Old Pringle GFI Problem
- Thread starter laidman
- Start date
- Status
charlie tuna
Senior Member
- Location
- Florida
Re: Old Pringle GFI Problem
when was the last time this switch was tested? i believe they are supposed to be tested every seven years. a thirty five year old ground fault relay may be going bad or out of calibration. this would be the first step i would take in solving the problem..... too many operations of this switch can cause the mechinism to fail also!
when was the last time this switch was tested? i believe they are supposed to be tested every seven years. a thirty five year old ground fault relay may be going bad or out of calibration. this would be the first step i would take in solving the problem..... too many operations of this switch can cause the mechinism to fail also!
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Old Pringle GFI Problem
It's possible. Have the harmonics only recently appeared on your system? Did you recently install a large computer system, for example? Did the onset of the nuisance trips occur around the same time as the new installation?
If none of these are applicable, then it is also possible that the GFI device has reached its end of life. I would not hang my hat on that possibility, however.
Most of what we call "nuisance trips" are not really "nuisance trips.? I use that term to mean that something tripped unnecessarily, that no real failure has occurred, and that the trip device responded to something that did not really happen. In reality, however, most trips occur because something really did fail. We can?t always figure out what it was that had failed, but it is seldom right to place the blame on a failure of the trip device itself.
It's possible. Have the harmonics only recently appeared on your system? Did you recently install a large computer system, for example? Did the onset of the nuisance trips occur around the same time as the new installation?
If none of these are applicable, then it is also possible that the GFI device has reached its end of life. I would not hang my hat on that possibility, however.
Most of what we call "nuisance trips" are not really "nuisance trips.? I use that term to mean that something tripped unnecessarily, that no real failure has occurred, and that the trip device responded to something that did not really happen. In reality, however, most trips occur because something really did fail. We can?t always figure out what it was that had failed, but it is seldom right to place the blame on a failure of the trip device itself.
brian john
Senior Member
- Location
- Leesburg, VA
Re: Old Pringle GFI Problem
Depending on the type of ground fault relay depends on the problem. 35 year old pringles usually had dash pot with a ground return strap CT.
Is this a CBC type pringle? or linear motor operator type.
Early generation electronic GFI relays have fault problems as they age, some had problems with surges, the over voltages would activate the relay and trip the switch, others relays fail and seem (in my experience) to fault to the lowest current setting.
Is there neutral ground current.
Does the neutral ground current exceed the setting of the relay.
Has the pringle been serviced lately.
are there other protective devices blown fuse trip, single or under voltage trip.
Is rthere construction work going in in the building ( YES ELECTRICIANS STILL TRIP CIRCUITs TRYING TO LOCATE THE SOURCE CB or accidentlly)
Has the relay and CT been tested?
Has the switch been serviced per pringles recommendations at a maximum every three years.
And While harmonics are always a question IN MY EXPIERENCE most likely not the cause, but always a good place to put the blame.
Depending on the type of ground fault relay depends on the problem. 35 year old pringles usually had dash pot with a ground return strap CT.
Is this a CBC type pringle? or linear motor operator type.
Early generation electronic GFI relays have fault problems as they age, some had problems with surges, the over voltages would activate the relay and trip the switch, others relays fail and seem (in my experience) to fault to the lowest current setting.
Is there neutral ground current.
Does the neutral ground current exceed the setting of the relay.
Has the pringle been serviced lately.
are there other protective devices blown fuse trip, single or under voltage trip.
Is rthere construction work going in in the building ( YES ELECTRICIANS STILL TRIP CIRCUITs TRYING TO LOCATE THE SOURCE CB or accidentlly)
Has the relay and CT been tested?
Has the switch been serviced per pringles recommendations at a maximum every three years.
And While harmonics are always a question IN MY EXPIERENCE most likely not the cause, but always a good place to put the blame.
friebel
Senior Member
- Location
- Pennsville, N.J.
Re: Old Pringle GFI Problem
I recalled a problem that we had with a Pringle Switch. Every time that we had a damp day due to rain, etc. the fuse would blow.
I insisted that that the First-line supervisor use a Biddle-Megger to check it out. They could never find any bad readings with the Megger.
The first-line supervisor wanted to use the Hy-Pot tester, but I would always would say No, do not use the Hy-Pot, because it could be a destructive test. Well to make a long-story short.
One day the fuse blew, and I was not around, and the first-line supervisor used the Hy-Pot tester and he found the problem. The problem that he found was a tracking on the bakelite slate that the Pringle Switch was mounted, and every time that we had damp weather, the 600 volts would track on that path to ground, and blow the fuse.
They scraped and cleaned the carbon path to ground and put the switch back on line. Then they ordered a new bakelite slate for the Pringle Switch.
I recalled a problem that we had with a Pringle Switch. Every time that we had a damp day due to rain, etc. the fuse would blow.
I insisted that that the First-line supervisor use a Biddle-Megger to check it out. They could never find any bad readings with the Megger.
The first-line supervisor wanted to use the Hy-Pot tester, but I would always would say No, do not use the Hy-Pot, because it could be a destructive test. Well to make a long-story short.
One day the fuse blew, and I was not around, and the first-line supervisor used the Hy-Pot tester and he found the problem. The problem that he found was a tracking on the bakelite slate that the Pringle Switch was mounted, and every time that we had damp weather, the 600 volts would track on that path to ground, and blow the fuse.
They scraped and cleaned the carbon path to ground and put the switch back on line. Then they ordered a new bakelite slate for the Pringle Switch.
Re: Old Pringle GFI Problem
Thank you for the responses. I believe the switch is a CBC. When they tested it I believe the tech did the test incorrectly as we found a manual with the correct test procedure. It called for 38 turns of #14 around the GFI set with a variac for 7 amps giving it a fault current of 266A the tech used 120 turns giving the fault current at 120 times 7 ampere turns or 840A of fault current. we will check again this weekend. They are going to replace the GFI with the same unit. my question is should this be updated.
Thank you for the responses. I believe the switch is a CBC. When they tested it I believe the tech did the test incorrectly as we found a manual with the correct test procedure. It called for 38 turns of #14 around the GFI set with a variac for 7 amps giving it a fault current of 266A the tech used 120 turns giving the fault current at 120 times 7 ampere turns or 840A of fault current. we will check again this weekend. They are going to replace the GFI with the same unit. my question is should this be updated.
brian john
Senior Member
- Location
- Leesburg, VA
Re: Old Pringle GFI Problem
Pringle still manufactures the CBC and parts are available. As for the GF relay, this depends on the type of relay. If the relay is still available from the manufacture there should be no problem with replacing like with like.
The way we test the relay is utilizing a high current test set. we test for current pick up at all factory presets for current and time testing at 150% of the as found setting for current. A Pringle CBC with the GF relay set for time at .1 seconds should trip around .125 seconds any longer may be indicative of a switch operational problem, contact adjustment or lubrication problem.
The service/test should be comprised of a service of the switch, lubricating (LIGHTLY) the stationary and movable contacts/blades with an approved grease, micro-ohm/ductor/DLRO measurements of the power contacts and meggering (high potential) testing of the switch line to load, pole to pole, line and load and if this is a main switch neutral to ground with the neutral disconnect link removed, and the GF test as noted above.
On this switch contact resistance is (as with most high current devices) critical to operation.
Pringle still manufactures the CBC and parts are available. As for the GF relay, this depends on the type of relay. If the relay is still available from the manufacture there should be no problem with replacing like with like.
The way we test the relay is utilizing a high current test set. we test for current pick up at all factory presets for current and time testing at 150% of the as found setting for current. A Pringle CBC with the GF relay set for time at .1 seconds should trip around .125 seconds any longer may be indicative of a switch operational problem, contact adjustment or lubrication problem.
The service/test should be comprised of a service of the switch, lubricating (LIGHTLY) the stationary and movable contacts/blades with an approved grease, micro-ohm/ductor/DLRO measurements of the power contacts and meggering (high potential) testing of the switch line to load, pole to pole, line and load and if this is a main switch neutral to ground with the neutral disconnect link removed, and the GF test as noted above.
On this switch contact resistance is (as with most high current devices) critical to operation.
- Status