How Do You Size A Generator For A Building?


Getting a generator which can meet all your power generation needs is some of the most critical aspects of buying decisions. If you’re interested in prime or standby energy, if your new generator is unable to meet your particular needs then it actually won’t do anyone any good because it can place undue stress on the system and even damage any of the devices connected to it. Unfortunately, deciding exactly what generator size to get is also very difficult and requires a variety of variables and considerations.


Choosing between single-phase, three-phase, kW, KVA, welder, standby or engine-start generators may be mind-boggling. This article was developed to help you get a better idea of how the process of sizing works, and to keep in mind some key things to avoid such confusion. This is not a substitute for a certified electrician, with whom we always suggest speaking before buying, but it should give you enough information to get a solid understanding of some of the key things involved.


Generator Size Variations: Generators are now available in a large variety of sizes, with the latest electrical engineering developments. Generators with a power supply range of 5kW to 50kW are readily available in the personal and home use sectors, whereas industrial generators are available anywhere from 50kW to over 3 Megawatts. To homes, RVs and small offices, convenient and compact gensets are available, but larger enterprises, data centers , warehouses, hospitals, and industrial applications need to use much larger industrial generators to meet their higher power needs.


Sizing Generator-How much Power?: Some people assume that smaller generators are to be used for standby power, because they don’t always work. This isn’t just a myth but in reality it can be very harmful. Unfortunately the generator under sizing is one of the most common errors that buyers commit. Not only does it include the risks of losing the new product (the generator), it can also damage other associated properties, create hazardous conditions and even decrease the overall performance of the system and/or the business that relies on them. If nothing else, the key thing to remember here is that more is always better than less.


How to Determine the Right Size Engine or Generator: Although there is no substitute for having a professional electrician perform an inspection and decide it for you, the instructions below include some excellent starting points so you can at least start in the right direction:


Know Your Requirements: The best way is obviously not to go to a dealer without any other thought and buy the best or cheapest generator available. It’s always best to dig deep into the power generation requirements before making a decision. They will do so in the following ways:


  • Create a list of the things which the generator requires to power
  • Please note the start and run wattage of the respective items
  • Calculate minimum KVA or KW power specifications


How to Find Start and Run Wattage: It is important to measure the exact power requirements by finding the correct start and run wattage of the devices that you are preparing to power. You will usually find these for each unit, machine, appliance, or other electrical equipment concerned in the identification plate or the owner’s manual in the buyer’s kit.


Ampere-Watt Conversion: Sometimes you can consider the power specifications of the devices set out in amperes. Follow these equations to convert a device’s power demand from ampere to watts or you can use our handy conversion tool on our power calculator website as well.


For resistive load: Wattage = volts x amperes

For reactive charging: wattage = (amperes x volts) x charging factor


Power Requirement Charting: Sometimes you lose the owner’s manual or can not locate for whatever reason the power requirement specification of the equipment and/or other electrical devices that you are using. Below is a sample power consumption chart that shows some of the usual wattages used by specific devices and equipment. The chart is simply given as an example to illustrate how different wattages start and run, and how particular consumption specifications are set for each unit.


Different ways of calculating: There are a few different ways of calculating power requirements depending on the type and number of devices and how the generator is scheduled to be used:


  • Single operating motor
  • Multiple motors working at a time
  • No Electric Engines


Advantages of selecting the right generator size: Now that you have an understanding of how to select the right generator size to meet your needs, here are only a few of the benefits obtained through the process.:


  • No unexpected device outages
  • No shutdowns because of overloading power
  • Enhanced engine durability
  • Quality Garantie
  • Smoother care without any concerns
  • Increased life span of device
  • Personal safety assured
  • Far less risk of harm to the properties


Where to Buy & Position of Dealers and/or Service Providers: Since you’re not only purchasing a significant company commodity, but more certainly an item you’ll need to rely on for prime or emergency electrical power at some stage, perhaps in a crisis, to decide where to purchase is also a crucial factor that should not be overlooked. Seller experience, whether they are a full-service dealer or a small contract broker, and so on, all play a role.

Having spent over a quarter of a century with the brand, here are only a few of the reasons why you should always consider Generator Source as your first stop for all your industrial power generation needs:


  • 30 + Years of practice in business
  • Multi-port full duty workshop
  • Highly qualified mechanics and top Diesel engineers in the industry
  • High-end check and de-installation equipment
  • Helpful desk assistance and know-how in the workplace
  • We put all our goods to the test
  • Ever at a competitive price!


As this article indicates, there are clearly several factors that need to be taken into account when choosing the right generator for the job.

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