Pengenalan
If you are a B2B buyer who is purchasing power inverters for industrial equipment, telecommunications computer rooms or backup power systems, you may also be thinking about a question: “How much power should you buy?” It sounds quite simple, but it’s not so intuitive to answer.
If you choose the wrong size of the inverter, it will be quite troublesome. If you buy a small one, you can’t carry the device at the critical time, which will directly trigger the overload protection and stop the operation. If you buy a large one, you will spend more money on the hardware, the no-load power consumption will be high, and the battery capacity will be wasted.
This guide will take you through a five-step process to help you choose the right size of the inverter. You will learn how to calculate the actual power requirements, how to distinguish between operating power and surge power, and finally choose an inverter that can keep the operation running steadily.
Why Correct Inverter Sizing Is Critical
Choosing an inverter is not only to turn on the light, but also to choose the right size, which is directly related to the stability of the operation, how long the equipment can be used, and how much it costs in total.
Choosing a small inverter is the most common and the most lossy practice. If the load exceeds its continuous power, the equipment will overheat or trigger the protection circuit. In industrial occasions, a minute of downtime may cause a loss of thousands of dollars. A tripping of the inverter is not only troublesome, but also may have a great impact. Some motors have a particularly high current when starting. Even if the power looks okay when running, the smaller inverter may jump directly.
There is also a problem with the large selection of inverters. The capacity is not enough, but it costs more money. If the inverter is too large, the no-load current is also large, and the battery’s electricity will be consumed in vain, and the overall efficiency of the system is low.
Foundational Concepts Before You Start Calculating
Before starting the selection, there are a few basic concepts that need to be understood first. If you understand these, it will be much clearer.
Watts, Volt-Amps, and Power Factor
Watt (W) is the actual power, that is, the part of the electricity that actually does work. Volt-ammere (VA) is the power, including the actual power and the part that does not work. The relationship between the two is determined by the power factor (PF). Watt is equal to volt-ammere multiplied by the power factor.
Pure resistance loads such as light bulbs and heaters, the power factor is close to 1.0, and the watt and volt-ampere are almost the same, but the motor, transformer, and some electronic devices are inductive loads. The power factor is generally between 0.7 and 0.9. If the power factor of a 10kVA inverter is 0.8 In the case of 5, the actual output can only output 8.5kW of power. If your equipment is marked as volt-ammere, you must first use the power factor to calculate the power factor into watts before calculating the size of the inverter.
Running Watts vs Starting Watts
Running watts, also known as continuous power, is the electricity that needs to be consumed when the equipment is operating normally. A 1.5kW pump is always using 1.5kW when it is on.
Starting watts,also called surge power or peak power, which is the short-term power impact required by some equipment when it is just started. Motors, compressors and pumps may require two to three times the operating power when starting. If a 1.5kW blower motor is started directly, the inverter may need to It can carry more than 6kW of power in those two or three seconds.
When selecting the inverter, it should not only be able to carry the total operating power of the equipment running at the same time, but also be able to withstand the one with the largest start-up impact.
Simultaneous Load vs Maximum Demand
Choosing an inverter does not include all your equipment, but only those that will be turned on at the same time. If you never use the microwave oven when the air compressor is on, you don’t need to add both when counting the total operating load. Just estimate according to your actual usage. Don’t think too full.
The 5-Step Inverter Sizing Process
Step 1 — Create a Complete Equipment Inventory
First, list all the equipment you will open at the same time, including large motors, industrial equipment, lighting, control systems and communication equipment. Note the name and model of each device, how many there are, and whether there are motors or compressors. This list is the basis of the whole selection. If any of them is omitted, the inverter may be bought too small.
Step 2 — Find Nameplate Ratings for Each Piece of Equipment
Find the nameplate or specification label on each device, which can generally be found on the back, bottom or in the instruction manual.
Record the following:
- Running watts(or “rated power,” “continuous watts”)
- Voltage and current(if watts are not listed, calculate: Watts = Volts × Amps)
- Surge watts(or “starting watts,” “peak watts,” “locked rotor amps”)
- Faktor kuasa(if the device is rated in VA)
Don’t rely on guessing. The parameters on the nameplate are the most accurate. If there is no surge power, the equipment with a motor is generally estimated as two to three times the operating power.
Step 3 — Calculate Running Wattage Total
Add up the operating power of all simultaneous equipment.
For example:
- LED lights: 100W
- Control system (PLC/HMI): 200W
- Small pump (running): 800W
- Network equipment: 150W
Total running watts = 100 + 200 + 800 + 150 = 1,250W
If the equipment is marked as voltampere, remember to multiply the power factor and calculate it into Watt.
Step 4 — Identify and Calculate Surge Wattage Requirements
Find out the device with the most power to start from the list. Generally speaking, you only need to consider the biggest surge, because it is unlikely that all heavy equipment will start at the same time at the same time.
Using the example above:
- LED lights: 100W running, no surge
- Control system: 200W running, no surge
- Small pump: 800W running, 2,400W surge (3× running)
- Network equipment: 150W running, no surge
Required surge capacity = 2,400W (the pump’s surge) + (100 + 200 + 150) = 2,850W total peak demand
Some experts recommend a simpler approach: add all running watts plus the highest single surge wattage. The inverter’s peak power rating must exceed this value.
Step 5 — Apply Safety Margin and Select Your Inverter
Don’t let the inverter run with 100% capacity all the time, which will heat up and have a short life. On the basis of the total operating power, 20% to 25% of the margin will be added.
Using the example:
- Total running watts: 1,250W
- With 20% margin: 1,250 × 1.2 = 1,500W minimum continuous rating
- Required surge capacity: 2,850W minimum peak rating
Choose an inverter with:
- Continuous power rating ≥ 1,500W
- Peak/surge power rating ≥ 2,850W
For key industrial applications, it is recommended to leave a margin of 25% to 30% to cope with efficiency loss, later equipment and high-temperature environment.
Common Sizing Mistakes That Lead to Costly Problems
Ignoring Motor Starting Currents
This is the most common and the most unfortunate mistake. When the motor, pump and compressor start, it uses two to three times more electricity when it is running. If the inverter cannot withstand this short surge, it will trip and shut down. Be sure to compare the surge rating of the inverter with the highest motor start-up requirements.
Using Nameplate Watts Without Considering Power Factor
If the equipment is marked with volt-ampere instead of watts, it has to be multiplied by the power factor. If the load power factor of 5000 volt-amperes is 0.85, it is actually only 4,250 watts, but if 5000 volt-amperes are counted as 5000 watts, the inverter will be smaller.
Forgetting Future Expansion Headroom
This is a common problem. If you add a device later, you may have to replace the whole inverter. It will save a lot of trouble if you leave extra capacity from the beginning. 20% of the safety margin is useful, but if you expect a significant increase in the future, leave more.
Not Accounting for Environmental Derating
When the temperature is high, the efficiency and output power of the inverter will decrease. Most inverters begin to decrease when the ambient temperature exceeds 40°C. When it reaches 50°C, the output may decrease by 20% to 50%. If the inverter is to be installed in a place with a high temperature, it must be selected according to the environmental reduction, or choose a wider working temperature range.
Assuming All Equipment Runs Simultaneously When It Doesn’t
If you add up all the equipment instead of just the part that will be opened at the same time, the inverter will be too large and waste money. Just estimate it according to your actual usage. Don’t think too full.
Soalan Lazim
What happens if an inverter is undersized for the load?
If you buy a small one, the inverter will overheat, trigger protection or shut down directly. If you have a motor, you may not be able to start it at all. If you use it on critical occasions, you will lose a lot of downtime, and the equipment may also fail.
Does inverter derating apply in hot environments?
Yes, most inverters will start to reduce the power when the temperature exceeds 40°C. If the temperature is higher, the output will be more. When selecting the model, remember to check the reduction curve in the manufacturer’s data manual. If the temperature of the installation place is high, the margin should be left accordingly.
Why Partner With WEHO?
WEHO has been making power conversion equipment for nearly 20 years. It has ISO 9001 certification. WHP series pure sine wave inverters range from 300W to 6000W, which can convert 12V, 24V and 48V direct current into 100V to 240V alternating current, and the efficiency is more than 90%. Load, short circuit, overtemperature and low-voltage protection are all included. All full-load ageing tests are done before leaving the factory. WEHO’s technicians can also help you choose the right model for specific applications. If you need it, you can contact us directly.
Kesimpulan
Choosing the size of the inverter is actually not complicated, but you have to take every detail seriously. First, list all the equipment clearly, check the operating power of each unit and the surge power under the start, add up the load at the same time, find out the largest surge, and leave a margin of 20% to 25%. At the same time, be careful of several common pits. , don’t ignore the starting current of the motor, don’t forget the conversion of the power factor, don’t ignore the impact of the high-temperature environment on the output, and don’t forget to leave space for the equipment that may be added in the future.
For B2B buyers, choosing the right size means that the operation is more stable, the equipment can be used for a longer time, and the total cost is also lower. WEHO’s pure sine wave inverter product line is very complete, and the power, efficiency and protection functions can meet the needs of industry and commercial occasions. Hubungi WEHO now to help you select and find the right one. The one in your project.
