What are pilot or slave relays?

Pilot or Slave relays

Many of the valves and solenoids the speed switch

operates have high currents and it may become

necessary to “buffer” the control against harmful currents.

The Pilot or Slave relay simply “relays” the signal to

the high current load. The input to the Slave relay can

be small but it can control currents up to 100’s of amps.

A diode is shown in the above illustration. This is a

low cost preventative that adds years of useful life.

The diode channels the surges of the slave relay into

a harmless dissipation as opposed to causing arcing

in the control contacts of the engine control.

By placing the pilot relays close to the loads other

electrical benefits occur when the system is in an

environment where electrical interference should be

minimized.

Battery

Speed

Switch

Pilot or Slave relay

High

Current

Load