive indication of contact with the landing collar and bottom plug through an increase in pump pressure.

First close the plug of a vacuum or pressure meter, if so mounted on the pump, connected to the pump before starting the motor and then open it when the motor move in the normal speed;