With constant power cuts, perceptions about the use of inverters in offices are changing. Inverters are slowly replacing gensets, which incur high maintenance costs. In many offices, inverters are catching up as an alternative backup power solution for non-critical applications such as emergency lighting and to run non-life supporting equipment in clinics and hospitals. High capacity inverters are also used to operate lifts, air conditioners, air coolers, elevators and even telecom applications. In small offices, it is used to operate EPABXs, phones, fax machines, laboratory equipment, etc.
By Srabani Sen
Wednesday, April 13, 2011: Inverters are cleaner than DG sets as they do not produce smoke. As some of the features are almost like UPS systems, they can be used in the SOHO and SMB sector as prime power backup devices.
Types of inverters required in offices
Modified sine wave power inverters, true sine power inverters and true sine wave high frequency inverters are used for office purposes. These are specifically designed for this segment and are ideal for charging batteries from either solar panels or external battery chargers.
Generally, inverters of 5-20 kVA are required in big offices and of 800-1400 VA capacity for small offices. For the latter, domestic inverters up to 5 kVA capacity can be used and for corporate offices, the requirement can go up to industrial grade inverters of 100 kVA. Square wave inverters, quasi square wave or modified square wave inverters and true/pure sine wave inverters are ideal for big offices.
The DC-AC power inverter/battery charger combination can be used as an extended AC power supply system. Combination power inverters have built-in battery chargers and transfer switches, which make them affordable and hassle free solutions for uninterrupted power requirements, giving an almost seamless power supply by switching over automatically.
The benefit of these power inverters over UPS systems is that you can size your own battery pack to get as many hours of backup as you need. They also have three times the power overload surge ability compared to most online UPS systems. The combination power inverter/charger units can be used in conjunction with very small and much more affordable UPS units, for the likes of computers, which require a very fast switch over function so that data is not lost.
What’s Hot & Innovative in the Market
With technology advancing at a fast pace, customers are demanding inverter solutions with advanced technology and want the most feature packed products, which has increased the competition in the market. However, most vendors are doing mere cosmetic changes to their products as inverters are very stable and their technology has remained nearly unchanged for years.
A new application is solar inverters, which are used as power backup devices, converting abundantly available solar energy to electricity. In the solar segment, another concept has evolved—that of grid tied inverters, which convert solar energy into electricity but feed it into the common grid instead of storing it in a battery. However, they still have limited business applications.
Most innovations for office inverters are related to increasing efficiency and stability. This helps in saving power as well as the environment. Innovations are also taking place to make inverters capable of charging fast and that enhance the longevity of the battery. Steps are also being taken to go for higher MTBF (mean time between failure) batteries, which save man hours.
Earlier, inverters were manufactured with quasi sine wave output but now they are being manufactured with the latest digital signal processing (DSP) based sine wave output. MOSFET based and IGBT based sine wave and high frequecy transformerless inverters are also in demand as they are small and occupy less space. The size of inverters is being reduced day by day, due to advances in technology. Another change is that, earlier, inverters were usually hidden somewhere in the office. But now manufacturers are coming up with aesthetically designed units, prompting users to display them.
Today, there is an attempt to build in UPS mode, which reduces the voltage window within limits and is acceptable to most SMPSs. There is also an attempt to reduce the transfer time to the acceptable limit of 19 minutes. These two features help in making the inverters compatible with PCs and servers in office environments. Besides this, some other features like load indication, battery charge indication and fault indication add to the convenience of knowing various environmental conditions.
Generator compatible inverters are the latest products in the power backup industry as they not only save power and reduce pollution but also cut down on the diesel cost. These inverters also provide relief during the switch over time from the main power supply to the generators. These inverter/generator combinations facilitate power savings of up to 50 per cent.
American Power Conversion (APC) offers 1 kVA-BI1000I inverters for offices. This inverter offers a pure sine wave output and uses two batteries (24V bus) to provide extended run time. “As desired by most businesses, we offer load indication, fault indication and faster transfer times to add to convenience,” says Gaurav Burman, director, transaction business, American Power Conversion.
Microtek International Pvt Ltd has a complete range of SOHO, hi-end and sine wave inverters in the 2.2 kVA to 10 kVA range, which are suitable for big and small offices. “These can even run air conditioners, LCD TVs, photocopying machines, etc,” informs Manoj Jain, vice president, Microtek International.
Lzen Electronics India’s ICON DSP based sine wave inverter with reliable, regulated, synchronised and stabilised pure sine wave output is a complete power system that is suitable for all types of offices, and is capable of running everything—from lights, fans, refrigerators, computers and fax, printers, to microwaves, air conditioners, lifts, etc, in a most cost effective manner. “These inverters are safe to run even sophisticated and sensitive office equipment. These inverters are energy efficient as the input efficiency is very high, which results in lower electricity bills. This helps in saving power as well as the environment,” says Manish Gupta, CEO, Lzen Electronics India.
Su-Kam’s DSP sine wave inverters in the Colossal series, are reliable, regulated and provide stabilised pure sine wave output, which are suitable for all types of commercial establishments and is capable of running elevators and welding archs. The Colossal series supplies pure power, which is 100 per cent safe to run even sophisticated and sensitive office equipment without any noise. The company has also created a pocket friendly 100 VA inverter, which is affordable for lower income groups. At the other end of its product range, it has refined the 500 kVA inverter for big offices.
“Su-Kam was the first to introduce DSP based sine wave inverter systems, specially designed for heavy duty retail and telecom applications, where we have provided an advanced solution as an alternative to generators,” informs Kunwer Sachdev, founder and managing director, Su-Kam Power Systems Ltd. For much higher requirements, Su-Kam’s Colossal range of inverters come in the 5 kVA to 100 kVA range. Its DSP sine wave inverter supplies pure power and is 100 per cent safe to run most sensitive office equipment without any humming sound. Its HF sine wave inverter, which uses state of the art technology, is for high frequency operations and requires less hardware, thus, reducing its weight and making it easily transportable. Its battery charger comprises an SMPS based topology which gives pure DC charging to the battery.
HULK solid state UPS systems are the new inverter cum UPS (2 kVA to 15 kVA) systems from Truepower International Ltd, and are used for small offices. Its three phase inverters from 10 kVA to 80 kVA are suitable for medium to big offices. “The unique solid state switching devices are used for fast changeovers without any spark and noise.” says Ravi Mundra, CEO, Truepower.
Uniline Energy Systems Pvt Ltd supplies inverters to companies that use single and three phase AC current. “Practically, inverters available for this purpose are available in any capacity and we can supply systems of up to 300 kVA,” says RK Bansal, managing director, Uniline Energy Systems Pvt Ltd. Its inverters are also used at the Taj Mahal, where generators cannot be used due to environmental issues.
Kevin Power Solutions Ltd offers single phase inverters called Static, ranging from 2.5 kVA to 12 kVA, informs Sujal Shah, CEO, Kevin Power Solutions. With this one product, you can run computers, lights, fans, ACs and office automation as well. “In Kevin Static UPS/inverter, we have not used any mechanical devise. It has one thyrister for changeover. So it is a highly electronic devise, hence very reliable and has less chance of failure,” as Sujal Shah. Kevin has two types of inverters—lighting load and compressive load. Its products can take 100 per cent load. The products are designed by using latest technologies like DSP, IGBT and multi-conversion technology with high end efficiency.
Convergence Power Systems Pvt Ltd has a range of inverters for offices including quasi sine wave in the 200 VA to 5 kVA range, sine wave regular inverters of 600 VA to 5 kVA and industrial grade heavy duty inverters of 5-60 kVA. It also offers DSP sine wave and DSP sine wave dual inverters and microcontroller based inverters. “We have introduced a solar cum utility power (dual charger) inverter for offices, ranging in capacity from 600 VA to 10 kVA,” points out Sree Kumar, director, sales and marketing, Convergence Power Systems Pvt Ltd.
upsINVERTER.COM’s sine wave combo UPS, which is based on microcontroller digital technology, has an inbuilt AVR that stabilises the input AC mains. Its highlight is a high frequency pure sine wave UPS system, and takes up very little space, hence, is suitable for offices where there is a space crunch. “This ‘Hi-Lite combo’ is noiseless and is also powered by microcontroller digital technology,” says Yogesh Dua, director, upsINVERTER.com.
Luminous offers pure sine wave inverters that are available with UPS applications as well. “These combos can be used for running computers in small offices. We also have inverters ranging from 3-20 kVA, depending on the load requirement of customers,” says Rakesh Malhotra, founder and managing director, Luminous Power Technologies Pvt Ltd. Luminous inverters up to 10 kVA have very low switching time, hence, they can be used for computers. “Considering inrush current requirement for motorised/lift load, we have 6 kVA three phase to 150 kVA three phase inverters,” informs Malhotra.
According to Amitansu Satpathy, director, Best Power Equipments India (BPE), a high power factor with reduced distortions and better efficiency, along with the lowest possible downtime, are some of the innovations taking place in inverters for offices. BPE offers full DSP controlled pure sine wave inverters in the 800 VA to 20 kVA range.
Type of customisation done
In this competitive market, where every company is vying for a greater share, many provide services like customised solutions, which are not only profitable but also a good brand building strategy. Hence, companies are offering out of the box solutions to suit Indian office conditions like power fluctuations, frequency variations, etc.
“Currently, most customisation happens in the size of batteries attached with the inverters. This depends on the kind of load that needs to be supported and the run time required,” points out Gaurav Burman.
Convergence makes design changes in the transformer to customise in terms of very low ‘no load current’ and to increase the efficiency of the inverters. Microtek, on the other hand, customises as per the buyer’s needs, which also includes customisation in charging currents and operating voltages.
Su-Kam has introduced customised products for various sectors such as retail, telecom, hospitality, commercial establishments, industrial units, banks, hospitals, etc. “We have recently powered Wal-Mart’s Easy Day retail chain and installed a three phase inverter system with multiple controlled output, where the distribution of the load was the priority, thereby reducing the running cost of the system by 30 per cent,” says Kunwer Sachdev.
According to Manish Gupta, there isn’t much scope for customisation in small inverters upto 5 kVA but in higher capacities, customisation can be as done as per the needs of the customer. “If a buyer requires a higher or lower number of batteries to take care of high surge starting loads, some changes can be made in input DC voltage. We can customise the charger banks depending upon the backup a buyer needs,” he adds.
Some of the customised applications Truepower has introduced are user friendly dual display (LCD and LED) that shows the exact conditions and help to diagnose the faults, and the use of computer loads mixed with lighting loads. Automatic charging selection according to the duration of the power cut and battery conditions is another customised feature.
Uniline can provide customised solutions if a customer needs higher outputs like 110 V for machines that are working at 110 V output only.
After sales support
After sales service is an integral part of any company’s offering and is almost as important as the initial purchase. If properly handled, service can be the key factor that drives growth for any manufacturer. But if ignored, it can cause a dent in the creditability of the brand. For customers, exceptional service is a rule not an exception. Anything less, they’re ready to change their brand. That makes extraordinary service necessary, not just desirable.
APC has a large ASP network that helps serve all customer requirements like installation support and even to get faster product replacement in the unlikely event of product failure. “Our call centres address every customer’s need. Besides this, we offer four free preventive maintenance checkups for the battery, which helps save it from dying early,” says Burman.
BPE provides free onsite after sales support during the warranty period and outside warranty periods, service is provided on call or based on the after sales maintenance contract (AMC). Microtek provides after sales support through its vast service network of 50 service centres and more than 305 service points in the country. While Kevin provides service support across India, Truepower provides services like pre-installation site checking by service engineers, when proper suggestions and customer education are provided.
Su-Kam has more than 200 service centres and invests a lot on training its service team. “We have extensive training programmes regarding servicing a product as well as product training programmes for our service engineers and channel partner’s service team,” says Kunwer Sachdev.
Lzen ensures that its customers get fast and prompt service. It also has a vast service network spread out in major cities.
Cost of installation and maintenance
Inverters are very cheap to install and maintain. Batteries are the only items that need constant topping up (which is actually very cheap to do). A typical installation involves load separation (between heating/high load and lighting loads). Depending on how much cabling needs to be done, installation can vary. Yet, it is not very expensive. Most inverters do not need any maintenance after being installed and they could run their lifetime without any trouble.
The cost of installing and maintaining inverters mainly depends on their capacity. But generally, the installation and maintenance costs are less than 10 per cent of the inverter’s cost.
Power saving features in inverters
Keeping up with the demand of customers, manufacturers now offer inverters with green technology that have power saving features. “Earlier, the efficiency of inverters was around 65-70 per cent but now they are being manufactured with more than 95 per cent efficiency. And more efficiency means more power saving,” says RK Bansal.
Points out Yogesh Dua, “High efficiency in DC-AC and AC-DC conversion, no load shutdown, optimised battery charging management and low internal power consumption in parts like the cooling fan, display, etc, are features that help in saving power.”
Sree Kumar says, “The fuzzy logic technology makes sure of less power drainage during charging. The high quality transformer designs also ensure a low load current.”
Ravi Mundra explains that power factor correction technology is used in inverters for power saving. The charger efficiency is improved by applying signature charging, which is the new age, complete automatic charging selection technology. In case of no load at output, the intelligent software inside the inverter senses the condition and goes into sleep mode (that is, the inverter stops discharging more).
Microtek inverters have high grade low watt loss core in transformers, which minimises watt loss and makes the inverters energy efficient. APC inverters, on the other hand, offer triple stage charging, which consumes lesss power to charge. This also helps in charging batteries faster, and therefore, an improved battery life. These inverters offer higher efficiency, which leads to lower power losses when the battery is being charged and even when the battery is being discharged to provide power. All APC inverters come with an A-way switch which allows the batteries to be charged but not discharged when the power supply fails. This switch has to be activated when the office is closed over the weekend. This feature helps conserving the charge on batteries, and therefore, saves power.
Su-Kam’s DSP sine wave inverters from the Colossal series produce pure sine wave. DSP technology meant for high speed data processing, in conjunction with sine wave technology, delivers an output which is completely stable and distortion free—with total harmonic distortion (THD)<3 per cent. This power is actually purer than power supplied from the grid.
Kevin’s automatic battery level management, high efficiency and low THD (total harmonic distortion) helps save power.
Luminous inverters have the latest technology to provide maximum output. “About 80-90 per cent of the time inverters run on the mains with more than 97 per cent efficiency,” informs Malhotra.
User friendly features in Inverters
Inverter systems are now very user friendly. They are fully automatic with digital display meters for users to see the parameters and functions. Inverters with a one-touch switch that does all settings and configurations are quite popular. In fact, after the installation of these inverters, users can relax. These units are also noiseless and pollution free. Systems also come with graphical and LCD displays.
Su-Kam’s digital inverter ensures user selectable heavy duty charger options that charge the battery 40 per cent faster than ordinary models. Its graphical display with audible alerts makes is very user friendly. It also saves space and has the option of a castor wheel mounted trolley for easy movement. Moreover, it has the capability to be upgraded in the future through digital flash memory. APC inverters have very clear and easy to understand indicators. Kevin and Convergence inverters are fully automatic, making them very user friendly.
Truepower’s HULK solid state UPS system has a wide charging range and complete automatic charging selection technology, making it easy to use. UpsINVERTER inverters are completely automatic and they can even sense low voltage in the mains supply and short circuits. These products rarely require any human interface.
Uniline inverters can display the necessary information with the help of LEDs/metering. You can also view and record the happenings of a full month. Lzen inverters are fully automatic with digital display meters for users to see all the parameters and functions, all of which are controlled by just a single switch. The inverter system also has a high and low charging switch at the back, which can be used by the customer as per the mode of battery used. Another feature is the inverter mode switch, which allows the user to select the input voltage windows to run the equipment.
What should a buyer consider while making a purchase decision?
Purchasing inverters for offices may appear a simple task but when you go shopping, you come across a large number of choices. Sometimes it can be difficult to know which features are important and how to choose the right product for your needs. While wattage, features and connections are obvious considerations, your final choice should take into account the inverter’s wave form output.
Once you have decided to buy an inverter, think about what power (wattage) it should be carrying. The total wattage is calculated as a product of current and voltage (that is, AMPS x voltage = watts). It is wise to purchase a larger power inverter than you need.
When purchasing a modified square wave or a pure sine wave inverter, you must consider which appliances you intend to power. A pure sine wave inverter can power any device/appliance which can be powered by mains electricity—but a modified square wave inverter cannot. For example, desktop computers can be powered by a modified square wave inverter but the monitor may make an audible humming sound.
The buyer must consider the energy efficiency (that is, how much electricity is consumed during the use) of the inverter and the life of the battery. After sales support and the price received during disposal are some other key factors to be considered.
The inverter should provide protection against overload, low battery, short circuits, etc. Buyers should also check if the inverter can work with all types of batteries such as flat plated, tubular and valve regulated maintaince free batteries.
It is advisable to do a comparative survey before making the purchasing decision. Also, understand your power requirements.
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very good blog about inverter