fan control

[davelerave]

i have to wire a couple of axial fans using electronic voltage controllers

http://www.hydor.co.uk/ebrochures/axial_flow_fans.pdf

page 10 and 15

customer has asked for controllers to be fitted approx 8-10mtrs from fans


i was thinking wire into spur+rotary isolator under fan

from here to starter + speed controller

and then 5-core direct to fan

do i have it right? or is there a better way

thanks

 

[bugsy]

Supply-----Isolator/fcu-------controller-----fan I can;t imagine any other way

 

[davelerave]

needs a starter for 2-wire 'thermal cut-out'


it shows cut-out connected to electronic controller but this is not the case-it needs a starter control circuit


quite a lot for a small fan i reckon

 

[Marvo]

Can you give the exact model number of the fans and speed controller?

If you're using a transformer type speed controller you'll need a DOL stsrter to incorperate the thermal contacts (shown as TK + TK) in the circuit drawings. If you're using the electronic PWM controller then a separate DOL starter doesn't appear to be necessary as there are terminals in this controller for the TK wiring and there's on/off control on the controller as well.

 

[davelerave]

Can you give the exact model number of the fans and speed controller?

If you're using a transformer type speed controller you'll need a DOL stsrter to incorperate the thermal contacts (shown as TK + TK) in the circuit drawings. If you're using the electronic PWM controller then a separate DOL starter doesn't appear to be necessary as there are terminals in this controller for the TK wiring and there's on/off control on the controller as well.

yes electronic -hfc 1.7a but there are no TK terminals in it ??
(i see it shown connected on page 10 alright)

don't have fan model atm


i'll check the fans tomorrow and make sure they have 2-wire thermal cutout

 

[Marvo]

The two wire thermal cutouts usually aren't rated to take the run current of the fan so they need to be wired as a signal, not an inline cut-out in series with the windings. This might alter your cabling plan as you'll need to wire them back to the controller or DOL starter. If you don't see TK terminals in the controller then I would go back to the supplier to clarify.

If the fan doesn't have thermal protection then it will almost certainly have a minimum rotation speed specified somewhere. The controller minimum setting should correspond to this minimum speed if it's correctly specified.

Speed controlling a fan without incorporating the thermal protection is dangerous. Fans are very prone to overheating with prolonged running at low speeds. Lower airflow over the motor and often lower motor efficiencies result in thermal runaway of the stator windings. If the overheating is marginal then premature bearing failure in a few weeks, if it's major then insulation breakdown of the windings much sooner.

 

[bugsy]

Im obviuosley missing somthing here , the TOC will be interal to the coil, and why the DOL starter
Schematic looks quite straight forward to me

 

[Marvo]

The bi-metalic thermal (or thermistor) is strapped to the windings but it's shown as a control device not a load current isolating device. If there's no TK terminals in the speed controller then it would require a DOL starter or at least an extra contactor to facilitate control of the fan.

​

 

[bugsy]

He directed us to a single phase fan and your looking a three phase fan .

 

[Marvo]

Oops, sorry wrong image, thanks for pointing that out, I've put in the right one now. The TOC TK wiring is the same though for single and three phase fans. It states on both circuit diagrams 'Thermal cut out connect into starter control circuit'.

 

[bugsy]

But he is using the speed controller, wheres the TOC

 

[Marvo]

I don't think I understand the question.

 

[davelerave]

The bi-metalic thermal (or thermistor) is strapped to the windings but it's shown as a control device not a load current isolating device. If there's no TK terminals in the speed controller then it would require a DOL starter or at least an extra contactor to facilitate control of the fan.

View attachment 2745


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that's my thinking

 

[davelerave]

ok got this sorted

some of the schematics seem to be inaccurate

>supply to fan from electronic controller
> cutout is 'pre-wired' in fan unit in series with winding
>if cutout breaks/makes- fan won't restart until controller is switched off/back on again


may still have to fit a starter as they have key-stops(no start buttons) and contactors on sockets i am spurring off- so fan would re-activate via key-stops

switched fcu---starter---and speed controller will do then-pretty safe isolation when switched spur is turned off

thanks

 

[bugsy]

Got there in the end!

 

[davelerave]

i assume they changed to internally wired 'cut-out'

to ensure overload protection is present when wired direct- although fan may restart

 

[Marvo]

i assume they changed to internally wired 'cut-out'....

I hope so. Time will tell but if the suppliers are happy with the load current through the thermal they should cover the warranty if it burns out.

 

[davelerave]

i rang them -they told me


you could certainly imagine a lot of these cut-outs being ignored(edit)-if they require starter control circuit

it has to be warranteed! as fan comes pre-wired this way

 

[Marvo]

Yep, they often get bypassed or just plain ignored. You usually only find out when it's too late.

If it's pre-wired then you're definitely covered and I would have more faith with it pre-wired than just the salesman say so.

 

[davelerave]

ya -i meant to say ignored

not really bypassed if they don't touch it