Any logical reason?

[YuriSarcas]

I am modifying an existing system with updated digital controls. It consist of three generators and a master. As I began going through the old drawings to find out how to connect the old wiring to the new wiring I discovered that sometime in the past 23 years someone rolled the sensing lines coming into the front of the switchgear. By this I mean the generator comes in ABC but all the voltage and current sensing lines go into the front at CBA. I have racked my brain and spoken with other colleagues and they see no logical reason for this.

I had to do one generator at a time, Get the new to run with the old and then move on to the next one. I had to wire the new the same way for the synch to work correctly. Once I am finished with all gens I plan to roll it back to the correct rotation unless I find out a reason to keep it that way.

Can anyone here come up with a viable reason as to why someone would do this?

Thanks.

 

[davidbeach]

If it works, why mess with it? Change simply for the sake of change is not generally a good thing.

 

[waross]

If there are or ever were feed throughs from the back to the front, they would be ABC on one side and CBA on the other side.

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

 

[YuriSarcas]

They physically swapped the control wires on the gen buss connections and CT secondary's. I verified this by the butt splices they put in because the factory wiring would not reach from C phase to A phase. They did this on the main buss sensing also. I have been working with switchgear for years and in my experience most of the time A phase buss goes to A phase metering. Unless of course the source is CBA.

I had to roll it back to ABC on the voltage regulator because it was showing negative kW when it was the only one on the buss with load. Talk about some crappy load share when I brought the other gen online in parallel...haha

I just don't understand why you would want your metering opposite of your source. It was analog before so I do not think it mattered much but with the digital stuff it tends to care on references.

 

[tinfoil]

Unfortunately, field wiring is often done by 'connect it, and if the rotation is wrong, just swap two phases. Now you're done'

Once the first thing has been done that way, it can get entrenched, and it may have been 'easier' to leave it thatg way rather than make it right later.

This is more common when only one guy is doing it all.