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Size matters when it comes to generators. This will determine how much power your generator can produce and how much load it can carry. But choosing the size is more complex and meticulous than just going by the “bigger is better” philosophy. It may do more harm than good if you don’t calculate for an accurate load-size ratio.

The Consequences of Improper Sizing

The improper sizing of an industrial generator is a common mistake among business owners. Businesses sometimes acquire a generator larger than their current needs as a projection of their long-term growth. A generator must use at least 35 percent of its load capacity. Otherwise, it can lead to wasteful inefficiencies and wet stacking.

Wet stacking occurs when a generator has too light a load. As a result, the engine’s operating temperature doesn’t get high enough to burn the diesel fuel entirely. The unburned carbon or fuel, or both, accumulates in the exhaust system. This can lead to bigger problems, such as fires from fuel leakage, permanent damage on the engine, and reduced turbo efficiency.

On the flipside, overloading a generator may cause unexpected system failures, reduced generator lifespan, and breakdown in oil consistency. It can also lead to overheating of the engine and alternator, which may result in electrical fires.

Professional generator repair services can remedy the damage caused by improper sizing. But proper maintenance and load calculation still trump repairs any time. Follow this three-step generator sizing guide to avoid problems with your machine and delays in your operations.

1. Calculate the load size

Identify the equipment your generator will be running and add the total wattage. This will tell you the amount of electrical power your equipment needs, which will help you determine the minimum input you require from a generator.

Some devices have different starting and running wattage since it generally takes more power to start a piece of equipment than to keep it running. Account for these initial power surges to make sure your generator has enough power to start the load.

2. Convert the wattage to kVA

The total wattage of your equipment will give you your minimum power requirement in kilowatts (kW). Generators use a kilo-volt-ampere measurement, so you have to convert your required kW to know how powerful you need your generator.

Diesel generators typically have a power factor of 0.8, which represents the efficiency of the electrical system. Compute for the kVA by dividing your total kW by the power factor. For example, your required wattage is 100. Divide this by 0.8 and you have 125.

This means that you need a generator that could produce at least 125 kVA.

3. Define your running requirements and projected growth

Since you can’t run a generator at maximum capacity for more than 30 minutes(otherwise, it will get overloaded), you’ll need more than a 125 kVA generator. It isn’t enough to use as your main power supply. Size for a 70 to 80 percent capacity, with the remaining 20 to 30 percent serving as your safety margin.

Also, allot for additional equipment if you’re planning to get more soon. Decrease your capacity to about 50 to 70 percent to anticipate the extra load, depending on how many equipment you’re expecting. But make sure to keep your generator running on at least 35 percent load capacity to prevent wet stacking.

Sometimes, generators break down unexpectedly, even if you’ve followed all the necessary steps. When this happens, consult with a professional generator repair service.

When Dealing with Generator Failure

Old rusty generator

Quality Electric Sales and Service has a team of technicians who perform diagnosis and repairs for AC and DC motors, including generators, traction motors, and variable speed motors, among others.

For your generator repair needs, request a quote today.

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