Paralleling CTs
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Cogilvie58
- Posts: 3
- Joined: Sun Feb 03, 2013 1:47 pm
Paralleling CTs
I recently installed an EKM meter on a 208 volt (2 hots one neutral) and had to use two CTs for each side of the panel as I could not reroute all of the lines to one side of the panel. Basically L1 has two CTs and L2 has two CTs. Both were wired in parallel and I made sure all of the lines going through each CT were going the correct direction and from the correct phase. After one week the reading (kwh) seems really high (2 X what it should be) so I am wondering if the parallel CTs requires. 0.5 X multiplier so something along these lines or should I have series the CTs. Anyone have any advice on this one?
Re: Paralleling CTs
Yes, you should be fine if you have 2 CTs on line 1 and 2 CTs on line 2. Make sure that you have them wired to the meter in parallel (not in series).
This is used if you have multiple wires which will not fit through one CT that you want to meter. You are correct that all line1 wires must be from Line1 and must pass in the same direction through the CTs. Any given wire should not pass through both the CT A and CT B. If you are using 200 amp CTs, the amperage of each line (CT A + CT B) should not exceed 200 amps.
These CT connection instructions assume an EKM Omnimeter on a 3-wire (2 hots and a Neutral) system:
First mark your 4 CTs: CT A Line 1, CT B Line 1, CT A Line 2, and CT B Line 2
The black wires from CT A Line 1 and CT B Line 1 should go to port 1 on the Omnimeter
The white wires from CT A Line 1 and CT B Line 1 should go to port 2 on the Omnimeter
The black wires from CT A Line 2 and CT B Line 2 should go to port 3 on the Omnimeter
The white wires from CT A Line 2 and CT B Line 2 should go to port 4 on the Omnimeter
If you have any questions, please let us know.
This is used if you have multiple wires which will not fit through one CT that you want to meter. You are correct that all line1 wires must be from Line1 and must pass in the same direction through the CTs. Any given wire should not pass through both the CT A and CT B. If you are using 200 amp CTs, the amperage of each line (CT A + CT B) should not exceed 200 amps.
These CT connection instructions assume an EKM Omnimeter on a 3-wire (2 hots and a Neutral) system:
First mark your 4 CTs: CT A Line 1, CT B Line 1, CT A Line 2, and CT B Line 2
The black wires from CT A Line 1 and CT B Line 1 should go to port 1 on the Omnimeter
The white wires from CT A Line 1 and CT B Line 1 should go to port 2 on the Omnimeter
The black wires from CT A Line 2 and CT B Line 2 should go to port 3 on the Omnimeter
The white wires from CT A Line 2 and CT B Line 2 should go to port 4 on the Omnimeter
If you have any questions, please let us know.
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Cogilvie58
- Posts: 3
- Joined: Sun Feb 03, 2013 1:47 pm
Re: Paralleling CTs
Thanks for your response. I rechecked my wiring and found that I had wired L1 voltage with L2 CTs and visa versa. I corrected this, checked it a few days later which raised another question I forget to ask earlier. Prior to correcting the wiring I had kWh readings of the same magnitude on L1 (544 kwh) and L2(544 kwh). L3 read 0. After correcting the wiring only L1 had changed when I returned so readings were L1 (814) L2 (544) and L3 (0). Is this now correct? or should the kwh be registering on L2 as well? I have never had a meter that showed kwh on more than one screen before so I am a bit confused. Thanks for your help and time.
Re: Paralleling CTs
Hello Cogilvie58,
Glad you got the wiring sorted out.
Please verify that you have an Omnimeter Pulse v.4. (rather than a v.3 Omnimeter) This is the only meter we carry that has the ability to keep track of kilowatt hours on each line separately.
You can see all of the values the Omnimeter Pulse v.4 returns on the screen in Fig 6 here: http://documents.ekmmetering.com/EKM-Om ... -Sheet.pdf
Total kWh (in 4 time of use periods, TOU)
Reverse kWh (in 4 time of use periods, TOU)
Total kWh on Line 1 (value 32 from Fig. 6)
Total kWh on Line 2 (value 34 from Fig. 6)
Total kWh on Line 3 (value 36 from Fig. 6)
And just as an aside, you can configure this meter (using the EKM Dash software) to only display the values you want to see. If you are only interested in Total Watts and Pulse Counts for example, you can just show these values.
Thanks,
Glad you got the wiring sorted out.
Please verify that you have an Omnimeter Pulse v.4. (rather than a v.3 Omnimeter) This is the only meter we carry that has the ability to keep track of kilowatt hours on each line separately.
You can see all of the values the Omnimeter Pulse v.4 returns on the screen in Fig 6 here: http://documents.ekmmetering.com/EKM-Om ... -Sheet.pdf
Total kWh (in 4 time of use periods, TOU)
Reverse kWh (in 4 time of use periods, TOU)
Total kWh on Line 1 (value 32 from Fig. 6)
Total kWh on Line 2 (value 34 from Fig. 6)
Total kWh on Line 3 (value 36 from Fig. 6)
And just as an aside, you can configure this meter (using the EKM Dash software) to only display the values you want to see. If you are only interested in Total Watts and Pulse Counts for example, you can just show these values.
Thanks,
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Cogilvie58
- Posts: 3
- Joined: Sun Feb 03, 2013 1:47 pm
Re: Paralleling CTs
I checked and I have the V3 meter so I am still concerned about the fact that L2 power is not moving at all and L1 power is moving along. I don't think there is a total power screen showing. Please advise.
Re: Paralleling CTs
Hello Cogilvie,
If you have a v.3 meter, this meter does not provide kWh on Line 1 and a separate kWh on Line 2.
I imagine you are looking at a different data field. Possibly you are looking at Register 1 which is for "Total kWh" and Register 2 which is "Reverse kWh". If you are not sending energy to the grid with a grid tied system Register 2 should not increment. So it sounds like this is what you are seeing - which is GOOD!
Here is a page that explains what all of the values are that display on the LCD screen of your meter: http://documents.ekmmetering.com/EKM_Me ... eading.pdf
If you have any questions, please let us know.
Thanks,
If you have a v.3 meter, this meter does not provide kWh on Line 1 and a separate kWh on Line 2.
I imagine you are looking at a different data field. Possibly you are looking at Register 1 which is for "Total kWh" and Register 2 which is "Reverse kWh". If you are not sending energy to the grid with a grid tied system Register 2 should not increment. So it sounds like this is what you are seeing - which is GOOD!
Here is a page that explains what all of the values are that display on the LCD screen of your meter: http://documents.ekmmetering.com/EKM_Me ... eading.pdf
If you have any questions, please let us know.
Thanks,