Oh yes it is! Except for when you are pressing the stop button, the motor and relay coil are in parallel; you can't energise one without the other. The start and stop buttons will carry the motor current until the relay operates. Unless you have special electricity that knows only to flow from left to right!
My point about the pressure switch was this: Any decent manual switch will start a 1/4hp motor, it doesn't specifically need a relay/contactor/starter. The advantage the relay provides is no-volt release, i.e. freedom from unexpected starts. But a compressor motor controlled by a pressure switch starts without warning anyway, largely negating the advantage of the NVR. Therefore, unless the relay is used to relieve the motor load from the pressure switch, there's little point in using one, an ordinary switch will suffice.
And yes, I do realise that one relay can't both latch the buttons and relieve the pressure switch!
Last edited:
