How do I measure kW with the WattNode?
The WattNode is designed to measure watt-hours or kilowatt-hours. In order to measure kW, you will need to divide out the time interval (in hours) when calculating the slope for the WattNode. The time interval that you need to divide out will be the sample interval being used during the monitoring process. For example, a three-phase, four-wire, 277/480V WattNode (WNA-3Y-480-P) is being used with three 200A CT’s, and is collecting data at a sample rate of 5 minutes. In order to determine the slope for monitoring kW, we first determine the slope for monitoring kWh, which would be (0.05771) * (200) = 11.542 Watt-hours per pulse, or (11.542)/1000 = 0.011542 kWh/pulse. Now, since our sample interval is 5 minutes, we need to divide our slope by this time interval in units of hours. Thus, we divide 0.011542kWh by 5min/60min or 0.0833hours, and get 0.011542kWh/0.0833h = 0.1386kW. Our slope would be 0.1386 and our units would be kW.
