Axial fan wiring Help

[Matthew Haynes]

Hello,

Wondering if anyone with a bit of electrical know how can help me out on wiring up a fan I got hold of, my plan was to use it to create a DIY dust extractor but I'm struggling with the basics.

It's one of these ...

https://www.conrad-electronic.co.uk/ce/en/product/189390/Ecofit-2RRE45-250X50R-L47-A3-Axial-fan-230-V-AC-1400-mh-x-H-252-mm-x-1035-mm
https://produktinfo.conrad.com/datenblaetter/175000-199999/189390-da-01-en-MOTORLAUFRAD_2RRE45_250X50R_L47_A3_P.pdf

There's four wires coming out, (earth, live neutral and an extra black one) I wired the first three up to a plug and the fan won't start without me turning it by hand, then it increases in speed to the point I'm uncomfortable being around it (sounds like a plane taking off!). It also gets really really hot.

I looked into it a bit more and it seems I should be using a 6uf 400v capacitor to start it, and I guess this is where the fourth black wire comes in? Can anybody advise on how the capacitor should be wired? Will the capacitor help as well with the overheating and seemingly infinite speed, or am I missing another crucial part / have a duff fan?

Many thanks,

Matt

[Adrian Godwin]

See the schematic on the data sheet at https://produktinfo.conrad.com/datenblaetter/175000-199999/189390-da-01-en-MOTORLAUFRAD_2RRE45_250X50R_L47_A3_P.pdf

It requires blue to live, black to neutral, and the starting capacitor between brown and black. So you've connected 230V across the starter winding, which is usually current-limited by the capacitor.

Unsure about the speed, but it probably does explain the overheating.

Probably not damaged if no magic smoke came out.

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[Matthew Haynes]

Thanks Adrian, that helps a lot!

No smoke, just a slight burning smell, hopefully it'll still work - lesson learnt, wiring a fan != wiring a plug :)

I've ordered the capacitor so will see how it goes, should I be worried about safety of stored charges with a capacitor this size (6uf 400v), have seen people suggest soldering a resistor across the terminals to discharge after powering off.

Thanks,

Matt

[Nigel Worsley]

> I've ordered the capacitor so will see how it goes, should I be worried about safety of stored charges with a capacitor this size (6uf 400v), have seen people suggest soldering a resistor across the terminals to discharge after powering off.

There is a discharge path throught the windings, so no problem.

Nigle

[Matthew Haynes]

> There is a discharge path throught the windings, so no problem.

Thanks, is that because this is a run capacitor rather than start capacitor?

[cepm...@yahoo.co.uk]

There are a whole heap of brand new motor capacitors of various values in the electronics laboratory.

Phil

Ioannes 8:32

----- Reply message -----
From: "Matthew Haynes" <monsieu...@gmail.com>
To: "London Hackspace" <london-h...@googlegroups.com>
Subject: [london-hack-space] Axial fan wiring Help
Date: Sun, Oct 21, 2018 19:14

Thanks Adrian, that helps a lot! 

No smoke, just a slight burning smell, hopefully it'll still work - lesson learnt, wiring a fan != wiring a plug :)

I've ordered the capacitor so will see how it goes, should I be worried about safety of stored charges with a capacitor this size (6uf 400v), have seen people suggest soldering a resistor across the terminals to discharge after powering off.

Thanks,

Matt


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[Adrian Godwin]

It's a start/run since it does both. But even if it were a start only and got disconnected by a centrifugal switch when running, it would discharge through the windings when stopped, and be live anyway when running. It's good practice to have a discharge resistor on larger value capacitors at high voltage but I don't think I've generally seen them on motors.

On Sun, Oct 21, 2018 at 8:40 PM Matthew Haynes <monsieu...@gmail.com> wrote:

> There is a discharge path throught the windings, so no problem.

Thanks, is that because this is a run capacitor rather than start capacitor?

[Matthew Haynes]

Thanks for the help, wired up with correct capacitor tonight and the fan starts and runs as expected, no noticeable heat generation either!

Still sounds like a Boeing but am hoping the enclosure I'll build will muffle the sound somewhat. Aiming to make a cheaper more powerful one of these:

http://www.yandles.co.uk/record-power-ac400-two-stage-air-filter-with-remote-3-speeds-and-time-delay/p5004

There's loads of these types of fan on ebay and I paid about the same as a standard desk fan for mine, if it works might be an idea for the dusty workshop once setup (am yet to visit Wembley due to other commitments but hopefully be around as time becomes available).

Matt