×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Floating delta ground fault location

Floating delta ground fault location

Floating delta ground fault location

(OP)
Some of my stations still have floating delta 480 volt systems.  Last week I drove a thousand miles round trip to help a station I&E (more "I" than "E") technician locate a ground fault.

I hate to resort to the "turn off one circuit at a time and see when it goes away" method of fault location.  Installing a grounding transformer is not in the cards right now due to budgetary considerations.

At one time I had access to a ground fault locator for delta systems.  It basically took an ungrounded phase to ground through a resistor and a pulsing contactor so the fault could be located using a tong-type ammeter around all three phases of a branch circuit.

It's been too many years since I had my hands on that detector.  Does anyone know of a manufacturer for that sort of set, or do I have to build one myself?

old field guy

RE: Floating delta ground fault location

You can probably build it quicker than you can find it, oldfieldguy.  

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

RE: Floating delta ground fault location

In China they are  installing MV ungrounded systems and have developed a relay developed a system to detect faults.
Beaman would turn in his grave.
The system you describe is an old US method with a contactor that made the pulse through a 5 amp resistor. Powell may have something they could make up. If it was me I would contact http://www.selinc.com/ they are the cutting edge on relaying these days, they have a relay they use on medium voltage and may have something for low voltage.     

RE: Floating delta ground fault location

(OP)
Slava--

Thanks!  Now, does anybody have any experience with this unit?  the old things I used in the past used 10-20 amps of detection current.

old field guy

RE: Floating delta ground fault location

One question that bugs me here,  with 1000 mile round trip, why not fly?

RE: Floating delta ground fault location

(OP)
Steamdog--

Because by the time I got to the airport, got on a plane, flew through interconnecting stops to the closest airport to the destination, then rented a car and drove the the actual remote site, the time element would have been a wash.

In the cited case, I actually stopped by one of my other stations on the return trip, so I killed two birds with one stone.

I have a company car and a fuel card and a thousand miles of pipeline, 24 compressor stations including two offshore platforms (I fly to those)spread over four southern states.  Natural gas pipelines are terribly inconveniently located.

It's a fun job!  Kind of like a hobby with a paycheck.

old field guy

RE: Floating delta ground fault location

Actually, I like driving, too.  We are lucky in our area, being the Fisher rep we sell a lot of gas regs, but also being in the NYC metro area, there are not many miles to travel (but many hours in traffic!!)

RE: Floating delta ground fault location

Since you said 480V systems, the typical charging currents are around 1 - 2 amps. Basically depends on the length of the cables though.
Respectfully.

RE: Floating delta ground fault location

(OP)
Steamdog--

The only thing I have that is close to a city is a station northwest of Houston.  Twenty years ago it was out in the boondocks.  Now suburbia has flooded in around it.  Naturally the neighbors complaint loudly about the noise from our engines, no matter that the engines were there forty years before any of their houses.  the rest of my stations are out in the countryside, bucolic park-like locations.

Twiceburnt--

That sounds like my system.  One option I'm looking at going forward is a zig-zag grounding transformer, or maybe an wye/broken delta.  I have to see what fits in our (non-existent) budget.

old field guy

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources