cables getting hot on half load

[hollywoodsparky]

I have a machine fed with singles in trunking, 3 phase, all test out ok, short run but cables are getting very warm, unit has a motor which also tests ok .
Any ideas????

 

[Sintra]

Undersized cables possibly.

PS cable operating temperature can be upto 90 degrees depending on type.

 

[hollywoodsparky]

2.5mm
6491x
running at 70 deg
15m long
load 12 amps

 

[Johno]

Factors?

Would it be a pain to stick 4mm2 in, if not I would just do it.

 

[KINKY]

Is it DOL, soft start?

What are the FLC & SC?

 

[hollywoodsparky]

flc 12.5A
sc 30A
DOL with 14-21 o/l
Sorry Johno missed your post.Installation is about 8y old with no probs.
There is an identical motor 3m shorter that is no probs.
Done all the normal stuff just looking for one of those daft faults you sometimes come across.
The heat of the cable is causing the o/l to trip!!!

 

[SirKit Breaker]

Are all the connections tight and clean, is the gearbox or whatever it is driving in good nick, not binding or anything? Simple stuff I know and i dont wish to insult your intelligence but sometimes we look too deep.

Cheers........Howard

 

[jpmiff]

Hi,

Could the motor be wired incorrectly, if it was wired in delta and should be in star this would cause twice the current to flow

just a thought

 

[davelerave]

clamp the cables if you haven't already

 

[Guest123]

Do all cables run together in the same trunking & conduit throughout???

 

[xraytek]

What do you mean by 'half load'?

The thread is going along the lines of just having a motor on a 3 phase supply, but obviously that is not the case.

What is the machine you are referring to?

 

[davelerave]

i assume he means half-capacity( 12amp on 2.5 )

cables hot,overload is tripping -they're drawing a lot more than that

mechanical issue
check wiring

 

[hollywoodsparky]

Thanks guys been on hol ,
In no particular order,
problem is with 1 dol motor on a large (ish)paint plant unit.
singles in trunking then kopex
cables clamped at o/l giving 12.5 11.9 12.3 A
fitter has removed motor and checked says ok
unit has been installed for 8 years no props
re checked terms etc all ok windings all ok
half load being i dont expect 2.5 to get hot (60deg) at 12.5 A