Boiling summer just few weeks ahead, scheduled and unscheduled power cuts are expected as usual. Inverter are one of the most demanded products of summer season. Are you planning to buy or upgrade your inverter in this season? Then instead of being trapped in the marketing gimmicks, understand some basic facts and do a little bit home work. Here some facts you must know before buying an inverter or UPS !?
Before going to purchase an inverter- You have to make a rough estimation of your power requirements. remember- Inverter is not a Generator. Inverter has it’s own limitations. You can’t power and run your complete home with a normal inverter. If your power requirement is more than 3000 VA, then an inverter alone can’t cater your demands effectively. No doubt a high power inverter can run your refrigerator and air conditioners, but how long? Here your battery will not last more than few hours. Hence it it better to go for a home generator. However if you don’t want a single minute power downtime, then a power inverter – electric generator combination is a good option.
You can also calculate our automatic load calculator click here….
Starting power and running power ?
Starting and running power requirement of all electric appliances are different. An 18 Watts CFL takes around 25 Watts power to start and after few seconds it stabilizes to 18 Watts. Some appliances like Refrigerator, Washing Machine etc take almost double power to start as compared to the normal running power. Hence before selecting an inverter you must calculate the starting power requirement also.
Often people confuse with the difference between Watts and VA ratings of inverter or other home appliances. Manufacturers use both these terms according to their requirements to confuse and mislead the consumers. Power drawn by the equipment (Power using equipment like Bulb, Fridge, Washing Machines, ACs, Stabilizers etc.) and Power generated by the equipment (Generators, Inverters, UPS etc) can be expressed in Watts or VA (Volt Ampere). In general Power generating or stabilizing equipment manufacturers use the term VA to specify their ratings and power consuming products use Watts to specify their ratings. Here comes the difference. Power in Watts is the real power drawn or supplied by an equipment, this is the real value. VA is the apparent power (more theoretical) which is obtained by multiplying the Voltage and Current drawn/supplied by an equipment. We can equate the VA and Watts ratings:
The ratio of Power in Watts to Power in VA is termed as Power factor. Unfortunately manufacturers often don’t specify the power factor or efficiency in their products.
Let’s see an example. You are purchasing an inverter with 650 VA power ratings. This 650 VA indicates, it can supply 650 VA power under ideal situations( means efficiency of the inverter is 100%). If we take 80% as a typical efficiency figure, the said inverter can supply 80% of 650 = 520 Watts only. Now you can understand why inverter manufacturers only publish the VA rating on their products. If an inverter or UPS is coming without mentioning power factor, you must take a safe value of 0.6 (60%) as power factor while connecting appliances.
Select Right Battery Capacity ?
Capacity of a battery is expressed in terms of Ampere Hour (Ah). It indicates the rate of current a battery can supply for a given duration. If the capacity of a battery is 100 Ah, that battery can supply 100 Ampere current for 1 Hour or 1 Ampere Current for 100 Hrs, 2 Amps Current for 50 Hrs .Capacity of inverter batteries are generally 100 Ah, 150 Ah or 180 Ah.
You also watch our YouTube Channel “Electrical Learner” and watch How to calculate Inverter load?
Why automotive batteries are not suitable for inverters?
Lead acid batteries used for automotive purpose are termed as “High Cycle” lead acid batteries. These batteries are designed to provide high current for a very short duration (To start the vehicles). Automotive lead acid batteries are not designed to be regularly discharged by more than 25% of their rated capacity. Here the requirement of inverter is totally different. Inverter require “Deep Cycle” type batteries to provide continuous power which can be discharged at least 50% of their rated capacity. Some good deep cycle batteries can be discharged over 80% of their capacity. Deep Cycle batteries have specially designed thick plates to withstand frequent charging and discharging.
Maintenance Free batterie ?
Lead acid batteries require regular maintenance. You have to check the electrolyte level and require to be topped up on regular intervals. Moreover these batteries release poisonous gases during charging and discharging. If you don’t keep the batteries in a properly ventilated place, it can invite serious health problems. You have to keep the terminals of normal lead acid batteries corrosion free by applying petroleum jelly or grease regularly.
Maintenance free batteries are sealed lead acid batteries which do not require topping up or additional ventilation.
Tubular batterie ?
This is the most popular segment of inverter batteries-Tubular batteries have several advantages compared to flat plate batteries. More complex design increases the manufacture cost but the high electrical efficiency and extra long life make tubular batteries suitable for both domestic and industrial applications. A good maintained tubular battery can run unto 8 years or more. Tubular batteries comparatively require less maintenance. Cost of tubular batteries can go up to double of a normal flat plate battery, however if you have a high efficiency inverter then go for a tubular battery, you will not regret. Almost all popular battery brands in India like Exide, Luminous, Microtek, Amaron etc have specially designed tubular batteries for inverters.
Select Right Inverter output (Sine wave, Square wave, Stepped Sine wave) ?
Our commercial power supply is 50 Hz pure sine wave (see the figure). However most of the inverters don’t output pure sine wave. Old inverters generate 50Hz square wave or 50Hz modified Sine wave (Quasi Sine wave , Trapezoidal wave or Stepped Sine Wave). Then the question comes. This wave shape really matters? Yes it does.
All commercial instruments are designed to run on pure sine wave. Characteristics of such devices are greatly depend upon the input wave shape. A change in wave shape will affect the performance of the appliances. Appliances like Motors, refrigerators, Ovens etc will generate full power on pure sine wave input only. Distortion in the sine wave creates humming noise in transformers, and audio devices. Some instruments like light dimmers, few battery chargers, toasters etc require pure sine wave to work. Prolonged operation of appliances in Square or stepped waves will considerably affect the life of such equipment due to the generation of heat.
You may be noticed that audio amplifiers, Televisions, Fluorescent lamps etc make noise on inverter power. This indicates that inverter output is not pure sine wave. Sine wave inverters are costly as compared to square wave and stepped sine wave inverters, however it is always advisable to go for a pure sine wave inverter for the safety and effective performance of your appliances.
Power Consumption of inverter ?
Inverters take mains power supply to charge the batteries. If the charging section of an inverter is not energy efficient, it will waste electricity even after the battery is fully charged. This will inflate your electricity bill. It is very difficult to check this aspect in shop before purchasing an inverter. However you can test the same at your home. Switch off all appliances except the mains supply to inverter, disconnect the battery and measure the power consumption for a specific period.
Check After Sales Support ?
We can’t give a blanket suggestion in favor of a particular brand or model. All electronics equipment are prone to damage, hence after sales support is always paramount which varies from place to place. As inverters are static devices, go for a dealer or brand who offers on site warranty repair and maintenance.