Many single-phase motors used with refrigeration-duty, semi-hermetic and hermetic compressors require an external relay to assist in starting. How much do you know about these necessary products? An ...

As you can see in the schematic the 12V battery (or use other voltages) is connected with the plus at terminal T1 and minus at terminal T2. The contact 1 and 4 are connected together as 2 and 3 are ...