Today demand of pure sinewave inverter/UPS is increasing beacuse square wave UPS/Inverter can not run various equipments. So we have taken a sinewave UPS for testing. 

We can know the purity of sine wave inveter by harmonics analysis. A square wave inverter has very high voltage THD at output whereas pure sinewave 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%

Comments –  

1. Vthd is 2.843%.
2. Fundamental harmonics is 99.9 % of Vrms which is good.
3. Third harmonics is 2.2%
4. From 5^th to 13^th harmonics are  less than 1% of Vrms.
5. Other harmonics are zero.

On 20% Load

Load Condition(VA)	Voltage	Voltage Harmonics
124.78	227.3	2.611

Comment –

1. Vthd is 2.611%
2. First harmonics remain same on 99.9%.
3. Third harmonic is also same on 2.2%.
4.  15 to 25 harmonics are slightly increases.
5. Others are zero.

On 25% Load

Load Condition(VA)	Voltage	Voltage Harmonics
153.9	226.3	2.755

Comment –

1. Vthd is 2.755%.
2. Fundamental harmonic is remain same.
3. Third harmonic increased by 0.1%.
4. Others are same as previous.

On 40% Load

Load Condition(VA)	Voltage	Voltage Harmonics
194.53	223.6	2.835

Comment –

1. Vthd is 2.835%.
2. Third harmonic is again increased by 0.1%.
3. 5^th to 17^th harmonics are slightly increased.

On 50% Load

Load Condition(VA)	Voltage	Voltage Harmonics
302.8	222.8	3.596

Comment –

1. Vthd is 3.596%
2. Third harmonic is also increased by 0.7 %.
3. Harmonics from 5^th to 15 are also increased.
4. Others are zero.

Summary –

1. UPS showing overload on load over 300VA.
2. As load increases THD increases.
3. At load above 50% THD is greater than 3.
4. 3^rd harmonic is affected most (0.9% change).

Testing Instrument – SPEA-1

Test Done By – Himanshu Sharma (Electronic Testing)

Download Harmonics  Spectrum Report