Control from two locations

One motor is started and stopped from two places, for example the field and the control room. The stop buttons go in series and the start buttons in parallel.

Stop buttons S01 (field) and S02 (control room) in series. Start buttons S11 and S12 and the holding contact of K1 in parallel.

How it works

1At rest

Both stop buttons are closed, but all the start branches are open.

2Start from the control room

S12 closes and K1 energises. The holding contact in parallel closes.

3Start released

K1 stays on through the holding contact.

4Stop in the field

S01 opens, K1 de-energises and the self-holding is released. The motor stops, even though it was started from the other location.

Control from two locations is a self-holding circuit with two start buttons and two stop buttons. The same principle also works from three or more locations.

The rule

Stop buttons in series. Any one of them breaks the circuit and stops the motor.
Start buttons in parallel. They are wired in parallel with the holding contact, and any one of them energises the contactor.

More control locations

A new control location is added the same way: its stop button in series with the other stop buttons, and its start button in parallel.

Common mistakes

The stop buttons are wired in parallel. Then neither of them stops the motor on its own, because the current flows through the other one.
The start buttons are wired in series. Then the motor starts only when both are pressed at the same time.