Can we connect directly two busbar of MV switchgear with MV cable (same rating) 3

[putu_pjb]

Dear All,
We want to extend our MV switchgear. It is separated by a wall but still on the same floor.
Is it allowed to connect both busbars with cable? Cable's size and rating is the same as busbar
Busbar : Cooper, Three pole 7.2KV 1x80x10mm, 1250 A Single Busbar
Cable : 300 m2, N2XSEFGbY, copper.

Thank you

 

[davidbeach]

Probably depends more on applicable local code than anything to do with the actual physical characteristics.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[waross]

Under Canadian Code, it would be suitable subject to protection and installation requirements.
1. Protection; The protection ahead of the bus bars must be adequate to protect the cable. Local codes.
2. The cable must be installed in a suitable fashion and be of a type approved for the use.
A cable such as the feeder feeding the bus bars installed in the same way should be acceptable, but local codes apply.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[RRaghunath]

A rigid busbar supported by post insulators is much more reliable than a cable.
This means overall reliability of the switchgear reduces.
This is to be taken in to account and if no option, etreme care to be taken at glanding and termination cables to minimise the risk.
Also, you may consider providing busbar protection to isolate the busbar/cable quickly.

 

[putu_pjb]

thank you all for your feedback.
now we think about replace cables with a rigid bus bar install in a bus duct to connect both busbars.

 

[waross]

A device that is rated for an Available Short Circuit Current will be tested at a greater current at a fairly low power factor.
The Available Short Circuit Current is based on a symmetrical current. A fully offset, asymmetrical current peak may approach 2 x √2 of the RMS value. The magnetic forces are related to the peak current.
Be sure that your buss supports are adequate.
Years ago, Klockner Moeller published a series of time lapse photos of a set of bus bars breaking loose under fault current conditions.
The photos were memorable.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!