How to wire a modern contactor to a Mk1 Bantam

[wilson logan 1Participant @wilsonlogan1]

Hi All,

I want to change the old contactor on my Bantam to something more modern (Siemens 3RT2015-1AF02).

I’m reasonably happy with the connections to be made other than the black wire (top right).

I believe this is the e-stop connection for the foot brake switch (and possibly the chuck guard & end stop).

Normally e-stops are wired across the NC positions of the contactor (21NC & 22NC) but I have only one wire.

What should I wire the other side of the NC contact to? Earth?

Cheers,

Wilson Logan.

[noel shelleyParticipant @noelshelley55608]

Assuming that the coil circuit is on the live side then what coil voltage 240v or 415v ? If 240 then wire Phase to neutral, if 415v Then wire across 2 phases. Taking it to earth sounds very wrong and likely to cause alsorts of trouble. The various stop switches will all be parallel across this circuit, breaking the circuit will drop the coil. UNLESS you have a low voltage control system with a 24v coil, that’s another ball game ! Noel

[Robert Atkinson 2Participant @robertatkinson2]

An E-Stop should not be wired in parallel (across) a normally closed contact on the contactor they control. If you do the contactor will effectively return the E-Stop to the released state when the contactor is de-energised.
Normally an E-Stop would be wired in SERIES with a Normally Open contact. This circuit latches the contractor on when the start button is pushed.

Robert.

[noel shelleyParticipant @noelshelley55608]

Not thinking properly ! Robert is right, series in a NO circuit. Sorry Noel.

[wilson logan 1Participant @wilsonlogan1]

Thanks chaps!

[EmgeeParticipant @emgee]

Looks like you are short of a pair of NO contacts to maintain the coil connection when energised,

21-22 are labelled NC so can’t be used to maintain the cct.

 

Emgee

[Robert Atkinson 2Participant @robertatkinson2]

As Emgee says that contactor does not look suitable.  Also it has a 110V coil which would be unusual for a small lathe. The Bantam diagrams I can find do not have a control transformer.
Did you select that contactor or was it just “available”?

Do you have a wiring diagram for your lathe?

Any pictures of the old contactor? Ideally installed and one of the part number / rating plate.

Robert.

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