Inrush Current Carrying Capacity of Cable

The answer is either yes or no. If it is over- or correctly-sized, the answer is yes. If it is under-sized, then the answer is no.

The protocol for cable sizing for all eventualities is given, once again, in good ol' British Standard 7671, the repetition of which reminder is somewhat tiresome.

Weather Whether

YES.

...otherwise it isn't a cable; it's a fuse.

Given the information provided (no current, not time, no cable size, no cable length, no cable type, no installation information to calculate de-rating factors, no country of origin to reference local electrical standards,) my crystal ball says no.

Your a graduated Electrical Engineer (you say) and you cannot work this out or even post a question that has at least some information in it to allow someone else to give you an answer?

What did you study, Microprocessors or something?

Were you not taught during your education how to go and find the answers yourself? Books, internet, cable manufacturer websites, a simple internet search, self-learning?

You are NOT going to get a design engineer job in the oil and gas industry if you are asking questions like this. I wouldn't give you a job with peoples lives on the line based on your design decisions.

Take all this as an instructive prompt that you should perhaps re-evaluate your career and look into furthering your education and knowledge, be it self-learning (not asking us to hold your hand and teach you by the way) or an additional (and perhaps more practical) electrical course.

_{Jack - An actual Design Engineer working in the oil and gas industry (among other things)}

GA. This is the sort of stuff to be found in BS7671.

Oops! It has - time and again - been mentioned in this forum - by experts, that there is a huge difference between the starting current and the (magnetising) inrush current in motors.

The magnetising inrush current is necessary for excitation of the motor core & its magnitude can be as high as 10 to 12 times the rated motor current. And, its duration would typically be about 10 to 100 milli-seconds only (more for larger motors). Whereas, the starting current is the current required to accelerate the connected load from zero speed to rated speed,. Its magnitude would be between 5 to 8 times the rated motor current (when started direct-on-line). Its duration would depend upon the inertia of the motor's rotor and that of the driven equipment. It may vary from about 4 milliseconds for a small centrifugal pump to about 30 to 40 seconds for centrifugal blowers.

Now, coming to the short time withstand capacity of cables to tolerate this high current (either starting current or even the magnetising inrush current), the same may be verified by the adiabatic equation:

K²S² = I²t

where

K = Adiabatic Constant, depends upon the conductor & the insulation of the cable

S = Cross sectional area of the cable conductor, in sq.mm

I = Current, in Amps

t = Duration, in seconds

Now, for your expected high current, for the given cable, you may very well verify the withstand time.

Hope the above is clear!

Almost I forgot it:

See also:

IEEE-242/2001

Ch.9.5 Overload protection of cables

Dear 7anoter4!

Can u please shared to me IEEE std 242-2001 file. I'm looking for this std on internet long time but difficulty to get it.

Now i'm working in Mong duong II power plant project (located in Vietnam), in-charge protection relay system. So i need this file for studying.

If you're possible, please send to me via email address: dinhbka51@gmail.com

Thanks a lot!