1. By- EMBUILT TECHNOLOGIES www.embuilt.com energylogger.blogspot.com embuilt.tech@gmail.com

2. Simple Math's Calculation We all know- 1 is 1% of 100 10 is 10% of 100 If two percentage are 10% and 10% then total % is 20%

3. For THD Measurement 1 may be 10% for 100 10 may be 40% for 100 The Total of two percentage as 10% and 10% may be 0.

4. THD Measurement If Voltage (rms) is 100 Volts and first harmonics Voltage is 99 than THD = 14.10% Means for difference of 1 Volt, THD = 14.10% If Voltage (rms) is 100 Volts and first harmonics Voltage is 90 than THD = 43.58% Means for difference of 10Volt, THD = 43.58% Refer Appendix -

5. Example for Sine Wave We all know for pure sine wave THD is 0% If we connect a ideal load with ideal half wave rectifier for positive half. Let the THD of this wave is 37% If we connect a ideal load with ideal half wave rectifier for Negative half. The THD of this wave is also 37%

6. If we add both Rectified waves THD will be zero where as individual wave has THD 37%.

7. Appendix Vrms 2 = (V1 2 +V2 2 +V3 2 +…..+Vn 2 ) THD(%) = (√(V2 2 +V3 2 +…..+Vn 2 )/ √(V1 2 +V2 2 +V3 2 +…..+Vn 2) THD(%)= (√(Vrms 2 -V1 2 )/ Vrms )*100 THD ( dB) or Distortion attenuation a =20*log((THD%)/100)

8. THD Calculation Sheet