500W Pure Sine Wave Inverter 12V*

1000W Pure Sine Wave Inverter 24V*

Pure sine wave power inverters offer the highest quality output that matches the quality of mains supply. House hold equipment are designed to operate on pure sine mains or it fails either instantly or a few days down the line. So the question really becomes do you save on the inverter cost now only to pay dearly for failing equipment tomorrow?

The units are designed to handle bursts of twice (200%) their rated capacity in order for pumps, power tools, heaters, fluoressent tube banks, PC’s (and hair dryers ;-) to start up every time and often. The latest solid-state components are used as the basis of each unit and no compromises are made in order for these units to operate 24 hours a day, 365 days of the year.

Input:
- 24V DC system
- Operating range is 23 –28V

Output:
- 230V ac pure sine wave at 50Hz
- Total Harmonic distortion (THD) less than 3%
- Rated sizes: 1000W continuous power handeling
- 200% surge power handeling

Protection:
- Low / under voltage alarm (UVA)
- Low / under voltage shut down (UVS)
- Over load protection (OLP)
- Over voltage shut down (OVS)
- Over temperature shut down (OTS)

Operating condition:
- Ambient temperature -10 to + 50 degrees centigrade
- Relative humidity 10% to 90%

* brand and size might vary due to specification and availability

500W Modified Sine Wave Inverter 12V* (ONLY AVAILABLE ON REQUEST)

* brand and size might vary due to specification and availability

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Inverters

There are many factors that go into selecting the best inverter (and options) for your application, especially when you get into the higher power ranges (800 watts or more). This page should give you the information you need to get your selection down to what will work best for you.

Sine wave, modified sine, square wave - say what???

There are two forms of electric wave output generated by an inverter, pure or true sine wave and modified sine wave. To understand the difference we need to look at their performance.

PureSine inverters

Pure Sine wave is the same as the power you have in your home. It is very clean and is the optimum for performance. Please take look at the graph below. You will notice the wave is very smooth. This smooth pure sine wave is most efficient. Therefore, appliances such as TVs, computers and stereos run cleaner and easier. Also, Pure Sine wave generates less heat than other waveforms.

Modified Sine wave or Square wave inverters

Modified Sine wave is an output that tries to imitate pure sine waves but comes up a little short. Nevertheless, modified sine wave inverters have their advantages. Modified sine wave inverters are great to run appliances and equipment such as power tools, non-digital microwave oven, lights, and other motor driven loads.

The main downside to modified sine wave output is slight interference. This interference can be seen on some televisions and computers. It will not cause any damage, but can be a little annoying. The upside to modified sine wave inverters is they will run most appliances, and are very affordable.

Sine Wave	Modified (Quasi) Sine wave	Square Wave

Watts - Or what size do I need?

The inverter size you choose depends on the power in watts (or current in amps) of the appliance/equipment you want to run (find the power consumption by referring to the specification plate on the appliance or tool or you will find the information in the appliance manual. If this information is not available, check the table above). You need to know both the continuous rating in watts or amps; and the peak/surge rating in watts or amps. Without this information any further calculation is not possible.

Typical power usage table

These figures are approximate representations. The actual power consumtion of your appliances may vary from these figures. Check the power tags on the appliances.

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CONTINUOUS vs PEAK/SURGE WATTS

Inverters are rated in continuous power and peak/surge power. Continuous power is the total WATTS the inverter can support indefinitely while peak/surge power is the amount of power that the inverter can provide for a brief period, usually when the equipment/appliance starts up. Induction motors driving such devices as air conditioners, refrigerators, freezers, pumps, etc. may well have a start up peak/surge of 3 - 7 times the continuous rating.

CONVERTING AMPS TO WATTS

Multiply the equipment/appliance AMPS x 230 (AC voltage) = WATTS (approximate)

WORKING OUT THE POWER

Multiply the equipment/appliance AMPS x 230 V (AC voltage) to give the approximate WATTS or AC power.

CALCULATE APPROXIMATE STARTUP LOAD (PEAK/SURGE WATTS)

Multiply the equipment/applicance WATTS x 3 = PEAK/SURGE WATTS (approximate)

So if you want to run an appliance with a continuous load of 5 Amps and a peak load of 15 Amps :
Power : V x I = VA i.e. 230VAC x 5A = 1150 Watts continuous power
Power : V x I = VA i.e. 230VAC x 15A = 3450 Watts peak/surge (also known as start or inrush current)

You would need an inverter with a continuous rating of approximately 1500 watts and with a peak/surge rating of approximately 3500 watts. It is always advisable to build in a safety factor by overrating the continuous rating by 20 - 25%

Peak Power vs Typical or AverageAn inverter needs to supply two needs - Peak, or surge power, and the typical or usual power.

• Surge is the maximum power that the inverter can supply, usually for only a short time - a few seconds up to 15 minutes or so. Some appliances, particularly those with electric motors, need a much higher startup surge than they do when running. Pumps are the most common example - another common one is refrigerators (compressors).
• Typical is what the inverter has to supply on a steady basis. This is the continuous rating. This is usually much lower than the surge. For example, this would be what a refrigerator pulls after the first few seconds it takes for the motor to start up, or what it takes to run the microwave - or what all loads combined will total up to. (see our note about appliance power and/or name tag ratings at the end of this section).
• Average power would usually be much less than typical or surge, and is not usually a factor in choosing an inverter. If you run a pump for 20 minutes and a small TV for 20 minutes during a one hour period, the average might be only 300 watts, even though the pump requires 2000. Average power is only useful in estimating battery capacity needed. Inverters must be sized for the maximum peak load, and for the typical continuous load.

Power Ratings of inverters come in size ratings all the way from 50 watts up to 50,000 watts, although units larger than 11,000 watts are very seldom used in household or other PV systems. The first thing you have to know about your inverter is what will be the maximum surge, and for how long. (More about 230 volts pumps etc later).

• Surge: All inverters have a continuous rating and a surge rating. The surge rating is usually specified at so many watts for so many seconds. This means that the inverter will handle an overload of that many watts for a short period of time. This surge capacity will vary considerably between inverters, and different types of inverters, and even within the same brand. It may range from as little as 20% to as much s 300%. Generally, a 3 to 15 second surge rating is enough to cover 99% of all appliances - the motor in a pump may actually surge for only 1/2 second or so.
• General Rules: The inverters with the lowest surge ratings are the high speed electronic switching type (the most common). These are typically from 25% to 50% maximum overload. This includes most inverters made by Statpower,  Exeltech, Power to Go, and nearly all the inexpensive inverters in the 50 to 5000 watt range. The highest surge ratings are the transformer based low-frequency switchers. This includes most Xantrex, Magnum, and Outback Power. Surge ratings on these can range up to 300% for short periods. While high frequency switching allows a much smaller and lighter unit, due to the much smaller transformers used it also reduces the surge or peak capacity.
• Pros and Cons: Although the high frequency switching type don't have the surge capacity of the transformer based, they do have some definite advantages. They are much lighter, usually quite a bit smaller, and (especially in the lower power ranges) they are much cheaper. However, if you are going to run something like a submersible well pump, you will need either very high surge capacity or you will need to oversize the inverter above it's typical usage, so that even at maximum surge the inverter will not exceed it's surge rating.