Phase Reversal Provision in MPB

This sounds really, really weird. There should be no reason for the grid ("commercial side") to have inconsistent phase rotation. You should be able to test your own network, just once, with a phase protection relay or other instrument. If the rotations match, fine; if not, simply interchange two phases on your side.

It's down right bizarre, are you seriously saying the utility power reverses?

Sorry but I don't believe you.

in pakistan .. may be..

I'd love to see a reversing turbine or diesel gen set.

Who knows? Anything is possible! (In your imagination).

Lines go down, linesmen too rushed and/or too stupid to know how to reconnect them in the proper sequence.

Heck, I had that happen once in Washington State! Took out an entire sawmill (who also was too cheap to have Phase Reversal protection on critical equipment).

What I don't understand is how this is being corrected with ACBs, and why it makes a difference if it is YBR or BRY or RYB, they are all the same relative rotation, should not be an issue.

Yes it happens and happens many time it is the mistakes of line man/Cable Jointer cost us a huge amount and 30 hours power generation, Change the sequence many times but doesnt come to the "RYB" position. Finaly after 30 hours we acheived our target. We already have sequnce "RYB and YRB" with 2 seperate ACB's and we found it is very much difficult to cover all the sequence through ACB's. Yes it is Pakistan and acommon error is there.

It is a mandatory practice before carrying out any cable jointing/ overhead line conductor jointing work to test existing phase sequence of the system and repair works done accordingly complying with existing phase sequence.. In any case, if shifting of conductor(s) is not possible due conductor length, space constraints at the place of joint, cross conductor connection may be done but again,proper phase sequence must be checked and line connections should altered accordingly at the other end to have same phase sequence( source end and load end ). If the cable jointer does understand the method of checking of phase sequence and its importance in electrical power system, qualified supervisor must be present at time of work.

Manindra

Best is to have a phase sequence relay which will trip your incoming breaker instantaneously if there is phase reversal. You can then change it manually by reconnecting the incoming cable phases in the correct sequence. You will only have to ensure sufficint length of final tails to enable this exercise. This is a rare occurence and I have not seen this happen in my 48 years of experience in India and Middleeast.

All I can say is the cable must be rubbish if you have to have it repaired frequently. Overhead lines would be glaringly obvious if there are crossed phases.

Any cable jointing I've been involved in, phase orientation has been of paramount importance. I can't believe that a cable jointer wouldn't understand this.

Maybe I've been lucky with jointers.

I trained up to do jointing so that I understood it, in those days it was an art form. No hot or cold shrink, but oil impregnated tapes and plumbing metal.

What did it do? Unsaw some logs and put them back together?