Considering the unsuitability of Square Wave and Modified Square/ Quasi Sine/ Modified Sine Wave UPS/ inverters for most of the Electrical/ Electronic Appliances, the demand of Sine Wave UPS/ Inverter, which can provide the good quality of power to all Electrical/ Electronic Appliances. Using sine wave UPS/ Inverter, we can get same performance of sophisticated Electrical/ Electronic Appliances as on Mains Grid Power. Also on Sine Wave UPS/ Inverter, service life of sophisticated Electrical/ Electronic Appliances do not deteriorate.
In above two major types, Sine wave inverters are superior in quality and performance. It doesn’t mean square wave inverters are inferior, square wave or modified sine wave inverters have their own specialties. But the fact, all of us should accept is ‘sine wave inverters are better than square wave or modified sine wave inverters’.
To get the Pure Sine Wave at the output of the UPS/ Inverter, advance technology has to be used. To generate Pure Sine Wave, Advance Digital Signal Processing (DSP) Technology is required, for that DSP chip is being used now a day. DSP Chip along with dedicated hardware and software using high frequency PWM Technology used to produce Pure Sine Wave at the output. A special dedicated algorithm also used to control the charging the Power Battery smartly using the same DSP chip. It enhance the battery life significantly up to 1.5 times.
Not actually, it depends upon the design and technology. But because of market pressure of reducing the cost of UPS (to make the UPS most competitive), less efficient transformer is being used in the UPS causes less overall efficiency. By using efficient transformer, the efficiency of DSP based Sine wave UPS can be increased. EAPRO is using Copper Transformer to make the UPS more efficient.
Sine wave UPS gives extended power back up compared to modified sine wave of square wave inverters. It saves your current bill.
Square wave UPS/ Inverters are First generation UPS/ Inverters. These are cheapest inverters available in the market. Modified Square wave/ Trapezoidal wave/ Quasi Square/ Modified Sine wave UPS little costlier than the square wave UPS. But Sine wave UPS/ Inverter are best in performance and also in the same price band as Modified Square wave/ Quasi Square/ Modified Sine wave UPS.
Square wave UPS/ Inverters are VERY noisy. OK for apps like lighting, heating, running motors etc. only, while Quasi Square/ Modified Sine wave UPS are having little less humming noise but less efficient in comparison to Square and Pure Sine Wave Inverter/ UPS. But Sine wave UPS/ Inverter widely recommended and suitable for all type of AC equipments (Home appliances/ PCs/ Motors/ lifts etc.). The output of Sine wave UPS/ Inverter is similar to Main Grid Power. It does not produce any Noise. Sine wave UPS/ Inverter is completely appliance friendly as the power produced is similar to Mains Grid Power.
Sine wave inverters are the best. They utilize sinusoidal PWM to produce a CLEAN sine wave which is equivalent to Mains Grid Power. The circuitry of Sine wave UPS is a lot more complex than the square wave, but because of very less distortion, it doesn’t produce any humming noise. Most sensitive equipment like Wi-Fi’s, PC’s, medical equipment etc. can be connected to Sine Wave Inverter/ UPS.
You can operate Mixie or Grinder safely with sine wave inverters. (850 VA inverters and above)
Inrush current, input surge current or switch-on surge refers to the maximum, instantaneous input current drawn by an electrical device when first turned on. For example, incandescent light bulbs have high inrush currents until their filaments warm up and their resistance increases. Alternating current electric motors and transformers may draw several times their normal full-load current when first energized, for a few cycles of the input waveform.
The crest factor and the peak currents of a load are important considerations in power source selection. Crest factor is defined as the ratio of peak value to rms value of a current waveform
Crest Factor = Peak current in Ampere / RMS Current in Ampere
The crest factor for a sinusoidal current waveform, such as that which a pure resistive load would draw, is 1.414 since the peak of a true sinusoid is 1.414 times the rms value. However, the crest factor for a non-sinusoidal current waveform can differ dramatically for loads that are not power factor corrected, such as a switching power supply or lamp ballast, which give a current waveform that is short in duration but high in amplitude.
The ratio of the UPS output power to the UPS input power is called efficiency of UPS/ Inverter. The UPS efficiency varies depending on its load factor.
% Efficiency = [UPS output power (in kVA) ÷ UPS input power (in kVA)] x 100
Generally, 85% efficiency is considered as Standard, 90% efficiency is considered as Good and >95% efficiency is considered as Best efficient UPS.
Total Harmonic Distortion is an important factor while selecting a suitable UPS based on its application. It is a measure of the ratio between the fundamental and the harmonics that are present in a waveform.
The presence of harmonics in AC voltage waveform changes its wave shape from a simple sinusoidal to complex waveform. Distortion in the output Sine Waveform, generally transmitted by non-linear loads (like Computers, Switch Mode Power Supplies, Variable Speed Motors and Drives, Copiers and Fax Machines etc.).
A Sine Wave UPS/ Inverter has AC Harmonic content (THD-Voltage) <= 3% for linear load and <=5% for non linear load.
Because of presence of High level Harmonic Distortion in square /Modified Square wave/ Trapezoidal wave/ Quasi Square/ Modified Sine wave Inverter/ UPS, all the non-linear loads like fans, electronic blast of florescent lights, Switch mode power supplies, variable speed motors and drives, copiers and fax machines create humming noise.
Few Facts
Some company claims for Trapezoidal wave UPS/ inverter, but it is actually a Modified Square wave/ Quasi Square/ Modified Sine wave UPS/ Inverter. Some company promote their product as Modified Sine Wave, some promote as. But the fact is all these type of Inverter generate same output wave, which is Quasi Square Wave, which is inferior than Pure Sine Wave in all respect.
Parameters |
Square Wave UPS |
Modified Sine Wave/ Modified Square Wave/ Quasi Wave UPS |
Sine Wave UPS |
Remarks |
Technology |
Crude Technology |
Moderate Technology |
Adv. DSP based PWM Technology (20 KHz Switching Freq.) |
– |
Audible and electrical Noise |
Very High |
High |
No Noise |
Noise is harmful for the life of the appliance. |
Suitable for Sophisticated Electrical appliance |
Not suitable |
Not Suitable |
Suitable |
Pure Sine Wave supply is most suitable for any electrical Appliances. |
Total Harmonic Distortion (THD) |
Very High |
High |
Low (< 3% on Resistive Load) |
High Distortion is harmful for the life of the appliance. |
Crest Factor (Capability to Handle Inrush/ Surge Current) |
Very Low |
Very Low |
Good (3 : 1) |
Good Crest Factor beneficial for Inductive/ moterised load (Electronic blast of tube light, SMPS, Motor Drives etc.) |
Efficiency |
Upto 80% |
< eff. of Square Wave UPS |
85 to 88% |
More energy efficient means money saving |
Square Wave Inverter/UPS
Modified Sine Wave/Modified Square Wave/Quasi Square Wave/Trapezoidal Wave Inverter/UPS
Sine Wave Inverter/UPS
High Frequency Sine Wave Inverter/UPS
Advantages of Sine Wave Inverter