Sine Wave UPS Testing
Today demand of pure sine wave inverter/UPS is increasing because square wave UPS/Inverter can not run various equipments. So we have taken a sine wave UPS for testing.
We can know the purity of sine wave inverter by harmonics analysis. A square wave inverter has very high voltage THD at output whereas pure sine wave has zero THD (Ideal).
UPS Harmonic Test Report
Date: 11-11-2014
Standard
UL1778 article 49 Harmonic Distortion Test
Instrument Under Test
UPS 600VA
Company Name
Sukm
Rated Voltage and Load
12V, 50A
Battery Type
Tubular Battery
Test Condition
On battery source (Assuming full charge battery)
Load Pattern
On 10% Load
| Load Condition | Voltage | Voltage Harmonics |
|---|---|---|
| 55.38 VA | 227 V | 2.843% |
Voltage Harmonics Spectrum of UPS on 10% Load by SPEA-1
Comments:
- Vthd is 2.843%.
- Fundamental harmonics is 99.9 % of Vrms which is good.
- Third harmonics is 2.2%
- From 5th to 13th harmonics are less than 1% of Vrms.
- Other harmonics are zero.
On 20% Load
| Load Condition(VA) | Voltage | Voltage Harmonics |
|---|---|---|
| 124.78 | 227.3 | 2.611 |
Voltage Harmonics Spectrum of UPS on 20% Load by SPEA-1
Comment:
- Vthd is 2.611%
- First harmonics remain same on 99.9%.
- Third harmonic is also same on 2.2%.
- 15 to 25 harmonics are slightly increases.
- Others are zero.
On 25% Load
| Load Condition(VA) | Voltage | Voltage Harmonics |
|---|---|---|
| 153.9 | 226.3 | 2.755 |
Voltage Harmonics Report for UPS on 25% Load generated by SPEA-1
Comment:
- Vthd is 2.755%.
- Fundamental harmonic is remain same.
- Third harmonic increased by 0.1%.
- Others are same as previous.
On 40% Load
| Load Condition(VA) | Voltage | Voltage Harmonics |
|---|---|---|
| 194.53 | 223.6 | 2.835 |
Voltage Harmonics Report of UPS on 40% Load generated by SPEA-1
Comment:
- Vthd is 2.835%.
- Third harmonic is again increased by 0.1%.
- 5th to 17th harmonics are slightly increased.
On 50% Load
| Load Condition(VA) | Voltage | Voltage Harmonics |
|---|---|---|
| 302.8 | 222.8 | 3.596 |
Voltage Harmonics Report of UPS on 50% Load generated by SPEA-1
Comment:
- Vthd is 3.596%
- Third harmonic is also increased by 0.7 %.
- Harmonics from 5th to 15 are also increased.
- Others are zero.
Summary
- UPS showing overload on load over 300VA.
- As load increases THD increases.
- At load above 50% THD is greater than 3.
- 3rd harmonic is affected most (0.9% change).
Testing Instrument – SPEA-1
Test Done By – Himanshu Sharma (Electronic Testing)