Questions for a new installation

General questions and discussions focused around the EKM Metering System. Discuss your meters, installations, and meter communications here.
Jameson
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Re: Questions for a new installation

Post by Jameson » Tue Nov 17, 2015 9:39 am

First, is it possible to use two current transformers on a single input of an omnimeter to read the total of the two lines?
Yes, you can run parallel wires from the same phase either through a single CT or you can run them through 2 CTs connected to the same inputs on the Omnimeter. Make sure that if you have say a 400 amp system that you use 2 400 amp CTs with your meter set to a 400 amp CT ratio. Ideally I would solder the CT wires together and then connect them to the meter.
Next, can I use one omnimeter to monitor three lines on the same phase? or are the three inputs strictly for three phase power? If so, could I monitor three separate 220v 2 wire single phase sources?
You will not have an accurate Total kWh if you do this. If you use the Omnimeter Pulse v.4, you will get accurate kWh on Each Line. With this you can have kWh and watts for each of the three 2 wire systems.
and last, for an installation with no internet, If I were to write a program to log data on my Raspberry Pi, Is the database format available for your dash software?
We use sqlite databases. I would not know how to tell you the format of the database itself, but if you want to take a look, you can make a copy of your Dash DB then open it up and see what is in there. To find the DB on a Mac I hold the "option key" when opening the EKM Dash.
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371

Zaaphod
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Re: Questions for a new installation

Post by Zaaphod » Tue Nov 17, 2015 3:48 pm

You will not have an accurate Total kWh if you do this. If you use the Omnimeter Pulse v.4, you will get accurate kWh on Each Line. With this you can have kWh and watts for each of the three 2 wire systems.
So with Omnimeter pluse V.4, everything would be accurate except the total KWh? I would be looking at each individually. Am I correct that this would only work for 2 wire systems and if any of them were 3 or more wire it would need it's own meter?

I have one more question...
Is there the capability to mathematically calculate the energy usage? Here are two scenarios -
say I have a feed thru panel. I have one omni meter reading the incoming total power on the main, another one reading the total power going out the feed thru, could I calculate by subtraction what the breakers on the panel would be using?
or
say I have a three phase panel with 3 branch circuits, each it's own omnimeter, can I mathamatically add the usage of the three meters to get total power for the panel?

Jameson
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Re: Questions for a new installation

Post by Jameson » Tue Nov 17, 2015 3:55 pm

So with Omnimeter pluse V.4, everything would be accurate except the total KWh? I would be looking at each individually. Am I correct that this would only work for 2 wire systems and if any of them were 3 or more wire it would need it's own meter?
Yes, Total kWh is no longer necessarily accurate when you use the Omnimeter Pulse v.4 as 3 separate kWh Meters. Yes, if you were to do this on a 3-wire system I would use a separate Omnimeter for each 3-wire system.
Is there the capability to mathematically calculate the energy usage? Here are two scenarios -
I would say yes absolutely, but I may not understand your question.

If you meter 100 kWH into the panel and meter 60 kWh going to one circuit, you can infer that 40 kWh are going to the other circuit. Best would be to have 1 meter on each circuit and infer the total, but that is up to you.
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371

Zaaphod
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Joined: Fri Oct 23, 2015 2:04 pm

Re: Questions for a new installation

Post by Zaaphod » Tue Nov 17, 2015 6:06 pm

Great, thanks for this information. It will be helpful when planning exactly where to physically place meters and which circuits will be monitored

Zaaphod
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Joined: Fri Oct 23, 2015 2:04 pm

Re: Questions for a new installation

Post by Zaaphod » Sat Dec 05, 2015 1:36 pm

Is there a way to configure where the dash meter read database is stored? I'm trying to run dash on a windows 10 tablet.. storage is extremely limited, so I don't want the database on the tablet, I want in a specific directory on my NAS box. I can't find an option for the location of the database.

Jameson
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Re: Questions for a new installation

Post by Jameson » Mon Dec 07, 2015 11:01 am

You cannot tell the Dash where to put the database. It needs to be in a known location for the Dash to work properly.

Here is the location of your Dash DB:

Windows 8, 7 and Vista: C:\Users\USER\AppData\Roaming\EKM Dash
Windows XP: C:\Documents and Settings\User\Application Data\EKM Dash
Mac OS X: User/Library/Application Support/EKM Dash/EKM Metering Database.db

I would imagine that your tablet could use an ARM based chip. In which case it wont be able to run the EKM Dash. At this point Dash is restricted to Intel x86 chip architectures.

You could have a dropbox folder (or Bittorrent Sync) folder on your device that is gathering data and another on your NAS device. Setup your Dash to send file based reports to this folder from time to time. This is a good way to offload data and have it on multiple devices.
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371

Zaaphod
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Joined: Fri Oct 23, 2015 2:04 pm

Re: Questions for a new installation

Post by Zaaphod » Mon Dec 07, 2015 12:19 pm

I agree the database needs to be in a know location... but users should be able to specify what that location actually is... and.. having the database where it currently is, is not really the best place for it... because it's tied to the logged in User... so If I'm logged in I see tons of logged data.. but my wife logs in and she sees nothing?? that just isn't the best way to set it up... we would want to both see the same database.

My tablet is windows 10 with an Intel Atom processor, Dash runs fine on it.

The problem isn't getting the database off the tablet, the problem is that tablet can't hold the database at ALL, it just doesn't have enough storage capacity on drive D. I can put an SD card in it, but then I have the same problem... I can't tell it to put the database on D:\

I really don't want a power hungry computer storing this data, so the windows 10 tablet would be ideal, as it only uses a few watts when the screen is off.

I guess I could force it to work and make a symbolic link to the specified path, since the C:\ drive on the tablet uses NTFS.. I would have to go with the memory card also formatted NTFS though as my server hard drives are ZFS and I don't think symbolic links work unless all drives involved are NTFS.

nielo
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RS485 Terminating/Bias Resistors

Post by nielo » Tue May 21, 2019 6:34 pm

Do the v4 and v3 meters have terminating/bias resistors on their RS485 terminals?

Jameson
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Re: Questions for a new installation

Post by Jameson » Wed May 22, 2019 10:01 am

Our Omnimeters do have biasing resistors, they do not have terminating resistors. Our communication hardware solutions (USB Converter, EKM Push, iSerial, 485Bee) are all tuned to work with our EKM Omnimeters. You should not have to use terminating, or biasing resistors with your Omnimeter installation if you use our communication hardware.
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371

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