Brultech Setup Question - Micro 80 CTs on Channel 2

[Scott12v]

I am a current TED user transitioning to multiple Brultech ECM-1240s for more granular monitoring.

I started with my subpanel since it is easier to get to and install everything. The sub-panel is 100AMP being fed from a 200AMP main panel. I am monitoring the sub-panel using Micro 100 CTs on Channel 1.

On Channel 2, I am monitoring a 60AMP breaker that goes out to a hot tub (through a SPA disconnect box mounted outside). I am monitoring this circuit with a pair of Micro 80 CTs on Channel 2. The CTs are hooked up as in this picture from Brultech's site:

I also have the two CTs facing in opposite directions per what I believe the manual is telling me (I couldn't find a copy online).

With the SPA going full blast (two pumps and a heater), the readings I am getting with the Brultech don't make sense. On the 60 AMP circuit, I am getting a reading of 90 AMPs. Obviously this doesn't seem right. I would have expected it to be right around 50 AMPs based on the spa manual.
Here is what the realtime monitor looks like with everything on ths spa turned on:

I used the CT Calculator tool to get what I believe are the correct settings:

I have both white wires from the CT going to the "DUAL terminal and both black wires going to the COM terminal with a 7.87 ohm resistor in between.


Here are the settings entered in the Brultech Software:

Does anybody have any ideas on what I am doing wrong? Or do I just not understand the results that I am seeing.

The other channels "seem" to be okay based on turning lights on and off (with known wattages), but I given the results I'm seeing with the SPA, I'm not sure I can trust any of the channels.

Thanks,
Scott

 

[rbroders]

The results look correct to me. The total current is 89.8A across both 110V phases. The "220V" current is half that ~45A. I think the key is to make sure the numbers go up when you turn things on and down when you turn things off.

--Bob

 

[personalt]

The results look correct to me. The total current is 89.8A across both 110V phases. The "220V" current is half that ~45A. I think the key is to make sure the numbers go up when you turn things on and down when you turn things off.

--Bob

I would think that the watts would need to be doubled but not sure about the amps unless the brultech is making adjustments to account for the fact that it is displaying 120 volt circuits next to 240 volt circuits. Check out the watts and see how they compare to the amps. If I recall the watts its power (amps) multiplied by volts. If the 90 amps multiplied by ~120 is the watts that its my guess.

 

[Btech]

I am a current TED user transitioning to multiple Brultech ECM-1240s for more granular monitoring.

I started with my subpanel since it is easier to get to and install everything. The sub-panel is 100AMP being fed from a 200AMP main panel. I am monitoring the sub-panel using Micro 100 CTs on Channel 1.

On Channel 2, I am monitoring a 60AMP breaker that goes out to a hot tub (through a SPA disconnect box mounted outside). I am monitoring this circuit with a pair of Micro 80 CTs on Channel 2. The CTs are hooked up as in this picture from Brultech's site:

I also have the two CTs facing in opposite directions per what I believe the manual is telling me (I couldn't find a copy online).

With the SPA going full blast (two pumps and a heater), the readings I am getting with the Brultech don't make sense. On the 60 AMP circuit, I am getting a reading of 90 AMPs. Obviously this doesn't seem right. I would have expected it to be right around 50 AMPs based on the spa manual.
Here is what the realtime monitor looks like with everything on ths spa turned on:

I used the CT Calculator tool to get what I believe are the correct settings:

I have both white wires from the CT going to the "DUAL terminal and both black wires going to the COM terminal with a 7.87 ohm resistor in between.


Here are the settings entered in the Brultech Software:

Does anybody have any ideas on what I am doing wrong? Or do I just not understand the results that I am seeing.

The other channels "seem" to be okay based on turning lights on and off (with known wattages), but I given the results I'm seeing with the SPA, I'm not sure I can trust any of the channels.

Thanks,
Scott

Scott,

Your readings seem correct. The reason that the displayed current is so high is that it is summing both CT currents and using the 120V reference voltage to calculate true power. The actual line current would be 1/2 of the displayed value (assuming a balanced load).

Paul

 

[Ira]

It looks correct to me. My 240V electric oven, when on, shows about 29 amps at almost 3600 watts. In reality, it's about 14.5 amps and almost 1800 watts across each conductor, i.e., "circuit".

I have several channels that "monitor" multiple 120V circuits...two or more CT's on different hot wires all connected to the same channel. It shows up in the real time display as the sum of the power on those circuits.

To verify your results...connect one of the spa CT's to one aux channel and the other CT to a different aux channel, and adjust any configuration numbers if needed. The sum of the numbers for those two channels should equal what you now see on CH2. You should see about 5400 watts on each of the aux channels when the spa is on.

 

[Scott12v]

It looks correct to me. My 240V electric oven, when on, shows about 29 amps at almost 3600 watts. In reality, it's about 14.5 amps and almost 1800 watts across each conductor, i.e., "circuit".

I have several channels that "monitor" multiple 120V circuits...two or more CT's on different hot wires all connected to the same channel. It shows up in the real time display as the sum of the power on those circuits.

To verify your results...connect one of the spa CT's to one aux channel and the other CT to a different aux channel, and adjust any configuration numbers if needed. The sum of the numbers for those two channels should equal what you now see on CH2. You should see about 5400 watts on each of the aux channels when the spa is on.

Thanks for the replys everyone. I did get a very similar response from Paul at Brultech:

Your readings seem correct. The reason that the displayed current is

so high is that it is summing both CT currents and using the 120V

reference voltage to calculate true power. The actual line current

would be 1/2 of the displayed value (assuming a balanced load).


I do have a question about the Watts that I am using. If I understand correctly, the AMPs are doubled, but the wattage is correct?
Using Amps = Watts/Volts I would get 10881 Watts / 240 Volts = 45.3 AMPs

So in other words, if I am trying to understand how much power I am actually using, I am using 10,881 Watts...is that correct?

Ira - thanks for the tip about testing this on one of the Aux channels. That should work.

Thanks,
Scott

 

[Ira]

The amps aren't really doubled. It's really the sum of the amps seen by each of the two CT's. It just so happens that the CT's are each on "half" of a 240V circuit. The only way it will turn out that the amps are double what either one of the CT's see is if the load is balanced. For example, I think some electric clothes dryers use 240V for the heating elements, but 120V for the motor. In that case, the load would never be balanced and the amps never be double what one of the CT's see. When the dryer is running and the heating elements are drawing power, one CT would see half the heater load, while the other CT would see the other half of the heater load plus the 120V motor load. When the heating element is off but the dryer is spinning (e.g., "air dry" or the elements have hit the temp limit), you might see nothing on one CT and the 120V motor on the other.

Think about what you would see if you moved the CT's to separate aux channels. The total (unfortunately only watts if using AUX channels) should equal to what you see on CH2.

In fact, if your SPA circuit is powering a 240V heater and a 120V motor, you have an unbalanced load.

Of course, I could be wrong about all of the above.


Paul...why does the ECM real time display only show amps for CH1 and CH2?