Diesel Generators an Overview

Diesel generators are ideal for industrial applications and are often found as the backup power system of choice for healthcare facilities, data centers, mining and agricultural operations and greenhouse facilities.

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Why are Diesel Generators so Popular?

As a fuel, diesel is preferred by many because of its lower cost and ability to extend the life of the generator itself. Also, diesel fuel may contain specific additives which stabilize it, creating a longer shelf life for those certain applications where your backup unit may not be used for long periods of time.

These units are rugged and reliable and an economic choice for many commercial applications, as both permanent standby systems and also portable power sources at construction sites.


The majority of these generators run at 1800RPM and are water-cooled, which gives them a longer life span than portable gas generators which are air-cooled and have the standard 3600 RPM.  Diesel units are so dependable that, generally speaking, you can get up to 30,000 hours of use before servicing is required provided the machine has been properly maintained.

Cost Efficient

As fuel prices continue to climb, diesel generators become an even more attractive option. Typically speaking, diesel costs per KW produced are usually 30-50% less than natural gas, gasoline or propane. And, as mentioned earlier, the longer lifespan and more hours of use mean maintenance costs tend to be lower as well.

Determining Size

Although diesel units typically range in size from 20KW up to 2000 KW, they can come as small as 6 KW and go as large as 3000 KW. The larger models are available as towable units which are mounted on trailers and can be towed to construction sites. In order to determine the size of generator you require, look at your peak load over the last 24 months.

How Diesel Engines Work

What is the main difference between a diesel engine and a gasoline engine, and how does a diesel generator provide all that power with less fuel consumption?

Gas engines produce electricity by taking in a mixture of air and gas which is then compressed and ignited with a spark. A diesel engine, on the other hand, takes in only air and compresses it first, then injects fuel into that compressed air. The heat of the compressed air lights the fuel without the need of any spark.

The diesel engine has a higher compression ration – 14:1 and even as high as 25:1 compared to gasoline’s ratio of 8:1 or 12:1. This higher compression ratio is what makes the diesel generator more efficient.

Buying Guide

There are four main types of diesel units available on the market today: Portable generators, stand-by units, towable and power take-off generators. Each type will come with a different power output and price, so it’s important to make sure you know exactly what application you’ll be using it for and determine what your budget is first.


Portable generators are smaller and usually cost less than other models. They are extremely useful when it comes to providing temporary power at job sites or remote locations. These units are also good for home use when there is a power failure due to inclement weather. They can be operated virtually anywhere out of doors because their fuel tanks are built right in. Never run a portable unit indoors as they produce toxic fumes.


Unlike the portable model, a standby unit can be installed permanently and used as an alternative source of power during an emergency. These models are commonly seen at hospitals and nursing homes and data centers and are typically hardwired to the building’s electrical system. In order to prevent any damage to your existing wiring and other electrical equipment, it is best to have your standby generator professionally installed by a qualified electrician.

Also, it’s important to make sure you purchase a reliable standby machine. A quality unit will shut down automatically if it loses oil pressure or overheats. Other things to look for are a solid metal enclosure, noise-reduction mufflers and emissions regulations.

When researching diesel generators to buy, it’s a good idea to keep certain things in mind, like the reliability and reputation of the manufacturer, the model you require, terms of the warranty, price and what, if any, maintenance will be provided after the sale.

Why Consider a Used Diesel Generator?

Buying a used industrial diesel generator can be very beneficial. Many companies, both large and small, invest in pre-owned or low-hour used units because it is usually the most cost-effective way of acquiring high-quality assets and equipment at low prices.

Having said this, there are some factors to take into account when purchasing a used generator:

  • How well was the machine maintained?
  • Does it come with a full service history?
  • What are the age, hours and usage?
  • What is the physical condition (wear and tear) of the machine?
  • How does it perform in a load test?
  • Does it come with any kid of warranty or guarantee?
  • Will you purchase from a broker or distributor?

Installation Overview

A diesel genset consists of the engine, the generator, the base, control systems circuit breakers, sound attenuation, canopy, water heaters and a starting system. In order for all of these to work properly, your generator set must be installed correctly.

There are a few basic guidelines for the installation of diesel standby generators but most will come with their own set of instructions, so always refer to these before you start.

Your first priority will be to choose a location for your installation. Things to keep in mind when selecting your location are ventilation methods, humidity, access to the unit, exhaust piping and temperature.

Although it is highly recommended that your diesel generator be installed and serviced by an experienced and certified technician who will follow all codes and regulations, it is still good for you to understand and follow the basic installation procedures:

Before the unit is installed, there should be a thorough inspection to see if any damage has occurred during the shipping process.

Your generator should be located outdoors in a protective enclosure where proper ventilation is available.  Make sure your unit is placed on a level surface and a bit above ground so as to protect the machine from rising water levels during certain seasons.

In an effort to minimize the amount of cables and piping, install your generator as close to the transfer switch and fuel supply as you can.

Usually, grounding lugs are provided for grounding the frame and external conducting parts of your machine. Make sure that these grounding procedures meet all of your local regulations and are followed strictly.

Before inserting any batteries into your generator make certain they are all fully charged.

The transfer switch is a delicate piece of equipment and should be handled with care, especially when unpacking. It must be wall-mounted and all points level with each other.

The generator should be connected to your electrical system only through the transfer switch.

When wiring, make sure all critical loads are grouped together but wired separately into the exclusive distribution panel.

If you’re ready to start shopping for a used diesel generator, take a look at our selection and feel free to give us a call if you don’t see what you need in our inventory. We work with a nationwide network of reputable dealers and can locate your ideal unit for you.