Occasionally, incorrect CT ratings may be registered in the Onboarding application. For instance, an installed 120A CT that has a 1200:1 turn ratio is registered as 200A CT that has a 2000:1 turn ratio.
Valid measurements can be calculated for historic data except if the CT installed was too small to support the actual circuit current. For instance, 120A CT is installed on a line that can deliver up to 400A.
When changing the CT ratio in the Onboarding application, historical data is not changed and the Wattwatchers support team does not update historical data. You will need to externally adjust the data from the date the error occurred until the time this is corrected in the device configuration.
Use the following table to scale the data for power, energy and current measurements over the period required.
For example, if the rating of the CTs actually installed is 200A and the incorrect rating configured during installation was 60A (the default setting in Onboarding) then the data needs to be scaled by a factor of 2.666666667 (or 2000/750).
This method is not applicable for Rogowski Coil devices as the coil ratio is fixed and normal Auditor CTs are not compatible with the Rogowski Coil devices.
Voltage and frequency readings are not impacted by incorrect CT ratios and do not need to be scaled.