SSR
Beside the motor controller is a solid state relay, or SSR, which helps make your EA system more reliable and efficient.
To switch on and off the power supply for a powerful electric motor, it is not practical to run a large cable to a huge switch. To solve the problem, a relay (also called a solenoid or contactor) is used as a remote operated power switch that allows a very small electric signal (i.e. a small switch and small wire) to remotely switch the power to the motor. Traditionally, electric boats and other electric vehicles have used a contactor, a large mechanical device much like the solenoid that allows you to start your car with your key. It makes a click when you turn it on and it must remain powered to stay on. These contactors typically use a significant amount of energy, and left on for long periods they will drain your battery.
SSR’s have no moving parts and use very little energy, Ours is made by Crydom, their model HDC100D120H. It uses just .01 watt to stay on and is powered from the electronics in your motor controller, a safety feature that is not possible with a mechanical contactor. You can check out the Crydom at
http://www.crydom.com/en/products/catalog/hdc-series-dc-panel-mount.pdf
hdc