How to set up current reversing relays
|A current reversing relay setup is a easy way to operate motors, actuators, and pumps in either direction
with minimal wiring & switches. These relays could be mounted near the device you intend to operate reducing the amount of
heavy gauge wiring you have to run resulting in a neater more efficient install & less overall cost.
What you'll need
*Assorted lengths of wire in several colors to make tracing easier
*Two 5 pole relays
*Crimp On Terminals
For this example i'll use a fairly common & practical use for a current reversing setup. Let's say we have a vehicle that never had power locks but it would sure be nice if it did. What we will have to do is either find a set of factory door actuators or use some of the push/pull aftermarket actuators that are designed for this purpose.
Most of these systems are two wire actuators which require you to apply 12 volts to one wire and ground to the other to make the actuator extend, reverse these wires and the actuator retracts. Now we could run a ton of wires to a switch that would do this somewhere in each door but if we use a couple of inexpensive relays we can put the relays wherever is convient and just hook up the two wires.
How it works:
Each relay is wired to output +12 volts from terminal #30 when they are activated (Terminals #30 & #87 are connected), when the relay is inactive or at rest it outputs a ground through terminal #30 (Terminals #30 & #87a are connected).
Our switch is a common SPDT (single pole double throw) momentary switch, this simply means it has one pole (connected to ground in this case) and two throws, up and down. When you press the switch in the up direction the relay on the right side of the diagram is activated and sends +12 volts down the green wire. Since the relay on the left is still at rest it is sending a ground to the blue wire to our acutator.
This will operate the actuator in one direction (the way you connect the wires to the actuator could vary so if up isn't up simply reverse the actuator wires.) Pressing the switch in the down position will send a ground to the relay on the left side of the diagram activating it. Resulting in the actuator going in the opposite direction.
This can have many uses, such as a motorized amplifier rack, or hatch actuator. As well as door lock actuators or pumps.