Short-Circuit and Device Coordination Programs

[bfletcher]

Do any of you out there do Short-Circuit and Device Coordination Studies and if so, what program (software) do you use? Pros and Cons on the software package? Just gathering information to make an informed decision. Thanks and have a great weekend.

 

[ronmath]

We use SKM Power Tools, seems to work good, though not very intuitive to learn.

 

[charlie b]

We also use SKM. I don't know if its the cheapest offering, nor the easiest. And it is a bit counter-intuitive, with regard to the use of the mouse in adding or moving components. But I got used to it in short order.

 

[dahualin]

I am an electrical engineer doing electrical system design for new building projects, renovation projects. And I have never done any short circuit and coordination studies. The only thing I have done may related to this is short circuit current calcuation to calcuate available short circuit from power source at each panel location so that we can design panel schedule with right AIC rating.

I understand the benefit of doing short circuit and coordination study. I am curious about which AHJ requires this kind of studies and what kind of clients require this kind of studies and what code requires this kind of studies. I have heard about OSHA requires Arc Flash study. Thanks.

 

[ron]

We use SKM and have done so for approx 15 years.

David,
The program helps calculate complicated systems that have many panels and sources. AHJ's require it for elevators and life safety emergency systems. Clients require it for reliability and setting of adjustable OCPD's.

 

[jim dungar]

I am curious about which AHJ requires this kind of studies ...

The state AHJ's in both Wisconsin and Minnesota require selective coordination per NEC 700 & 701 for all installations. I have done these studies for churches and school buildings.

 

[VxA]

We use SKM Power Tools, seems to work good, though not very intuitive to learn.

We also use SKM, and I agree with ronmath re the ease of use.

 

[Pierre C Belarge]

AHJs require it......

AHJs require it......

I am not attacking anyone here, I am very curious about the "AHJ" aspect of this thread.


First, I know that AHJ and its meaning varies from jurisdiction to jurisdiction.
Second, I will respond with what I experience in NY (which is sometimes just a joke...hence my interest in this aspect of the thread)

I am going to reiterate I am not picking on, or intending malice towards anyone, especially the guys here.


I completely understand the value of the Studies being required and performed. I also understand that the results may not always be the same, it depends on who is doing them, with what program, based on different methods.

So, for the engineers on this thread, when you mention the studies are performed for the AHJs, who do you really mean?

Where my interest comes in. I am an inspector. If you were to present me with the results of your study, most likely I would pass it on to the building department and put a copy in the job folder.
I can tell you I would not be comfortable in judging whether or not the results of the study were/are accurate.
I can also tell you that there is maybe 1 or 2 jurisdictions in the 3 counties (approximately 85 jurisdiction) that have the staff to look at and understand the results of the study.

So who is really looking at the results of your studies?
Is it really a 'chip' the building departments put away for the future, if something should go wrong with the engineering of that particular job?

 

[jim dungar]

So who is really looking at the results of your studies? Is it really a 'chip' the building departments put away for the future, if something should go wrong with the engineering of that particular job?

In Wisconsin. if a 'local' inspector cannot identify that a submitted report does not meet the selective coordination requirements they get the 'state' inspector involved. I have conducted short seminar sessions for the state department of facilities and local EI chapters. the consensus has been that it is actually easy to see if devices do coordinate (i.e. no overlap of device trip curves). For those devices whose coordination is not readily apparent the report must include a written explanation of why they actually do (i.e. reference to a fuse ratio table). Any time there is a lack of coordination the owner must apply for code 'variance'.

 

[ron]

Pierre,
The few times I've been asked for the curves, I believe it was only for the file.

 

[msteiner]

I perform short circuit, coordination, and arc flash studies using SKM. The short circuit studies are done on almost every job to verify AIC ratings of equipment that we're specifying, while the study itself is rarely submitted as a deliverable on those jobs. But industrial clients are the ones typically asking for coordination and arc flash studies, and they are very interested in the details of the study report.

As to the original question, SKM is pretty easy to learn, but I find it to be "clunky" in many respects. Lots of bugs that should have been worked out by now, a tendency to lock up and need to be restarted, and not entirely user friendly like other Windows-based programs. But it's the only electrical analysis software I've used, and I would recommend it. Very powerful.

 

[mayanees]

Waaaaaaaaahhhh!!!

Waaaaaaaaahhhh!!!

As to the original question, SKM is pretty easy to learn, but I find it to be "clunky" in many respects. Lots of bugs that should have been worked out by now, a tendency to lock up and need to be restarted, and not entirely user friendly like other Windows-based programs. But it's the only electrical analysis software I've used, and I would recommend it. Very powerful.

WAAAAAAAAHHHH !!!

He finds it clunky!!!! It locks up and needs to be restarted... WAAAAAAHHHH!!!

LOL Relax moderators, this is a friend who I'm bustin' on!

Not to sound too much like an old fart here, but I remember the days of hand calcs for studies.. the things that locked up were the brain and the wrist.
Then came SKM DOS, which got the job done, but you wanna see clunky???? It would crash every 20 minutes, so you learned to save enery 15.

But to speak to msteiner's complaint, I agree that in this day and age, one would not expect the amount of hiccups you get with SKM.

I will say in defense of SKM though, that when it dies now, the data you entered is rarely lost. And when there's any problem the software, I've found their tech support to be second to none. Case in point - just yesterday, I was finishing up a large system in SKM, when my Arc-Flash wouldn't work. I tried all of the usual fixes, to no avail. SKM was able to log into fastsupport.com, where they could assistively control my keyboard. I watched as he went through several fix attempts, and he finally got it working. Bottom line for me is that they've always been able to solve my problems. And, although they're quick to say they're not giving engineering advice, they're extremely helpful in the understanding of not just the package, but also theory.

And one last point ot make .. we also have EasyPower at work, and there are folks in our office who prefer that. Probably like me, with the same bias due to knowing one package over the other. I think they're both priced outrageously high and similar, so your safe with either package.


John M

 

[dahualin]

We use SKM and have done so for approx 15 years.

David,
The program helps calculate complicated systems that have many panels and sources. AHJ's require it for elevators and life safety emergency systems. Clients require it for reliability and setting of adjustable OCPD's.

When we design electrical system to specify panel board AIC rating, I can easily calculate available short circuit current at each panel board, MCC, and disconnnect switch with spreadsheet. I don't need any software such as SKM.

We normally show generic circuit breaker information on our panel schedules for elevators and life safety system, such as 100AT/125AF without specifying any specific circuit breaker model no from Square D, Siemens, Eaton, or GE. I am wondering how you guys can do selective coordination without those specific circuit breaker's time-current curve. I would assume the electric contractor shall hire other electrical PE to do the selective coordination study after they have decided which manufacturer they want. Am I right? Thanks.

 

[jaraujo1]

I faced similar decision 10 months ago

I faced similar decision 10 months ago

The firm I work for have SKM but the license had expired,
I start reviewing and found rather difficult to learn the program. I looked into renewing the license but it was rather expensive. I also looked into what is the best approach, renew it or get another software package.

First I tried to understand why is SKM so clumsy, I either read of someone told me that SKM was developed way back when there was no window programming and the program core is not window based. Later they tried to switch over to window but the native program core remain in the original language (do not quote me because I do not have the facts).

I researched what was there of the most recent development using window based core programming. I settled for ETAP, I have been happy so far.
I can do load flow, device coordination, short circuit analysis and arc flash analysis. They have modules where you could run cable calculation, system design and other very useful engineering tasks (www.etap.com)

One problem that is true for any analysis program, the library revision. I am running all the calculation stated in the previous paragraph for a large industrial project with 3 substations with Korean gears. those gears are not in their standard libraries. They have provided me with instructions on how to customize the library to the devices but it is not an easy task and the chances of making errors are a huge responsibility when it comes to ACB, VCB and MCCB.

The technical support is great they will be doing the modeling of the above devices for me.

Just my 3 cents worth of feedback.

 

[weressl]

I am an electrical engineer doing electrical system design for new building projects, renovation projects. And I have never done any short circuit and coordination studies. The only thing I have done may related to this is short circuit current calcuation to calcuate available short circuit from power source at each panel location so that we can design panel schedule with right AIC rating.

I understand the benefit of doing short circuit and coordination study. I am curious about which AHJ requires this kind of studies and what kind of clients require this kind of studies and what code requires this kind of studies. I have heard about OSHA requires Arc Flash study. Thanks.

NEC requires it, OSHA requires it.

SC and protective device coordination studies are the first two elements necessary for an Arc Flash study.

 

[markstg]

I am not attacking anyone here, I am very curious about the "AHJ" aspect of this thread.


First, I know that AHJ and its meaning varies from jurisdiction to jurisdiction.
Second, I will respond with what I experience in NY (which is sometimes just a joke...hence my interest in this aspect of the thread)

I am going to reiterate I am not picking on, or intending malice towards anyone, especially the guys here.


I completely understand the value of the Studies being required and performed. I also understand that the results may not always be the same, it depends on who is doing them, with what program, based on different methods.

So, for the engineers on this thread, when you mention the studies are performed for the AHJs, who do you really mean?

Where my interest comes in. I am an inspector. If you were to present me with the results of your study, most likely I would pass it on to the building department and put a copy in the job folder.
I can tell you I would not be comfortable in judging whether or not the results of the study were/are accurate.
I can also tell you that there is maybe 1 or 2 jurisdictions in the 3 counties (approximately 85 jurisdiction) that have the staff to look at and understand the results of the study.

So who is really looking at the results of your studies?
Is it really a 'chip' the building departments put away for the future, if something should go wrong with the engineering of that particular job?

Pierre....I don't think it is up to you to approve, critically review, etc the short circuit study, or the OCPD study that is done the Electrical Engineering Firm. Such studies must be stamped by the Professional Engineer who is in responsible charge of the electrical equipment design. The PE Stamp is what I would be looking for.

 

[drbond24]

I've used SKM in the past and agree with the assessment of the others here.

I now use EasyPower and it is easier to figure out and use (in my opinion).

 

[ron]

Markstg,
Just as a note, I've done countless short circuit, overcurrent PD coordination and arc flash studies and have not been asked to sign/stamp/seal any of them. Although it would be easy enough to do so, but I've never been asked.

 

[Pierre C Belarge]

Pierre....I don't think it is up to you to approve, critically review, etc the short circuit study, or the OCPD study that is done the Electrical Engineering Firm. Such studies must be stamped by the Professional Engineer who is in responsible charge of the electrical equipment design. The PE Stamp is what I would be looking for.

I would not approve it, as I mentioned, I would pass it on.
I was just curious as to who is actually looking at the studies? Is there ever a challenge to the study as being improperly performed?

 

[Pierre C Belarge]

Sometimes I will run into and installation that I am unsure of if it is suitable. Then I will request the letter from an engineer...passing the responsibility of my approval directly on to the engineer.