The circuit which carries the electric signals directing the performance of a controller, but not carrying the main circuit power.

a feedback circuit that subtracts from the input

a circuit in a piece of equipment or an electrical circuit that carries the signal determining the control action, as distinct from the power used to energize the various components.

The circuit that controls a relay or contactor.

The circuit that carries the electrical signals which direct the performance of the components that control the power circuit.

A circuit in a closed-loop system, typically containing an error amplifier, which controls the operation of the system to achieve regulation.