backup diesel power generators

Industry Backup Generator Standard Sizes

Industries are unique when it comes to power needs. The amount of power used depends on operational factors and the surrounding environment. In times of need, efficient and reliable backup generators can make a difference. Thus, it is important to know how much power is needed to ensure its optimum performance.

Diesel power generators in a factory.


Why Need a Backup Generator?

Backup power is crucial during a power outage. When extended outages occur, most businesses will be forced to close if there is no available generator. The use of commercial generators can keep the business running and prevent losses associated with these power outages. But this can only happen when the generator used is properly sized.


Types of Industrial Generators

Industrial generators come in two types – natural gas and diesel generator. Natural gas generators are connected to the gas line to create a readily-available fuel source. They cost less and don’t produce pungent odor associated with fuel consumption. Using this type, however, offers a shorter life span and requires more maintenance. Diesel generators are smaller, safer, and require less maintenance. They are less flammable and less explosive. However, diesel engines may experience problems during fuel costs fluctuation.


Industrial Generators Size

Homeowners looking for standby power may choose between a portable generator or a standby generator. Recreational units run from 2kW to 2000 watts while portable generators for houses can reach up to 50kW. Typically, these generators use a single-phase mechanism to supply power to smaller equipment.


Industrial generators are large, stationary, and heavy-duty systems that generate single-phase or three-phase power for the highest peak demand and power solutions. They produce a huge amount of uninterrupted power with an automatic transfer switch to immediately start a backup when electricity fails. Technological advancements produce units ranging from 20kW to over 3MW.


Generator Sizing

In determining generator size, power requirements are needed. Make a list of the devices and the estimated amount of watts required to start each of them. A running generator must utilize at least 35% of its load capabilities.


Buying too large is a common mistake since a generator running with too light of its required generator capacity may result in wasteful inefficiencies and serious damage. Meanwhile, a generator that is too small to handle the load can cause detrimental damage to the unit and the connected assets.

To calculate the correct size of the commercial generator, the following methods can be used.


Industrial Generators Sizes


Full Load Capacity

A. Measurement

  • Check the full-load current measurements during peak usage. At the service panel, apply a clamp-on ammeter to each arm of the electrical service. Add the measurements to get the total amps used.
  • Divide the value by two to get a single-phase current or by three for a three-phase current. Multiply the number with the supply voltage and by 1000 to get the kilowatts required.
  • Consult the National Electrical Code to determine the full load kilowatts needed for each emergency safety system. Multiply the full load capacity by 0.25 to get the reserve capacity. Use the equation total amps x supply voltage/1000 = full load kilowatts.
  • Add the full load capacity and the reserve capacity to get the generator size needed to provide total power.

B. History

Most companies include the peak demand on their monthly bill to get the maximum power usage. This will be adjusted to an additional 25% to determine the reserve capacity.


C. Extensive Motor Use

Find the starting current for the largest motor and multiply the value to the voltage to get the watts required. Multiply the current with the voltage for all the motor and non-motor load. For the largest motor and all other remaining motor and non-motor loads, multiply the value by 1000. Add 25% for reserve and determine the size generator according to the result.


Square Footage Sizing Method

  • For retail applications such as grocery stores, convenience stores, and other commercial applications, estimate 50 kilowatts and add 10 watts for every square foot of space.
  • For a commercial application such as office buildings, estimate 50 kilowatts and add 5 watts per square foot.


The Expert Advice

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