Wiring a motor

[Scrappy11]

Hi all, newbie here with an opening post/problem

I've just acquired a metal lathe, and to cut a long story sideways I've been having problems wiring the motor to a switch box. The FLA reading on the motor says 3.75, so I bought a switch box with an overload amp rating of 2.5-4 amps (assuming that would be good for the motor). When I plug the motor directly into the socket, there's no problem with the fusebox in the garage (where it's set up), however when I wired it up to a switch box, it's constantly tripping the RCD.

So basically my question really is - where the hell am I going wrong?

ANY advice/ideas/insight on the matter would be massively appreciated, any details just ask.

Ta
Dom

 

[Knobhead]

You need to give more details. Voltage, single phase or three phase? Connections etc.
What is the supply voltage? Some photographs would help.

 

[Scrappy11]

ok, this should be everything:

supply voltage is a normal 240v socket

(on the motor)
220-240 volts
single phase
3.54 (sorry not 3.75) F.L. Amps
0.5 HP
Class E (I don't know if this is relevant)

(switch/starter)
DOL Single Phase Motor Starter c/w Overload of Choice

2.5-4 Amp overload
240 V contractor coil

here are some pics of the motor, inside the starter and inside the starter housing.

 

[infinity]

Cant really make out how you have wired that? There is a red in L1 and brown in L2?

 

[Knobhead]

Hope you can follow this.
View attachment 12233

 

[Scrappy11]

Cant really make out how you have wired that? There is a red in L1 and brown in L2?

That's how it came when i bought it from this fella off ebay

 

[Scrappy11]

thanks a million Tony, I'll give it a whirl and report back tomorrow if there are any problems

 

[Guitarist]

You need current flowing through all 3 contacts as per Tony's diagram, otherwise the O/L will see an imbalance and trip.

However, you say that it is tripping an RCD in a switch box? but not on the garage fuseboard. Please explain in more detail how your supply is set up.

 

[Scrappy11]

You need current flowing through all 3 contacts as per Tony's diagram, otherwise the O/L will see an imbalance and trip.

However, you say that it is tripping an RCD in a switch box? but not on the garage fuseboard. Please explain in more detail how your supply is set up.

I have a separate fusebox for the garage. Basically the house has a main fusebox (standard), but a separate wire runs out of the fusebox into a secondary fusebox for the garage since it's detached from the house. I think (I'm not pro, I've just worked this out for myself) that maybe it's drawing too much power? The motor is fine when plugged into a normal socket, it's just when I wire it to the switch/starter that it trips the RCD in the garage and thus the main switch in the house.

 

[Marvo]

If the motor runs fine when plugged in to a socket then there's a good chance it's you wiring of the DOL starter.

It might be worth a quick IR test of the windings, if they're okay (>2Mohms) then wire up as per Tony's diagram.