zog
Senior Member
- Location
- Charlotte, NC
How do you like that Phenix Brian? I was looking at one at a trade show and it looked nice.
Circuit Breaker Exercising Standard
- Thread starter spsnyder
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brian john
Senior Member
- Location
- Leesburg, VA
I own AVO, EIL and Phenix, the Phenix are acceptable and the newer models are WAY better that the early models. They are local which simplifies service.
I would like to point out that breakers respond to current so it doesn't matter what voltage is used.
Voltage is important when it comes to interrupting ratings, which is not an issue then testing a breaker's thermal response.
But I must caution that only thermal should be tested. If one even attempts to test a breakers instantaneous calibration there it is almost a given that the breaker will be damaged. There is no practical way to field test the magnetic calibration.
Voltage is important when it comes to interrupting ratings, which is not an issue then testing a breaker's thermal response.
But I must caution that only thermal should be tested. If one even attempts to test a breakers instantaneous calibration there it is almost a given that the breaker will be damaged. There is no practical way to field test the magnetic calibration.
zog
Senior Member
- Location
- Charlotte, NC
You are talking about MCCBS right?
brian john
Senior Member
- Location
- Leesburg, VA
While instantaneous high current testing does I would assume put stress on a CB, meggering and ductor testing shows little or no effects on the integrity of the CB (prior to and after high current testings). Kinda of hard to verify operation without testing. Second tis testing is typically completed during acceptance testing and 3-5 years after that.
Would a customer be better served by a CB that does not work or one that may be SLIGHTLY stressed with no visible or additional testing effects?
Would a customer be better served by a CB that does not work or one that may be SLIGHTLY stressed with no visible or additional testing effects?
Just how does one control the rate of rise or the duration of the current spike that be used to check the instantaneous trip of the breaker?
Then, is it possible to check the calibration?
As a former breaker application engineer I know what this test actually consists of and the testing equipment that is required to do these tests. I had the opportunity to sit a test bench in the warranty returns department of one of the largest MCCB manufacturers testing for the magnetic calibration of returned breakers.
If the rate of rise to long there is a gray area between where the breaker will trip thermally and where it trips magnetically. The contacts can be teased and damaged. I have seen on rare occasions where a breakers contacts teased and were weldedtogether do to a low level fault that was not quite long enough in duration to trip the breaker thermally but not of great enough magnitude to have tripped the breaker magnetically. This is extremely rare.
On mag only breaker the breaker can be overheated and damaged. The testers attempt to use a "ramp up" method on their attempt to find out the point where the breaker trips. In a real lab setting there is a procedure to allow time between current "shots" where a series on consecutive shots leads to damaging the breaker.
Then, is it possible to check the calibration?
As a former breaker application engineer I know what this test actually consists of and the testing equipment that is required to do these tests. I had the opportunity to sit a test bench in the warranty returns department of one of the largest MCCB manufacturers testing for the magnetic calibration of returned breakers.
If the rate of rise to long there is a gray area between where the breaker will trip thermally and where it trips magnetically. The contacts can be teased and damaged. I have seen on rare occasions where a breakers contacts teased and were weldedtogether do to a low level fault that was not quite long enough in duration to trip the breaker thermally but not of great enough magnitude to have tripped the breaker magnetically. This is extremely rare.
On mag only breaker the breaker can be overheated and damaged. The testers attempt to use a "ramp up" method on their attempt to find out the point where the breaker trips. In a real lab setting there is a procedure to allow time between current "shots" where a series on consecutive shots leads to damaging the breaker.
brian john
Senior Member
- Location
- Leesburg, VA
Temp, In my expierence (and I called 3 testing contractors I work with) I have not have heard of damage to MCCBs from testing in approved methods. Not saying you are just the expierence of techs. Typically these are one time shots no consecutive.
Additionally I am almost positive manufactures would prefer not to see field testing of any kind, less warranty issues. And yes I am aware of factory field services.
But I am open to any published information available.
Additionally I am almost positive manufactures would prefer not to see field testing of any kind, less warranty issues. And yes I am aware of factory field services.
But I am open to any published information available.
Nema Ab4
Nema Ab4
One time shot? What was the current peak and the rate of rise?
Or is it as simple as intentionally shorting the load side of the breaker to see if it trips, sort of pass or fail so to speak.
On numerous occasions I have referred to NEMA AB4 which is an excellent place to start when addressing the subject of field testing MCCBs, "Guide Lines for Inspection and Preventive Maintenance of Molded Case Circuit Breakers Used in Commercial and Industrial Applications."
I doubt if anybody has troubled themselves enough to obtain a copy of NEMA AB4 to review as it is too much work. It's more fun to theorize than to have a set standard as described in this publication. It's the best publication that I know of that addresses this issue. Even though NEMA AB4 does describe Guidelines in section 2, Inspection Procedures in Sec 3, Preventive maintenance in 4, Testing procedures in 4, field testing procedures in 5, and the testing on accessories in 6 this publication is either ignored or people just don't know about it.
It may cost a couple of bucks but it?s a great reference if anyone bothers to get a copy of NEMA AB4. My 1996 copy is about 1/8? thick consisting of 28 pages. It?s not over technical so most technicians and electrician should be able to understand it. It is presented as basically as practical.
Nema Ab4
One time shot? What was the current peak and the rate of rise?
Or is it as simple as intentionally shorting the load side of the breaker to see if it trips, sort of pass or fail so to speak.
On numerous occasions I have referred to NEMA AB4 which is an excellent place to start when addressing the subject of field testing MCCBs, "Guide Lines for Inspection and Preventive Maintenance of Molded Case Circuit Breakers Used in Commercial and Industrial Applications."
I doubt if anybody has troubled themselves enough to obtain a copy of NEMA AB4 to review as it is too much work. It's more fun to theorize than to have a set standard as described in this publication. It's the best publication that I know of that addresses this issue. Even though NEMA AB4 does describe Guidelines in section 2, Inspection Procedures in Sec 3, Preventive maintenance in 4, Testing procedures in 4, field testing procedures in 5, and the testing on accessories in 6 this publication is either ignored or people just don't know about it.
It may cost a couple of bucks but it?s a great reference if anyone bothers to get a copy of NEMA AB4. My 1996 copy is about 1/8? thick consisting of 28 pages. It?s not over technical so most technicians and electrician should be able to understand it. It is presented as basically as practical.
brian john
Senior Member
- Location
- Leesburg, VA
Temp Chill, If you ever bothered to read any of my post you'll see I am all for education...Ordered the Copy today.
As for testing MCCB's, Yes it is a go no go test to published curves. As I stated previously (and subject to change), at present this is the standard in many specs and when there is a MCCB issue testing resolves many unanswered questions.
Copy arrived reading now
As for testing MCCB's, Yes it is a go no go test to published curves. As I stated previously (and subject to change), at present this is the standard in many specs and when there is a MCCB issue testing resolves many unanswered questions.
Copy arrived reading now
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zog
Senior Member
- Location
- Charlotte, NC
Temp, you sure are quick to make assumptions about people, first you bash NETA specs
"I'm not personally sold entirely on what NETA promotes, as I'm not so sure where they got some of the information that they base their recommendations on." and "I don?t believe that NETA should be viewed and a standard."
when you obviously have not looked at them, guess what the NETA testing spec follows for MCCB's, wait for it... your beloved NEMA AB4 that you are assuming none of us have read. People that live in glass houses......
You have no idea how a field test is done, you are making all kinds of crazy assumptions about the test methods used when a qualified test tech is following the same standard you reference.
"I'm not personally sold entirely on what NETA promotes, as I'm not so sure where they got some of the information that they base their recommendations on." and "I don?t believe that NETA should be viewed and a standard."
when you obviously have not looked at them, guess what the NETA testing spec follows for MCCB's, wait for it... your beloved NEMA AB4 that you are assuming none of us have read. People that live in glass houses......
You have no idea how a field test is done, you are making all kinds of crazy assumptions about the test methods used when a qualified test tech is following the same standard you reference.
brian john
Senior Member
- Location
- Leesburg, VA
I downloaded the NEMA Standards Publication AB 4-2003.
And It references how to perform high current instantaneous test, I very well may have missed the DO NOT DO portion of the said publication as I am no speed reader (and I did just glance at AB 4-2003) Will delve into it deeper this evening.
Oh and I did testing in their headquarters building, not that that makes a difference but kinda ironic, Don't you think.
One item to keep in mind this is a publication by manufactures that might be a bit bias. Check out the section on Ductoring/DLOR/Millivolt drop/Micro-ohm testing.
And It references how to perform high current instantaneous test, I very well may have missed the DO NOT DO portion of the said publication as I am no speed reader (and I did just glance at AB 4-2003) Will delve into it deeper this evening.
Oh and I did testing in their headquarters building, not that that makes a difference but kinda ironic, Don't you think.
One item to keep in mind this is a publication by manufactures that might be a bit bias. Check out the section on Ductoring/DLOR/Millivolt drop/Micro-ohm testing.
Greetings Brian,
You had the opportunity to do testing at the Pittsburg facility too? Awesome!!
As far as NEMA AB4 being bias I can't see that it is as it seems reasonable to me. But I do appreciate this discussion an to see your point of view.
If one were to look at it from a warranty point of view the person doing the field testing better have their ducks as the warranty request will be rejected if it passes testing back at the ranch. If not, not credit or replacement.
When out of warranty the person or business that is paying for field-testing places their confidence with the firm doing the testing. Replacing a product when it has been concluded to be defective benefits both the tester gets paid to replace the device as well as the manufacturer who sells more product. As such we must be very careful to use testing procedures that are in fact relevant instead of a set of rules that make it easy for a unqualified person to simply judge a device good or defective.
What is the section that you are referring to on Ductoring/DLOR/Millivolt drop/Micro-ohm testing?
I don't believe it's in my1996 edition.
Zod appears to be a bit crass by insinuating that I am "bashing" NETA. I have a problem with innuendoes and vague descriptions. I also question what NETA's basis for MCCB testing is and how it is performed in the field. NEMA AB4 has been around a bit longer than NETA. Do I have to be a NETA member to have access to their MCCB testing procedure to review? Or, Zod could describe the testing procedure and how it is done. It would be interesting if Zod were to compare the NETA test procedures with those as included in NEMA AB4 and describe the deference?s, why one is better than the other.
Most are not aware as to what a manufacture must to obtain and maintain a UL listing. From mechanical life tests, interrupting tests, to calibration tests etc. to assure that there are specific testing conditions that must be complied with. I know what these tests are and why they are done the way they are done.
It is a bit intriguing when field tests that are fraught with many variables challenge those which must be done by the MCCB manufacture who must test under a very specific set of standards. UL arrives unannounced to inspect manufacturing procedures and it is not that uncommon for them to pull a listing it a product does not comply shutting down a production line dead in the water. You don't mess with UL.
NEMA AB4 provides consistency to field-testing. If one reviews it I can't see where it would favor the breaker manufacturer. It provides a procedures to do an inverse-time current trip test which somewhat follows that which is required to do a UL calibration test I does take into consideration the variables that are present in field testing. It is not meant to do a calibration test but is done a 300% of the breakers rated current at which the breaker should trip within a range of time.
Instantaneous overcurrent trip test is also described, both run-up and pulse methods.
Using the run-up method one is cautioned about the damage that can be done to the testing equipment. Then there's the challenge of having a meter that can capture the reading of the current when the breaker does trip.
The pulse method is more accurate if done properly but the type of waveform and what part of the waveform the breaker is pulsed.
In addition, contact resistance is not a true indication of the health of a breaker. It may be meaning less or may be an indicator that one should take a closer look.
There are 2 things that affect resistance readings
1) The resistance is often measured using very low voltage such with a digital multimeter. The higher the resistance the greater the voltage drop across the contacts the more heating. A milivolt drop test conducted on an energized breaker would be a better indicator of what the contact resistance is under operating conditions. Remember that contact resistance=heat. But this must not be misinterpreted as a loaded breaker does generate heating watts. That also brings up the issue of when we expect something to be cool to the touch and it?s warm it is often referred to as being hot.
2) The moving contact does not simply close against the stationary contact but is rubs against it. What this means is that the contact resistance often changes each time you open and reclose the breakers. This is also where exercising a breaker can be of benefit as was the subject of the first post.
As far as NETA is concerned I think the organization provides a common set of guidelines which members apply for consistency which is a good thing, something that has been needed. But being a card carrying NETA member also brings the responsibility of common sense as a skilled professional having training in and understands electrical distributions protection and control systems as well as in safe electrical practices and procedures and knowing that testing is not necessarily a black and white issue.
You had the opportunity to do testing at the Pittsburg facility too? Awesome!!
As far as NEMA AB4 being bias I can't see that it is as it seems reasonable to me. But I do appreciate this discussion an to see your point of view.
If one were to look at it from a warranty point of view the person doing the field testing better have their ducks as the warranty request will be rejected if it passes testing back at the ranch. If not, not credit or replacement.
When out of warranty the person or business that is paying for field-testing places their confidence with the firm doing the testing. Replacing a product when it has been concluded to be defective benefits both the tester gets paid to replace the device as well as the manufacturer who sells more product. As such we must be very careful to use testing procedures that are in fact relevant instead of a set of rules that make it easy for a unqualified person to simply judge a device good or defective.
What is the section that you are referring to on Ductoring/DLOR/Millivolt drop/Micro-ohm testing?
I don't believe it's in my1996 edition.
Zod appears to be a bit crass by insinuating that I am "bashing" NETA. I have a problem with innuendoes and vague descriptions. I also question what NETA's basis for MCCB testing is and how it is performed in the field. NEMA AB4 has been around a bit longer than NETA. Do I have to be a NETA member to have access to their MCCB testing procedure to review? Or, Zod could describe the testing procedure and how it is done. It would be interesting if Zod were to compare the NETA test procedures with those as included in NEMA AB4 and describe the deference?s, why one is better than the other.
Most are not aware as to what a manufacture must to obtain and maintain a UL listing. From mechanical life tests, interrupting tests, to calibration tests etc. to assure that there are specific testing conditions that must be complied with. I know what these tests are and why they are done the way they are done.
It is a bit intriguing when field tests that are fraught with many variables challenge those which must be done by the MCCB manufacture who must test under a very specific set of standards. UL arrives unannounced to inspect manufacturing procedures and it is not that uncommon for them to pull a listing it a product does not comply shutting down a production line dead in the water. You don't mess with UL.
NEMA AB4 provides consistency to field-testing. If one reviews it I can't see where it would favor the breaker manufacturer. It provides a procedures to do an inverse-time current trip test which somewhat follows that which is required to do a UL calibration test I does take into consideration the variables that are present in field testing. It is not meant to do a calibration test but is done a 300% of the breakers rated current at which the breaker should trip within a range of time.
Instantaneous overcurrent trip test is also described, both run-up and pulse methods.
Using the run-up method one is cautioned about the damage that can be done to the testing equipment. Then there's the challenge of having a meter that can capture the reading of the current when the breaker does trip.
The pulse method is more accurate if done properly but the type of waveform and what part of the waveform the breaker is pulsed.
In addition, contact resistance is not a true indication of the health of a breaker. It may be meaning less or may be an indicator that one should take a closer look.
There are 2 things that affect resistance readings
1) The resistance is often measured using very low voltage such with a digital multimeter. The higher the resistance the greater the voltage drop across the contacts the more heating. A milivolt drop test conducted on an energized breaker would be a better indicator of what the contact resistance is under operating conditions. Remember that contact resistance=heat. But this must not be misinterpreted as a loaded breaker does generate heating watts. That also brings up the issue of when we expect something to be cool to the touch and it?s warm it is often referred to as being hot.
2) The moving contact does not simply close against the stationary contact but is rubs against it. What this means is that the contact resistance often changes each time you open and reclose the breakers. This is also where exercising a breaker can be of benefit as was the subject of the first post.
As far as NETA is concerned I think the organization provides a common set of guidelines which members apply for consistency which is a good thing, something that has been needed. But being a card carrying NETA member also brings the responsibility of common sense as a skilled professional having training in and understands electrical distributions protection and control systems as well as in safe electrical practices and procedures and knowing that testing is not necessarily a black and white issue.
zog
Senior Member
- Location
- Charlotte, NC
"I don?t believe that NETA should be viewed and a standard."
NETA ATS and MTS are standards recoginized by ANSI.
"I also question what NETA's basis for MCCB testing is and how it is performed in the field. NEMA AB4 has been around a bit longer than NETA."
I already told you the NETA standard is based on the NEMA AB4
"It is not meant to do a calibration test but is done a 300% of the breakers rated current at which the breaker should trip within a range of time."
Same as NETA
"In addition, contact resistance is not a true indication of the health of a breaker. It may be meaning less or may be an indicator that one should take a closer look."
Thats why NETA (like the NEMA spec) has no set acceptable value for contact resistance, the only spec is if one phase is >50% higher than the lowest phase, then investage further.
"There are 2 things that affect resistance readings
1) The resistance is often measured using very low voltage such with a digital multimeter. "
Not sure who would ever use a mutimeter for contact resistance, not acceptable test per NETA standards. NETA requires at least a 10A output microohmeter or millivolat drop test as you described.
"But being a card carrying NETA member also brings the responsibility of common sense as a skilled professional having training in and understands electrical distributions protection and control systems as well as in safe electrical practices and procedures and knowing that testing is not necessarily a black and white issue."
I could not agree more
You are the one making assumptions that you know more about breaker testing than any of us, how many tests have you actually performed yourself per NEMA AB4? For me, and I would guess Brian too, it is in the thousands of breakers.
One last quote "Do I have to be a NETA member to have access to their MCCB testing procedure to review? "
No you dont you can download it at www.netaworld.org i suggest you actually read this standard before you say anything else negative about it, following your own advice in your earlier post.
NETA ATS and MTS are standards recoginized by ANSI.
"I also question what NETA's basis for MCCB testing is and how it is performed in the field. NEMA AB4 has been around a bit longer than NETA."
I already told you the NETA standard is based on the NEMA AB4
"It is not meant to do a calibration test but is done a 300% of the breakers rated current at which the breaker should trip within a range of time."
Same as NETA
"In addition, contact resistance is not a true indication of the health of a breaker. It may be meaning less or may be an indicator that one should take a closer look."
Thats why NETA (like the NEMA spec) has no set acceptable value for contact resistance, the only spec is if one phase is >50% higher than the lowest phase, then investage further.
"There are 2 things that affect resistance readings
1) The resistance is often measured using very low voltage such with a digital multimeter. "
Not sure who would ever use a mutimeter for contact resistance, not acceptable test per NETA standards. NETA requires at least a 10A output microohmeter or millivolat drop test as you described.
"But being a card carrying NETA member also brings the responsibility of common sense as a skilled professional having training in and understands electrical distributions protection and control systems as well as in safe electrical practices and procedures and knowing that testing is not necessarily a black and white issue."
I could not agree more
You are the one making assumptions that you know more about breaker testing than any of us, how many tests have you actually performed yourself per NEMA AB4? For me, and I would guess Brian too, it is in the thousands of breakers.
One last quote "Do I have to be a NETA member to have access to their MCCB testing procedure to review? "
No you dont you can download it at www.netaworld.org i suggest you actually read this standard before you say anything else negative about it, following your own advice in your earlier post.
Thanks Zog.
Now we got the discussion off of dead center just as I intended.
I believe that we now have a common ground for discussing beaker testing.
Methods for checking contact resistance are misunderstood and, even when done properly can be misinterpreted.
I do respect those who want to discuss and application problem and have their ducks in a row, who understand and appreciate their issue. From my perspective there are all too many that don't have a clue and are looking for black and white answers that simplifies things into pass and fail.
One of my biggest problems is with those who ask questions in a way that they will get the answer that they want to hear which supports their conclusion. I have had to do a lot of detective work by asking a lot of questions when I suspect that there is more to the story.
I've gotten a few people quite irritated with we when I was persistent enough to get to the bottom of an application issue and they finally saw the light. I am the first to say that I have learned a lot in the same way.
Now we got the discussion off of dead center just as I intended.
I believe that we now have a common ground for discussing beaker testing.
Methods for checking contact resistance are misunderstood and, even when done properly can be misinterpreted.
I do respect those who want to discuss and application problem and have their ducks in a row, who understand and appreciate their issue. From my perspective there are all too many that don't have a clue and are looking for black and white answers that simplifies things into pass and fail.
One of my biggest problems is with those who ask questions in a way that they will get the answer that they want to hear which supports their conclusion. I have had to do a lot of detective work by asking a lot of questions when I suspect that there is more to the story.
I've gotten a few people quite irritated with we when I was persistent enough to get to the bottom of an application issue and they finally saw the light. I am the first to say that I have learned a lot in the same way.
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