[Equest-users] [eQuest-users] Transformers in Energy Model
Sami, Vikram
Vikram.Sami at perkinswill.com
Wed Aug 18 14:32:43 PDT 2010
This<http://www.youtube.com/watch?v=0Xk624DY1-0&feature=related> might help....
Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462 f: 404.892.5823 e: vikram.sami at perkinswill.com www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will. Ideas + buildings that honor the broader goals of society
From: Nick Caton [mailto:ncaton at smithboucher.com]
Sent: Wednesday, August 18, 2010 5:29 PM
To: Nick Caton; Sami, Vikram; Jason Boehning; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] [eQuest-users] Transformers in Energy Model
Hi everyone,
My head is still spinning from the posting a few days back regarding transformer losses... I'm about ready to conclude this is one of those "not really fully implemented" features, but I hope I'm missing something...
Simple question:
* You're modeling a 300kVA transformer which loses 7,500W at full load conditions. Put another way, its efficiency at 100% loading is 97.5%.
* TRANSFORMER-SIZE = 300
* TRANSFORMER-LOSS = ?
My reading and re-reading of the DOE2 documentation (copied below) has led me to believe TRANSFORMER-LOSS = 7.5kW/300kW = .025, or 2.5%.
If you simulate an hour with a 300kW (100% part load) draw, the calculated transformer loss would be, by my understanding:
(TRANSFORMER-SIZE) x (TRANSFORMER-LOSS) x (TRANS-LOSS-FPLR value) = 300kW x .025 x 1.00 = 7.5kW
This interpretation is consistent with the following default/range info for TRANSFORMER-LOSS:
[cid:image001.png at 01CB3EFB.5AE08C90]
As eQuest appears to simultaneously caution against values >1, but also requires an input between 1.0 and 1.5 (when doing a BUILDING/SUB-METER meter - UTILITY appears unaffected by this behavior), I think either the help files or the program is flat-out wrong. Is TRANSFORMER-LOSS really truly a ratio, as in: (300kW+7.5kW)/300kW = 1.025? This seems incongruous with both the TRANSFORMER-LOSS and TRANS-LOSS-FPLR help entries (copied below). Entering a value >1 like this does pop up a caution as the default/range entry above suggests.
Whatever interpretation of TRANSFORMER-LOSS is corrrect, the eQuest interface needs work, as both the spreadsheet and detailed-window views round any input figures to the nearest integer (0,1,2... etc), preventing one from using a value like either 1.025 or 0.025. I have found entering TRANSFORMER-LOSS values like .025 in the parametric interface does work however. Modeled electric consumptions fluctuated up/down as I anticipated with the interpretation that TRANSFORMER-LOSS should be a number < 1. Entering values manually in the *.inp has given me mixed results - eQuest will sometimes spit out a BDL error upon opening the file and overwrite the value with a zero or remove the line - behavior is sporadic and may be related to experimenting with already-developed models.
I hope someone else has dived into this and can comment as to whether this is truly a useable feature at this point. I think it is functional, but it sure is a headache - the interface behaving this way makes me concerned I'm misunderstanding something...
Here are entries from the help files I'm referencing:
TRANSFORMER-LOSS
The fraction of output power that is lost at the transformer at full load conditions (full load is equal to TRANSFORMER-SIZE).
TRANS-LOSS-FPLR
Takes the U-name of a curve that gives the multiplier on TRANSFORMER-LOSS as a function of the part load ratio (current hour load on the meter divided by TRANSFORMER-SIZE). The transformer loss is calculated hourly as
(TRANSFORMER-SIZE) x (TRANSFORMER-LOSS) x (TRANS-LOSS-FPLR value)
The load is the sum of that due to all directly connected equipment and, for TYPE = UTILITY and BUILDING, other ELEC-METERs. The default curve is linear from 0.1 at zero load to 1.0 at full load.
~Nick
[cid:image002.jpg at 01CB3EFB.5AE08C90]
NICK CATON, E.I.T.
PROJECT ENGINEER
25501 west valley parkway
olathe ks 66061
direct 913 344.0036
fax 913 345.0617
Check out our new web-site @ www.smithboucher.com
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Monday, August 16, 2010 4:54 PM
To: Sami, Vikram; Jason Boehning; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] [eQuest-users] Transformers in Energy Model
First, thanks to Jason for the heads up! Taking credit for premium efficiency transformers is a pretty novel idea in my circles.
I'm re-directing this response/discussion to eQuest-users as I'm applying this in eQuest and have found a snag along the way...
After coming up with and creating a custom TRANS-LOSS-FPLR curve using manufacturer data, I hop over to create a new meter to assign this to. The default transformer size field starts off blank, as transformer losses are not normally modeled. After entering the transformer size (225kVA) on the first screen, I immediately encounter the following dialog:
[cid:image003.png at 01CB3EFB.5AE08C90]
[text includes: "Range Checking Violation: Value must be > 1"]
Hmm. This seems odd... the text files for TRANSFORMER-LOSS and TRANS-LOSS-FPLR both indicate this value should be a fraction of the Transformer size representing the maximum loss (therefore < 1). In my example, the 225kVA transformer has a maximum loss (at full load) of 3,898VA, so I was expecting TRANSFOMER-LOSS should be 3898/225000 = 0.01732. Regardless, I haven't entered anything in that field yet... so clicking Cancel to proceed, I return to the following:
[cid:image004.png at 01CB3EFB.5AE08C90]
Hmm.
The error appears to result from the "Loss:" field being unpopulated. I cannot however input the Loss ratio (clouded "n/a") for the custom curve to be applied against! The field ignores anything I type when highlighted...
Okay so saving and exiting, I navigate the .inp to add TRANSFORMER-LOSS there:
"Step Down Meter" = ELEC-METER
TYPE = BUILDING
TRANSFORMER-SIZE = 225
TRANSFORMER-LOSS = .01732
TRANS-LOSS-FPLR = "Custom Xfrmr fPLR"
..
Starting eQuest back up, the following error is generated in BDL - (eQuest proceeds to open and overwrite .01732 with a zero):
*13249* "Step Down Meter" = ELEC-METER
*13250* TYPE = BUILDING
*13251* TRANSFORMER-SIZE = 225
*13252* TRANSFORMER-LOSS = .01732
*ERROR**************************** ====== ****************************************************
*ERROR*****VALUE NOT BETWEEN 1.0000 AND 1.5000
*13253* TRANS-LOSS-FPLR = "Custom Xfrmr fPLR"
Here's where I throw up my hands! What interpretation of TRANSFORMER-LOSS results in a value that would always fall between 1.0 and 1.5?
On a related note: I've read through all the help files regarding electrical meters (I think)... Once this is meter up and running, can anyone suggest any method for applying a specific subset of electric loads (say, only plug loads) to this new meter with the transformer losses defined?
~Nick
[cid:image002.jpg at 01CB3EFB.5AE08C90]
NICK CATON, E.I.T.
PROJECT ENGINEER
25501 west valley parkway
olathe ks 66061
direct 913 344.0036
fax 913 345.0617
Check out our new web-site @ www.smithboucher.com
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Wednesday, August 11, 2010 4:00 PM
To: Sami, Vikram; Jason Boehning; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Transformers in Energy Model
I should have mentioned I was referring to eQUEST...
Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462 f: 404.892.5823 e: vikram.sami at perkinswill.com www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will. Ideas + buildings that honor the broader goals of society
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Wednesday, August 11, 2010 4:31 PM
To: Jason Boehning; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Transformers in Energy Model
You can model transformer sizes and losses in the detailed edit mode when you open up you electric meter.
I have to confess I have not modeled a transformer in a model yet (the default is not to model a transformer and the loss associated). You can specify a loss part load curve too:
TRANS-LOSS-FPLR
Takes the U-name of a curve that gives the multiplier on TRANSFORMER-LOSS as a function of the part load ratio (current hour load on the meter divided by TRANSFORMER-SIZE). The transformer loss is calculated hourly as
(TRANSFORMER-SIZE) x (TRANSFORMER-LOSS) x (TRANS-LOSS-FPLR value)
The load is the sum of that due to all directly connected equipment and, for TYPE = UTILITY and BUILDING, other ELEC-METERs. The default curve is linear from 0.1 at zero load to 1.0 at full load.
Like I said I haven't done it yet - good luck. Let me know how it turns out
Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462 f: 404.892.5823 e: vikram.sami at perkinswill.com www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will. Ideas + buildings that honor the broader goals of society
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jason Boehning
Sent: Wednesday, August 11, 2010 4:14 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Transformers in Energy Model
I am new to energy modeling and I am curious if there is a way to take credit for more efficient transformers in an energy model. Some of our transformer reps have said that there is not a LEED credit for more efficient transformers, but you have to gain the credit through the energy model. Would it just be through more heat in a space? I appreciate any information I can get in this matter.
Best Regards,
Jason Boehning, EIT
Mechanical Engineer
[cid:image005.gif at 01CB3EFB.5AE08C90]
6161 Savoy, Suite 1212
Houston, Texas 77036
v. 713.482.2322
f. 713.482.2314
e. Jason.Boehning at ricegardner.com<mailto:Jason.Boehning at ricegardner.com>
This email and any files transmitted with it are confidential and intended solely for the addressee. If you are not the named addressee you should not disseminate, distribute, copy, or alter this email.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100818/151a6efb/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 12260 bytes
Desc: image001.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100818/151a6efb/attachment-0003.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 1459 bytes
Desc: image002.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100818/151a6efb/attachment-0001.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.png
Type: image/png
Size: 9972 bytes
Desc: image003.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100818/151a6efb/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image004.png
Type: image/png
Size: 17399 bytes
Desc: image004.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100818/151a6efb/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image005.gif
Type: image/gif
Size: 3662 bytes
Desc: image005.gif
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20100818/151a6efb/attachment-0001.gif>
More information about the Equest-users
mailing list