Olflex Cable Over-heating
Olflex Cable Over-heating
(OP)
Hi,
We are using a 4 * 50mm Olflex cable from a VFD via a Field switch Isolator to a HVAC Fan motor. The motor is running at 130amps Full Load Current.
We are experiencing very high temps at this field Isolator and I was wondering if anyone has come across this issue before with this cable.
Many thanks,
Thomas
We are using a 4 * 50mm Olflex cable from a VFD via a Field switch Isolator to a HVAC Fan motor. The motor is running at 130amps Full Load Current.
We are experiencing very high temps at this field Isolator and I was wondering if anyone has come across this issue before with this cable.
Many thanks,
Thomas





RE: Olflex Cable Over-heating
The cable Olflex is a Lapp cable. I think is a Oil Resistant Motor Supply Cable for Large HP VFD Drives with UL & CSA TC Approval 3*1/0 AWG +8AWG.
According to Lapp catalog [see:]
http://www.lappusa.com/vfdselection.htm
For 50 hp motor 230 V FLC = approx. 130 A Lapp indicates this cable indeed.
As the core insulation is XLPE (cross linked polyethylene) the maximum temperature may reach 90 degree C[194 F].
If by "Field switch Isolator" do you mean an isolator [power] switch mounted on field then Field switch Isolator heating may be due to cable connection [ the cable lug is not properly fitted –in my opinion].
Also, if the cable is very warm indeed may be also a problem of the shield connection.
I think ,if there is no another problem, the shield has to be grounded only at one end.
Regards
RE: Olflex Cable Over-heating
Yes the field isolator is a switch for the motor before it enters the HVAC enclosure. I feel you are correct in suggesting the lugs. The Olflex I think is a type 7 stranded cable and I think the lugs used are for SWA which I think is a type 4 strand.
The high temps are occurring at the six connections of this Isolator. Would wrong lugs or crimps cause this problem?
Thanks,
Thomas
RE: Olflex Cable Over-heating
If there is somewhere an aluminum-copper contact between cable lug and conductor or cable lug and the switch pad may be another problem.
Regards
RE: Olflex Cable Over-heating
When we changed the Isolator we re-lugged the cable therefore a crimping issue would mean two different Electricians crimped incorrectly. We have been onto the cable supplier and they are recommending different lugs. See attached data sheet. I have been trying to find out from them what the diffrence is with the lugs we are using and the ones in this sheet as they look identical.
RE: Olflex Cable Over-heating
Sorry wrong data sheet. See file for Lug data sheet.
RE: Olflex Cable Over-heating
Secondly, I cannot open your second attachment and I cannot see the lug. It is possible this lug is also long-tongue and the contact area is bigger.
RE: Olflex Cable Over-heating
The cable is 4core 50mm so I reckon we are too small with the SWA lugs as you state. Its possible that the Electricains have had to cut out some strands to get the core into the lug. Would this causing arcing and overheating in your opinion.
I'll attach that pdf again.
Cheers,
Thomas