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Diesel Generator for Sale – Weighing up the Options

With the chronic unreliability of Eskom power showing little sign of improving in the short to medium term, the necessity of providing alternative backup power is self-evident for most companies. The fact that the decision to invest in a backup diesel generator is made obligatory by Eskom’s inadequacy makes the procurement of a suitable unit very much a grudge purchase.

With this in mind, one needs to understand what options are open to a company that is obliged to spend money on a diesel generator to offset the loss of revenue and disruption of business they experience when the grid supply fails. Diesel generators (gensets) are currently the best solution for grid backup, especially for larger uses of power, because they are rapidly deployable, and compared to most renewable energy solutions, diesel gensets come at more reasonable capital cost.

They do, however, have higher running and maintenance costs. Once the decision is made to purchase a diesel generator, a number of questions need to be asked before searching the internet for “diesel generators for sale”. Does one purchase a new or used machine? Is a more expensive European or American generator a must or can one go with a Chinese-manufactured unit, which will typically be considerably less expensive than its Western-made counterpart?

After the above questions have been answered, the choice of which supplier of these units should be approached to provide the required solution can be tackled.

Buying a New Diesel Generator

Buying a brand new diesel generator is obviously, in most instances, going to be the approach with the least potential risk. Engaging with a reputable company offering diesel generators for sale not only means that a reliable unit will be provided but also that these companies will offer valuable expert advice with regard to the sizing, specification, and installation of the generator. They will also provide backup and spares for their products. Many industrial operations rely on large electric motors to run various processes.

These motors typically use up to six times their rated run capacity for a short duration when they start up. Taking this into account in isolation may result in the oversizing of a generator. Calculating the size generator required for a specific application is far more complex than many people give credit for. For example, harmonics may be caused by variable frequency drives used to facilitate smooth motor start-up.

This may be made worse by the sequential starting of motors in the plant. New generators can be specified and supplied with permanent magnet or auxiliary windings to provide generators with up to three times their nominal current to cover inrush peaks.

Advanced options, such as digital automatic voltage regulators (D-AVRs) are available for diesel gensets. These voltage controllers allow the generator to be sized for the run loads and not the start-up peak.

Smart control of the generator voltage also allows for improved efficiency and lower fuel consumption. This will also reduce maintenance costs and increase generator lifespan. Most diesel generators run best at around 75% of maximum capacity. Running a unit at very low load levels, which is typically what happens when the generator is oversized, is inefficient and may even damage the engine. There are many suppliers of diesel gensets and the choice of which company to use will come down to several considerations.

Price will be one of the considerations but is, by no means, the only one. Track record, reputation, brands offered, and the portfolio of successful installs will all help to make the purchasing decision. Buying a diesel generator is a capital-intensive, long-term investment, so it pays to choose wisely. Generator brands that dominate the premium sector of the market include Cummins, Volvo Penta, Perkins, Mitsubishi, and Caterpillar among others. More cost-effective solutions are on offer from Chinese manufacturers, such as FAW (FAWDE).

Diesel Generators for Sale – the Used Option

Commercial and industrial size diesel gensets are not cheap. Pair that with the fact that the provision of backup power is typically a “grudge purchase” and it is easy to see why many businesses consider purchasing a used unit to keep the cost as low as possible. One has to be careful not to be “penny wise and pound foolish” when electing to purchase a used machine.

While it is possible to find a barely used diesel generator at an attractive price more often than not, it is likely that the bargain price is for a machine that requires extensive maintenance, or even worse, is at the end of its life. Many diesel generators for sale are on offer because the cost of repairs and maintenance is approaching the cost of purchasing a new unit. Good used equipment can be found but one really needs to understand diesel gensets and exercise caution before making a purchase.

Never purchase used equipment that has no warranty backup. If the original manufacturer warranty still covers the unit, verify that the warranty can be transferred to you following the sale. Certain repairs or maintenance can be extremely costly and obliterate any saving made on purchasing a used unit.

Common sense considerations that apply to purchasing a used unit include being able to verify exactly how many hours the unit has already run. This is sometimes not easy to ascertain. Has your “bargain” unit been used every day for the past five years or has it barely run for a few hours? The application the generator was used for will give a strong indication of its probable run life.

Was it used for the ongoing generation of electric power i.e. prime/continuous power, or was it a standby machine? A generator used as a standby or backup power source will usually be better maintained and have much less wear than one used as a prime power source. Maintenance log books, while useful, do not always tell who carried out the maintenance and to what standard the work was done. A visual inspection will tell you a lot about a diesel generator.

A generator, like any mechanical device, suffers wear and tear during operation. Look for wear or fatigue and check the mechanical parts for cracks or corrosion. If the age and usage information are not available and the unit looks to be worn and corroded, it is often best to look for something else.

The generator manufacturer’s history and reputation are important when choosing to rely on used equipment. Unknown brands equate with significant risk. A trusted manufacturer with a reputation for producing equipment that can stand the test of time and that you know you can find parts and service for is a far better bet than a brand you have never of.