LV phase rotation 2

[Padlock01]

Hi guys, I am busy with a ship loader in Peru we have a 630kVA 440V TX on board, all the drives ,including conveyors, winches aux drives must turn clockwise except for one side of travel which should turn ant clockwise, instead of checking each motor can we not check the LV side of Transformer with a Phase Rotation meter and change there only. Thanks in advance.

 

[RonShap]

You can change only at the transformer, and you can reverse all at the same time.

It will be a little rough because you have a lot more wire at the main.

 

[crshears]

Is the ship loader on board the ship and designed to use shore power for its operation? If yes, the grunt work involved [as RonShap has observed] bolsters the argument for installing a permanent phase-rotation-swapping 3PDT switch on board in series with the shore connection right at the outset, during outfitting; the operating engineers and electricians will bless the designers and specifiers every time they use it...

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[ScottyUK]

Is this a temporary fix or a permanent one? Over here the convention is to make the swap at the motor so that the phase colours are true which makes mistakes less likely.

 

[Padlock01]

Hi Guys,
ScottyUK the Design is complete we are busy cabling up the electrical equipment \ the MV Switchgear board is fed via a trailing cable from a local substation and the 630kVA TX is on board the ship loader refer attached GA drawing its just that it would make life easier if we could change phase rotation to clockwise in one place instead of opening all the motor terminal boxes, I gather from some of the replies there should be no problem.

 

[waross]

We did a large pulp millproject and used that method with very good results. A,B,C, Red, Black, Blue, and left to right orientation in the motor control centers was carried through to all motors. The T1, T2, T3 desigantion on the motor leads was found to be completely accurate in predetermining the motor rotation.
The only problem was with about 6 or 8 motors fed from one small MCC. The MCC was arranged with A,B,C running from right to left instead of the normal left to right.
As I understand it, the ship loader will be permanently connected to shore power and you are looking for efficiency in the initial wiring of the machine.
Anecdote: A friend of mine did a similar project in that part of the world many years ago.
Back then it was common for the electrical super and the mechanical super to go together and bump each motor to check and correct the rotation. It was also common to bet a bottle of beer on each motor. It was normal for each to win about half of the beer. That evening they would get together to consume the beer.
My friend was able to check the rotation of one motor quite early in the project. He had his electricians follow through the color coding to each motor and connect each motor for the required rotation.
On commisioning day he won every beer. He declined to accept his winnings on the basis of special knowledge. The mechanical super replied that my friend had won the beer fairly and he would gladly pay up, but he wanted to know how it was done!
If your colleagues don't read this you may be able to win a few bets come startup day.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Electrically it will work fine with a swap at the source, it just won't be 'right'. As long as everyone understands what has been done and where then it should be OK.

One of my many pet hates is lazy electricians who make a phase swap at the MCC rather than the motor so (for example) power from the red phase busbar turns up on the blue conductor and vice-versa. It becomes horribly confusing when parts of the plant are wired to one convention and other parts are not.

 

[Padlock01]

Hi Guys,
Thanks for the input, Bill I will have to bet beers with my mechanical counterpart.ScottyUk, I agree that is the norm but I have this Mad German mechanical engineer who wants to cut down on commissioning time, But in his defence he knows the equipment, earlier during contruction the ship loaders boom winch VFD would not work so we used a temporary VFD without a braking resistor so we set the RPM @ 10rpm and used the manual brake lever for pressure for on and off controlling overspeed sometimes the brakes screamed but it took an hour to lower to 0 deg. "The Joys of Construction".