Message Board Thread - "Standard classifications of faults on electrical equipment"

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Standard classifications of faults on electrical equipment highgear 10/28/2009
Are there any standard classification of faults (i.e. delta T) for electrical equipment such as wiring. I doing a study on some extruder drives and am seeing some thermal gradients on main 480V conductors. Thanks in advance for any help.

Wade Youngblood
 
Re:Standard classifications of faults on electrical equipment highgear 10/28/2009
Here's an image I'm trying to classify...
 
Re:Standard classifications of faults on electrical equipment IRJay 10/28/2009
no, NFPA 70B gives general guidance. NETA has some delta temp guidance. I use NEC 310-13b table to relate max temp on an insulation type and determine my own fault levels.
 
Re:Standard classifications of faults on electrical equipment IRJay 10/28/2009
that image is not an insulation problem. It is a termination problem.
Run your delta to the other phases in roughly the same location, preferrably not on bare metal. My fault level is still the wire temp for that insulation class.
 
Re:Standard classifications of faults on electrical equipment RayRay 11/11/2009
Hi,
I modified the Military Standard for Electrical Equipment MIL-STB-2194.
I have used this for ~9 yrs with great success.
Comparing like components:
Priority 3, delta T 10 - 25 deg C.
Priority 2, delta T 25 - 40 deg C.
Priority 1, delta T => 40 de C.
I have found, even with a delta T of 10 deg C (and not exceeding the cable insulation max temp)on an electrical connection, lug, terminal block, etc... the problem is usual fixed by lubricating, cleaning and tightening the connection. I always perform a follow-up rescan after repairs have been made.

Ray G.
 
Re:Standard classifications of faults on electrical equipment Ladik 11/27/2009
highgear wrote:
re any standard classification of faults (i.e. delta T) for electrical equipment such as wiring. I doing a study on some extruder drives and am seeing some thermal gradients on main 480V conductors. Thanks in advance for any help.

Wade Youngblood
Hi Highgear.
You have to all slacken up first. Your previous advisers forgot to the main problem . The load. How many % load is your equipment from nominal load (100 %)? Because you have to always re-count delta T from your %load to delta T at nominal load (100%).It's just prediction of course not realy measured value ! So , first step : you use boxes area (rectangles), not spots.You put one box on "bad" phase and second box on "good" (better) phase. Second step : you determine delta T. Third step : you re-count "delta T corrected" at nominal load. Use math formulas... You remember that contact resister temperature is rising with quadrate of load % !
In U.S.Steel Slovakia (Europe)at switching room and bridge switching room as well as bredge trolley evaluation we use 3 levels.
Level 1 - delta T corrected < 10°C
Level 2 - delta T corrected 10°C - 100°C
Level 1 - delta T corrected > 100°C (for hhv - 60°C)
Sorry for my horrible english...
 


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