Motor protection

[polo1]

Peeps,
I have been asked to run a supply for a single phase, 3.2a extract fan (systemair AW500E4).
Is it a requirement, recommended or just good practice to include thermal overload protection in such a situation?
Thanks.

 

[clematis432]

Possible fan might have built in thermal protection, but external protection not required

 

[Charlie_]

Does the spec show 3.2 amp at 230v or 240v

 

[Strima]

What does the manufacturer say?

 

[Marvo]

I don't see your particular model in my catalogue so I can't give specific advice.

If the fan has a built in temperature protector, which from memory is usually denoted as S1 and S2 on smaller Systemair fans, it should be cabled back to the DOL starter and used as a trip.

If the fan is single phase and one of those that's hermetic where the bearings can't be replaced and/or it has non overloading blade characteristics ie backward curved centrif for example then I usually wouldn't include a thermal overload because by the time it trips the fan will already be scrap so it's moot.

If it was 3-phase I'd fit a thermal overload to cover against phase fail and voltage imbalance conditions.

 

[netblindpaul]

This fan is likely to be under a DoI rather than a DoC therefore it will require integrating into a complete system, in accordance with the manufacturers instructions, if that requires overload protection then it will need that.
If it is being built into machinery then the requirements of the machinery regulations will apply.
If you are providing the supply, then surely you are terminating at an isolator and the fan controls are by others?
If not then you will need to build the controls in accordance with the relevant UK/EU legislation and likely the relevant standards such as EN 60204-1 for the controls, ISO 13849 if any functional safety is required, ISO 13850 if there are emergency stopping systems involved.

 

[polo1]

Does the spec show 3.2 amp at 230v or 240v

230v

 

[Bobster]

It's roughly 0.7kW (done off the top of my head). So above the 0.37kW threshold that BS7671 states a motor doesn't need OL protection.

It will need OL protection, if not already built into the unit.

 

[clematis432]

Apologies, thought current was .32A ! But even at 3.2A would OL protection be necessary if appropriately protected with conventional fuse/circuit breaker ? Would most sparks think of including OL protection ? Rightly or wrongly (appreciate Rob,s post though) I,m afraid I wouldn,t.

 

[Charlie_]

I replaced an overload this afternoon which was rated from 2.4 to 4 amps

 

[clematis432]

what was wrong with it ?

 

[Charlie_]

Nothing, somebody replaced the existing pump with one rated at 8.6 amps...