Need to diagnose failure in fan motor..need motor datasheet

[treez]

Hello,
We have a Constant temp and humidity oven of part number HZ-2004A
Its Made by Li Xian.
There are three fan motors on top of it.
One has severely overheated and the attached CBB61, 5uF 450VAC capacitor has blown up.
The motor nameplate says:-
Cheeming, 51K90A-CF
90w 220v 50/60hz 5uF 0.58A 1300/1600 r/min

Do you know where we can find the motor datasheet so we can probe its windings to see if they have gone short?

 

[KlausST]

Hi,

"51k90A"
replace the "1" with an "I"
--> "5IK90A" and find it at "oriental motor"

The suffix "CF" seems to be for a special shaft type.
... or it is just the capacitor type.

Klaus

 

[treez]

Thanks,
https://www.oriental-motor.co.uk/Pr..._speed/Induction_motors_world_k_bh/?arid=3464

Yes i think the 5IK90A-CF must be obselete because it doesnt seem to be on their website.

 

[Relayer]

Hello treez,
Has the cap blown up entirely?
If not, does it look like a large electrolytic type or rectangular?
It sounds like a bog standard motor start capacitor.
Please check this link to see if yours looks similar:

Motor Start Caps

You should be able to find a replacement that would suit the dimensions you require.
I've replaced a few of these caps in the past, but on air compressors and a few have
exploded as well with no other problems, so there's a good chance that there's nothing
else wrong. But I have had one where the circuit breaker had exploded as well
I hope the above helps.
Regards,
Relayer

 

[Kajunbee]

Looked around but also had no luck with datasheet. I found a new motor on eBay that seems to match. The model number was 5ik90a-cfmts if you do a eBay search. I don't know how difficult it would be but you may have to probe one of the good motors if you just want a resistance measurement. Hopefully you won't need to remove the motor to do this. I'm guessing the other two motors are identical.

 

[betwixt]

Also note that the capacitor normally has a rated usage time which may be as short as a few thousand hours. Remember that 1,000 hours is only 41 days so a short life may be expected. The longevity is normally marked on the body and as it ages, the value drops. In a water treatment plant near here I have to change them every year or the motors overheat and start blowing 20A fuses. Normal operating current is about 4A.

The motors here seem quite resilient and happy to continue as expected when new caps are fitted. Hopefully yours is OK so check the cap value first and if it is below about 80% of marked value, fit a new one. The purpose of the cap is to provide a phase shift between motor coils in order to 'pull' it in one direction. If the cap drops in value the motor output power drops and its electrical consumption increases.

Brian.

 

[treez]

Thanks, Betwixt i think youve cracked it....yes and i suspect the caps arent in parallel with the motor input...some of the motor power current actually passes through the caps as they are in series with some of the coils?

 

[betwixt]

That is correct, simply connecting AC across the winding would not make the motor turn as all it would try to do is assume one of two positions as the polarity changed. There are actually several windings alternately positioned around the rotor, with all the even numbered ones in parallel and odd numbered ones in parallel (or each in series instead of parallel) . One set is fed directly from the AC, the other through the capacitor. The phase shift provided by the capacitor (if it's the right value!) makes the current peaks in the windings occur at different times so the rotor is pulled from one to the next with the time delay causing rotation.

Obviously if the capacitor value is wrong, the time delay is too long or too short and the pull from one position to the next becomes unbalanced.

Brian.

 

[treez]

Thanks, the capaitor was ...
CBB61 5uf 450v 50/60hz

It blew up.

Again we couldnt find the datasheet for the cap.

- - - Updated - - -

There is detail here
**broken link removed**
..so it looks like we need one with tan delta < 0.002 (50Hz)

 

[betwixt]

RS and Farnell sell them but in a different casing, it's unusual to see them in a block, they are normally in a cylindrical can. Try Farnell order code 1219038 the page shows wired or tag ended types.

Brian.