Tony S
Senior Member
- Location
- Resting under the Major Oak UK
You’ve just disillusioned me, I though they were the same the world over.
MOLDED CASE BREAKER KEEPS TRIPPING AFTER 8 HOURS
- Thread starter TrueRMS
- Start date
- Status
You’ve just disillusioned me, I though they were the same the world over.
kwired
Electron manager
- Location
- NE Nebraska
His (and mine) are publicly owned utilities, the people they serve are the investors, they are there to serve the customer (within reason) not to make huge profits.
kwired
Electron manager
- Location
- NE Nebraska
187 amps times .135 volts is a little over 25 watts being lost through the contacts, that is high enough that it should be of concern. That is just for the one pole that measures .135, if all three poles measured the same you are losing 75 watts in the breaker.
ptonsparky
Tom
- Occupation
- EC - retired
IIRC from previous threads anything over .1 volt is suspect. The additional .035 starts getting into meter accuracy and if you were holding your left foot just so, while taking the reading.
The 300 watts heat total is substantial, IMO. dependent on heater styles and if they were included in the readings.
Exercising the breaker most likely will reduce the contact resistance a Nd decrease the heating. Remember that the moving contacts actually rub slightly against the stationary contacts when there are closed together. In their lifetime most breakers are never opened and closed unless they happen to trip or to disconnect the circuit.
You would think that since the subject breaker has tripped a few time that should helped reduce any contact resistance if it's going to happen.
Saturn_Europa
Senior Member
- Location
- Fishing Industry
- Occupation
- Electrician Limited License NC
Any chance there is a SCADA system?
See if you can trend run command, run feedback, amps, etc....... Great troubleshooting tool.
See if you can trend run command, run feedback, amps, etc....... Great troubleshooting tool.
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
PFCC Banks Going Bad
PFCC Banks Going Bad
Great stories from you and Templdl.
I have a couple of my own.
The first one occurred many yrs ago at a large Telco data center in the area. The customer was experiencing random anomalies throughout the center; VFD's shutting down, breakers tripping, etc. As the problems continued and the with the events manually logged, a look at the Dranetz monitoring station showed that a voltage transient (micro seconds) was occurring on one of the phases of the incoming line (12KV entering the center, monitoring on the 480V side of one of the double-ended substations.) This voltage spike was occurring on the same phase at 6AM every morning. This was a Dranetz 658 so you could see the spike graphically on the sine wave. The cust was requested to send a letter (no email back then!) to the POCO with a copy of our findings for them to investigate. After about a month the anomalies and spikes disappeared and the cust received a letter back from the POCO thanking them for alerting them to a problem on their end; a faulty blade/ contact on one phase of one of their 12KV PFCC banks. Two problems solved at the same time.
The second one occurred in a nearby Telco central office.
We got an emergency call to investigate the loss of power to 37 rectifier modules (200A @ 480V) in (3) 48VDC plants. The building Telco equipment was operating on batteries while the rest of it was being powered by their backup generator. After our investigation and restoring the building back to normal (it was like watching the A-Team TV show in action with the help of numerous Telco employees grabbing spare modules throughout CA to the rescue with no service lost!) the root cause turned out to be a faulty PFCC bank on the POCO 12KV line. And yes I did speak to the POCO duty chief and he did admit that they changed out a bad PFCC bank earlier that morning that had a phase intermittently shorting to ground. For more info on the Striking Ground Phenomenon and the long version of this story see attached taken from our field report:
PS
just the equipment loss alone was est to be around $225,000.
PFCC Banks Going Bad
Great stories from you and Templdl.
I have a couple of my own.
The first one occurred many yrs ago at a large Telco data center in the area. The customer was experiencing random anomalies throughout the center; VFD's shutting down, breakers tripping, etc. As the problems continued and the with the events manually logged, a look at the Dranetz monitoring station showed that a voltage transient (micro seconds) was occurring on one of the phases of the incoming line (12KV entering the center, monitoring on the 480V side of one of the double-ended substations.) This voltage spike was occurring on the same phase at 6AM every morning. This was a Dranetz 658 so you could see the spike graphically on the sine wave. The cust was requested to send a letter (no email back then!) to the POCO with a copy of our findings for them to investigate. After about a month the anomalies and spikes disappeared and the cust received a letter back from the POCO thanking them for alerting them to a problem on their end; a faulty blade/ contact on one phase of one of their 12KV PFCC banks. Two problems solved at the same time.
The second one occurred in a nearby Telco central office.
We got an emergency call to investigate the loss of power to 37 rectifier modules (200A @ 480V) in (3) 48VDC plants. The building Telco equipment was operating on batteries while the rest of it was being powered by their backup generator. After our investigation and restoring the building back to normal (it was like watching the A-Team TV show in action with the help of numerous Telco employees grabbing spare modules throughout CA to the rescue with no service lost!) the root cause turned out to be a faulty PFCC bank on the POCO 12KV line. And yes I did speak to the POCO duty chief and he did admit that they changed out a bad PFCC bank earlier that morning that had a phase intermittently shorting to ground. For more info on the Striking Ground Phenomenon and the long version of this story see attached taken from our field report:
PS
just the equipment loss alone was est to be around $225,000.
Interesting, more PFCC issues,
And of course the POCO stepped up to the plate and took the hit, ya right. The only time that I had a POCO asume some of the cost for a loss was when they failed to advise d others hot line of a line that they barried WWTP addition. After call in diggers hotline the excavator started digging a trench dug up an underground feeder and single phased the plant. The POCO to my surprise assume a portion of the cost of some fried 3ph motors.
TrueRMS
Member
- Location
- Windsor Colorado
No SCADA its Ovation and only gets a running feedback
jrlelectric
Member
- Location
- Valencia California
jrlelectric
Member
- Location
- Valencia California
Obsolete Circuit Breaker Tripping
Obsolete Circuit Breaker Tripping
Back in the 80,s and 90's our business was selling and reconditioning Circuit Breakers. We only do New Now.
The vintage Circuit Breakers from the 50,s were so robust and had so much silver content in the contacts that they last forever but the trip units only last so long. Cleaning the contacts and making sure the wire connections are clean leaves only a couple of possibilities.
The most common is the contacts are pitted or have a buildup of dirt. If this just started and the ambiant temperature is very hot you can put a fan in front of the panel to hold you off. If you filed the contacts, it is important to make sure the stationary and movable contacts are a perfect match. We never filed contacts but the companies that did would put a piece of carbon paper between the contacts to look how much surface is a solid match.
If your wires are tight and it is tightly bolted to the busbar, the trip unit may be bad. These breakers have a bimetalic strip (2 different metal together that expand at different temperatures) causing them to bend and hit the trip bar. Depending on brand these are approx 16 inches long (KL Frame) or 20 Inches long (L Frame). If you need to replace the breaker and can do a plant shutdown, I can assist you to get custom mounting hardware and you can put a brand new or breaker you already have in its place.
I will be out until Monday 7/24. If you want the same breaker so you do not need to perform any magic, I can refer you to some excellent companies. We no longer do it. I wish you the best.
I do not know if leaving a plone number or e-mail is acceptable on this forum
Sincerely Joe
JRL Electric Supply
Obsolete Circuit Breaker Tripping
Back in the 80,s and 90's our business was selling and reconditioning Circuit Breakers. We only do New Now.
The vintage Circuit Breakers from the 50,s were so robust and had so much silver content in the contacts that they last forever but the trip units only last so long. Cleaning the contacts and making sure the wire connections are clean leaves only a couple of possibilities.
The most common is the contacts are pitted or have a buildup of dirt. If this just started and the ambiant temperature is very hot you can put a fan in front of the panel to hold you off. If you filed the contacts, it is important to make sure the stationary and movable contacts are a perfect match. We never filed contacts but the companies that did would put a piece of carbon paper between the contacts to look how much surface is a solid match.
If your wires are tight and it is tightly bolted to the busbar, the trip unit may be bad. These breakers have a bimetalic strip (2 different metal together that expand at different temperatures) causing them to bend and hit the trip bar. Depending on brand these are approx 16 inches long (KL Frame) or 20 Inches long (L Frame). If you need to replace the breaker and can do a plant shutdown, I can assist you to get custom mounting hardware and you can put a brand new or breaker you already have in its place.
I will be out until Monday 7/24. If you want the same breaker so you do not need to perform any magic, I can refer you to some excellent companies. We no longer do it. I wish you the best.
I do not know if leaving a plone number or e-mail is acceptable on this forum
Sincerely Joe
JRL Electric Supply
- Status