Transformer Outgoing Cable Getting Heated Up

The source of heating could be:- the cable lug-the contact with the breaker terminal or the contact between conductor and the lug [not well crimped or short or else],

-the metallic gland is not split and the magnetic field generated by current will heat the gland,

-the armor is, accidentally, once more grounded not far from the end.

Measure current load on each phase, in-coming & out-going cables. If Amps are balanced, check for corroded/loose/arcing on the joints of offending phase cable.

just to clarify , the heating observed not in the socket terminal connection at breaker.

It is observed at the cable entry gland of the cubicle.

Has the cable entry gland of the cubicle, shorted inadvertently with the cable screen?

yes. cable glanding done as per norms.

What I meant was whether there is a short circuit between cable screen & metallic part of the gland? Is there any current flow between cable gland & cable screen?

definitely cable gland check nut is through the armour only. and i've measured the current flowing in the transformer side armour earthing around 1.5 A.

How much Amps, if any, flowing at the gland nut & armour joint? Some current is flowing there, otherwise it would not get so hot. Will it?

First of all, the LT side of the transformer does it not mean the "low voltage side"?

So why the cable is with screen provided?

Second, if there are 5*1/c 400 sqr.mm cables that means 2 cables per phase. It could be a strong unbalance between currents depending on the laying configuration.

I agree with Joshi: you have to check the current distribution between cables.

If the cable armor is exposed it could touch the metallic gland-if it the gland of the opposite end to transformer end.

"Earth/ground loops".

Make sure each earthed/grounded conductor is only connected to earth/ground at one end.

There may be major possibility of unbalanced current and may reason of poor lugging at breaker end .

I don't discount earth loops, but suggest that since all 14 other cores are consistent the issue is specific to that connection.

You seem to have done checks on all the external connections to eliminate that source, but is it possible that the poor connection/termination is inside the enclosure on that specific connection and heat is being conducted and becoming apparent at the gland.

Gland plate material is it magnetic or non magnetic ?

one more clarification: there is 15 run of 400 sqmm cable from trafo low voltage side to breaker

Thank you. My mistake.

few days back i solved the problem. I want to share with you for ur remarks if any.

i did the following:

a) trefoil arrangement of cables done (earlier it was R phase through one tray, Y-phase and B-phase in similar maner through individual trays. This may result into voltage formation in the armour and result into week gland heating in one cable)

b)LT breaker pane in coming cable glad plate made non magnetic with firm grounding(earlier it was grounded also)

c) grounding pit resistance improve from 5 ohm to 1.1 ohm(combined)

d)chicken mesh provided at the back of the LT cable entry panel in breake cubicle.

on giving 1400 amps load in this bus found the gland temperature was max 43 deg in the same place after 6 hrs of running. till date it is the same.

hope i have taken correct measures.

Congratulations, sostoall, well done.