Contacts A1 maintain power to the relay even though the forward button is released. This will operate as the return path is via the NC contacts of D1. When the forward button is pressed, a positive battery is applied via the NC contacts of B1 to the coil of relay RA/2. ![]() This circuit has a built-in safeguard against that condition.Īssume that the motor is not running and that all relays are unenergized. Putting a motor straight into reverse would be quite dangerous, because when running a motor develops a back emf voltage which would add to current flow in the opposite direction and probably cause arcing of the relay contacts. ![]() The reverse button will cause the motor to run continuously in the opposite direction, or until the stop button is used. The Stop button must be used before pressing the reverse button. When the forward button is pressed and released the motor will run continuously in one direction. ![]() At first glance this may look over-complicated, but this is simply because three non-latching push button switches are used. Relays control forward, stop and reverse action, and the motor cannot be switched from forward to reverse unless the stop switch is pressed first.Įxcept for the back emf diodes across the relay coils this circuit is identical in function to the example shown on the relay contact labeling guide in the practical section. A DC motor reversing circuit using non latching push button switches.
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