support/articles/3 Phase KWH Calculation Using a Compound Line Equation
Technical Document PROVEN DATA LOGGING SOLUTION S
3 Phase kWh Calculation Using a Compound Line Equation We can calculate kWh from the readings we take from a SmartReader 3 or a SmartReader Plus 3 data logger. We use a Compound Line Equation to accomplish this. What we are doing is simply applying an external formula to the data we have collected and displaying this on the graph as well.. Using TrendReader 2, the formula looks like the following: Answer1=Answer1+(Source0*Source1+Source2*Source3+Source4*Source5)/1000* Source6*1.7320508*(logger.SampleRate/3600) Answer0=Answer1 Answer1 is the result obtained from performing the calculation. Source0 is AC current 1 Source1 is AC voltage 1 Source2 is AC current 2 Source3 is AC voltage 2 Source4 is AC current 3 Source5 is AC voltage 3 Source6 is Power Factor (use a value of 1 if this is unknown) Logger.SampleRate is the sample rate of the logger in seconds. Answer0 is the final result that gets plotted to the graph. The equation is basically taking the product of current and voltage for each of the phases and summing them. (Watts) Then it divides by 1000 (kW), multiplies it by the root of 3, the Power Factor, and the sample rate in hours to yield kWh. (Note: The sample rate is always reported in seconds in TrendReader 2 and so to yield hours, this number must be divided by 3600.) The total is added to the previous total and so the graph accumulates kWh usage. You can find the kWh total at any point in time along the graph. The equation as written above will accept voltage and current inputs. If voltage was not actually measured, but was assumed, change Source1, Source3 and Source5 to the assumed voltage when writing the equation or enter the numbers manually when applying the graph (more below on this).
In TrendReader 2, select Compound Line from the Equation menu and take the steps on the following pages:
Technical Document PROVEN DATA LOGGING SOLUTION S
Technical Document PROVEN DATA LOGGING SOLUTION S
Enter the equation as written in the blank form.
Technical Document PROVEN DATA LOGGING SOLUTION S
Technical Document PROVEN DATA LOGGING SOLUTION S
The next step is to add the kWh calculation to the graph. This is accomplished by displaying the graph and selecting Compount Line from the Graph pull down menu.
Select the equation from the list.
Technical Document PROVEN DATA LOGGING SOLUTION S You now click on each Source variable and assign it to the channel of data that you want to process. Enter the Power Factor value in Source6. Click OK when done.
The kWh line is in red and the kWh axis appears on the graph.
The data table shows the kWh used at each sample interval. Toll-Free 1.800.663.7845 Phone 1.604.591.1128 [email protected]
www.acrsystems.com ISO9001:2000 Certified
Document No. 00-0000 Release Date 20/08/08 Revision -
3 Phase kWh Calculation Using a Compound Line Equation We can calculate kWh from the readings we take from a SmartReader 3 or a SmartReader Plus 3 data logger. We use a Compound Line Equation to accomplish this. What we are doing is simply applying an external formula to the data we have collected and displaying this on the graph as well.. Using TrendReader 2, the formula looks like the following: Answer1=Answer1+(Source0*Source1+Source2*Source3+Source4*Source5)/1000* Source6*1.7320508*(logger.SampleRate/3600) Answer0=Answer1 Answer1 is the result obtained from performing the calculation. Source0 is AC current 1 Source1 is AC voltage 1 Source2 is AC current 2 Source3 is AC voltage 2 Source4 is AC current 3 Source5 is AC voltage 3 Source6 is Power Factor (use a value of 1 if this is unknown) Logger.SampleRate is the sample rate of the logger in seconds. Answer0 is the final result that gets plotted to the graph. The equation is basically taking the product of current and voltage for each of the phases and summing them. (Watts) Then it divides by 1000 (kW), multiplies it by the root of 3, the Power Factor, and the sample rate in hours to yield kWh. (Note: The sample rate is always reported in seconds in TrendReader 2 and so to yield hours, this number must be divided by 3600.) The total is added to the previous total and so the graph accumulates kWh usage. You can find the kWh total at any point in time along the graph. The equation as written above will accept voltage and current inputs. If voltage was not actually measured, but was assumed, change Source1, Source3 and Source5 to the assumed voltage when writing the equation or enter the numbers manually when applying the graph (more below on this).
In TrendReader 2, select Compound Line from the Equation menu and take the steps on the following pages:
Technical Document PROVEN DATA LOGGING SOLUTION S
Technical Document PROVEN DATA LOGGING SOLUTION S
Enter the equation as written in the blank form.
Technical Document PROVEN DATA LOGGING SOLUTION S
Technical Document PROVEN DATA LOGGING SOLUTION S
The next step is to add the kWh calculation to the graph. This is accomplished by displaying the graph and selecting Compount Line from the Graph pull down menu.
Select the equation from the list.
Technical Document PROVEN DATA LOGGING SOLUTION S You now click on each Source variable and assign it to the channel of data that you want to process. Enter the Power Factor value in Source6. Click OK when done.
The kWh line is in red and the kWh axis appears on the graph.
The data table shows the kWh used at each sample interval. Toll-Free 1.800.663.7845 Phone 1.604.591.1128 [email protected]
www.acrsystems.com ISO9001:2000 Certified
Document No. 00-0000 Release Date 20/08/08 Revision -
