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Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 7:35 am
by vespaman
Looking at adding another GEM, since all channels are used up on my old (2013) GEM.
Now, it looks like there are two versions of GEM, where one is specified to work with three phases, whereas the residential is not.
I guess this means that I need the commercial version? Sounds expensive.
(Where I am at, all houses uses 230V 3 phases, only apartments has single phases)
Did I understand this correctly, and if so, what would be the price for a commercial GEM with ethernet interface?
Thanks,
Micael
Re: Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 8:34 am
by Teken
Hello Micael,
The only difference between the commercial vs residential is the use of a 3 phase harness kit as far as I am aware. Send in a request to the sales department to confirm the costs.
Re: Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 8:43 am
by vespaman
What is that (the three phase harness kit)?
I don't have this on my old GEM, I just have normal CT's and program which phase they reside on...
Re: Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 8:56 am
by Teken
Going off memory it was a modified PT (Potential Transformer) that had the ability to monitor all three legs of the electrical phases. If your GEM is set up to monitor three phase what does the PT look like and how is it hooked up to monitor all three phases?
Re: Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 9:03 am
by vespaman
It is a single PT off one phase. Apparently there's some magic going on to resolve the voltage on the other two phases from this and the current run through the other phases. (All from Ben, I never understood how it actually worked).
Re: Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 9:13 am
by Teken
vespaman wrote:It is a single PT off one phase. Apparently there's some magic going on to resolve the voltage on the other two phases from this and the current run through the other phases. (All from Ben, I never understood how it actually worked).
Hrmm, that's interesting as this is like the 240 VAC doubling feature they use for balanced 240 VAC loads to save on CT's. I would have to gather if the system has operated fine using software to operate in 3 phase mode.
You need only purchase the exact same GEM hardware and forgo the extra expense.
In the past when 3 phase was discussed the special harness was noted by Ben. I have to gather it looks like the one I received but for 120 / 240 use. I would assume it would be spec'd for 120 / 208 for North America light commercial and 277 / 480 for high voltage commercial applications.
Re: Commercial vs Residential GEM?
Posted: Sat Apr 22, 2017 9:56 am
by vespaman
Maybe Ben can chime in, it would be useful to know. I don't think there was a specific 3 phase version in 2013? But maybe I have forgotten, it was some years ago...
Or maybe it has to do with what kind of three phase system (we have TN over here, 400V between the phases).
Re: Commercial vs Residential GEM?
Posted: Mon Apr 24, 2017 9:21 am
by ben
vespaman wrote:Maybe Ben can chime in, it would be useful to know. I don't think there was a specific 3 phase version in 2013? But maybe I have forgotten, it was some years ago...
Or maybe it has to do with what kind of three phase system (we have TN over here, 400V between the phases).
In 2013 there wasn't a specific 3-phase version, correct. 3-phase now requires a package that comes along with the GEM including a special high-accuracy PT.
We still only support 3-phase Wye still.
Send an email to Tammy with what you're looking for (sales(at)brultech.com) and she'll get you a quote together.
Re: Commercial vs Residential GEM?
Posted: Sat Jul 22, 2017 12:49 am
by vespaman
ben wrote:vespaman wrote:Maybe Ben can chime in, it would be useful to know. I don't think there was a specific 3 phase version in 2013? But maybe I have forgotten, it was some years ago...
Or maybe it has to do with what kind of three phase system (we have TN over here, 400V between the phases).
In 2013 there wasn't a specific 3-phase version, correct. 3-phase now requires a package that comes along with the GEM including a special high-accuracy PT.
We still only support 3-phase Wye still.
Send an email to Tammy with what you're looking for (sales(at)brultech.com) and she'll get you a quote together.
So, does this mean that the new 3phase kit gives better accuracy, and if so, is the kit available as a retrofit/upgrade to us older 3-phase users?
Or is there some way of using this new kit for both GEM's (that would be the best of course, since space is getting sparse) ?
And finally, reading on the product page, it says
Code: Select all
Supports 120V/208V four wire wye (Y) systems
but does it, in reality, also support 230/400V four wire Y aswell?
Re: Commercial vs Residential GEM?
Posted: Mon Jul 24, 2017 10:21 am
by ben
vespaman wrote:ben wrote:vespaman wrote:Maybe Ben can chime in, it would be useful to know. I don't think there was a specific 3 phase version in 2013? But maybe I have forgotten, it was some years ago...
Or maybe it has to do with what kind of three phase system (we have TN over here, 400V between the phases).
In 2013 there wasn't a specific 3-phase version, correct. 3-phase now requires a package that comes along with the GEM including a special high-accuracy PT.
We still only support 3-phase Wye still.
Send an email to Tammy with what you're looking for (sales(at)brultech.com) and she'll get you a quote together.
So, does this mean that the new 3phase kit gives better accuracy, and if so, is the kit available as a retrofit/upgrade to us older 3-phase users?
Or is there some way of using this new kit for both GEM's (that would be the best of course, since space is getting sparse) ?
And finally, reading on the product page, it says
Code: Select all
Supports 120V/208V four wire wye (Y) systems
but does it, in reality, also support 230/400V four wire Y aswell?
Yeah, the PT in the 3-phase kit is higher accuracy. The old GEMs don't need to be retrofitted if they're working fine.
Yeah, you just need to make sure all the CTs you order are the "-i" versions as they have leads good up to 600V.
Send me an email (ben(at)brultech.com), we can probably work something out given you're a repeat customer.