Browse  |   Placement Papers  |   Company  |   Code Snippets  |   Certifications  |   Visa Questions Post Question  |   Post Answer  |   My Panel  |   Search  |   Articles  |   Topics  |   ERRORS new

 Categories >> Engineering >> Electrical Engineering

 Civil Engineering Interview Questions (3072) Mechanical Engineering Interview Questions (3287) Electrical Engineering Interview Questions (13323) Electronics Communications Interview Questions (2364) Chemical Engineering Interview Questions (416) Aeronautical Engineering Interview Questions (77) Bio Engineering Interview Questions (17) Metallurgy Interview Questions (79) Industrial Engineering Interview Questions (163) Instrumentation Interview Questions (2375) Automobile Engineering Interview Questions (106) Mechatronics Engineering Interview Questions (38) Marine Engineering Interview Questions (43) Power Plant Engineering Interview Questions (75) Engineering AllOther Interview Questions (1195)
Question
`what is derating factor in Cable ? how we minimise this?`
Question Submitted By :: Electrical-Engineering
I also faced this Question!!     Answer Posted By

# 1
Derating factor depends on ambient temperature & how u r
laying the cable ie., in Air,Duct,Burried.
normally the current carring capacity of a perticular cable
is calculated at 40*c, but if u lay the cable in air then
it includes the temparture around it,if it increases more
the 40*c then the conductor gets heated up by increasing
the resistance in it thus the current carring capacity of a
given cable decreases, so we will derate the cable

 Is This Answer Correct ? 151 Yes 18 No
Kekshavanarayana.g

# 2
Apart from higher ambient temperature than 40 degree which
derate cable, the depth of cable for UG Cable, distance
between two parallel cables also derate cable.

 Is This Answer Correct ? 56 Yes 12 No
Dkmathur

# 3
type of derating factor:
1-soil thermal resistivity
2-grouping factor(cable distrubtion in trays horizontial
-verticals)
3-temp derating factor
4-burial depth derating factor

 Is This Answer Correct ? 41 Yes 6 No
Helwan University

# 4
Die electric factor depends on the temperature around the
cable, method of cable laying etc..if cable is to be design
for 35 deg c and if temperature increases above 35 deg c
then resistance of cable increases (positive temp.
coefficient), so its current carrying capacity will
decreses...So current paseed through cable will decreases,
it menas its capacity will down..it's called derating
current and notrated current...and same effect is done for
cable laying method...By using good insulation and proper
method of cable laying reduces its effect...

 Is This Answer Correct ? 26 Yes 9 No
Shvetang Dave

# 5
derating factor depents on withstand level of ambient
tempreature,when it increase at tat time resistance of
cable is increase so current carrying capacity of cable is
decrease so it will derate the cable rating..
then based on the cable fixed in a cable tray and the
distance between the cable in tray...

 Is This Answer Correct ? 28 Yes 13 No
Dev Bala

# 6
Derating factor =Derated current capacity/cable ampacity

derating facor depends upon :- Ambient temp.
grouping of cable
thermal resistivity of soil
depth of laying.

 Is This Answer Correct ? 19 Yes 4 No
Lakhwinder Singh

# 7
Derating factor of cable is depends upon following factor

1)Cable laying depth
2)Ambient temperature
3)Ground temperature
4)Parallel cable distance

 Is This Answer Correct ? 13 Yes 4 No
Amit

# 8
Answer 9 is the most comprehensive...
U get loads of standards based on the country u r in..
If in duct-
1) Soik Thermal resistivity : Basically the max temp in the
surrounding. 40*C is the standard.

2) Conductor grouping : Due to arrangement of multiple
conductors there is a development of an EM field which
opposes the flow and thus we need to consider this factor.

3) Temp. Derating Factor : In this the arrangement of cables
in a conduit is of prime importance. It should be in such a
way that all cables have a minimum space to dissipate heat
into the surroundings. The cables can touch each other but
anyone cable should not be fully surrounded by other cables.

4) Burial Depth : Depends on the length below ground where
the conduit is laid.

 Is This Answer Correct ? 3 Yes 1 No

# 9
Loss of Dielectric strength of cable is the derating factor
of cable.... It can be minimized by selecting the proper
rating of cable with operating conditions and proper
maintenance of cables

 Is This Answer Correct ? 17 Yes 17 No

# 10
The cable derating factor is the reduction from its present
capacity for a certain gradual amount due to intermittent
ambient temperature, insufficient space, unbalance flux,
higher voltage dropped, depreciation, etc.

To minimize the cause and effect conduct proper survey and
proper wiring to withstand on the cable loads and locations.

 Is This Answer Correct ? 0 Yes 0 No
Realas

  Question Asked @ Answers Other Electrical Engineering Interview Questions how much distance is required for earth pit to earth pit in substation??? Divis-Laboratories 3 what is main advantage if motor connected in star or delta? Essar 3 Why substation battery room is coulered black? 1 How can i check a relay good or not? 2 What is battery Amphere-hour? How the battery back up time period is calculated? 2 how can we connect the capacitor bank to improve the power factor? 5 How much RPM in Turbocharger in Diesel engine. MAHINDRA 7 Can the efficiency of transformer be measured with the help of wattmeter readings taken at primary and secondary side? Support the answer. 2 how can we calculate cable size 1 Hi My Dear All Friends, There is one question it is widely used in Power Project's High Voltage Engineering. Question- What is the diffrence between Earth fault and Back up Earth Fault....???? . . . . . . Have A Good Day 1 What will be the direction of rotation of a Alternator in case it goes in motoring action when connected with grid ? NTPC 6 If we know the load for generator in KW then how it will be change to amps and also if we know the load in amps how it will change in KW and what Generator is good for that...suppose load is 500 amps 3phase......?? 1 For more Electrical Engineering Interview Questions Click Here