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(and how to avoid them)
With society increasingly reliant on electricity, interruptions in power supplies have the potential to cause chaos, impacting everything from our home lives to travel, business productivity to data integrity and, in more extreme cases, loss of life and damage to infrastructure. To mitigate this risk, having a backup power source is crucial. With a reputation for being robust and reliable, diesel generators provide an ideal solution, giving owners peace of mind that they will provide a reliable power source in the event of an outage. Yet, just like any other internal combustion engine, lubrication, cooling systems, fuel systems and electrics can develop faults. Paul Brickman from Crestchic Loadbanks explores some of the common reasons for generator failure.
One of the most common causes of generator problems is battery failure. In short, a failed battery won’t supply the current the generator needs to start. Battery problems can be caused by sulfation build up, which occurs when the lead sulfates in the electrolyte begin to coat the battery’s lead plates. As the sulfation builds on the plates, it inhibits the electrical conversion, preventing the battery from providing the current needed to start the generator.
Dirty and loose connections are the culprit for a host of battery problems, from a build-up of lead debris in the sedimentary trays to open cells caused by overcurrent or insufficient battery capacity. Preventative maintenance is key to overcoming these issues and overcoming potential failure before it occurs. Cleaning and tightening of cable connections and monitoring the charge rates on a regular basis will help to ensure that your backup generator works as expected in the event of a power outage.
It is also worth bearing in mind that battery failure can occur when the charger breaker is open or tripped. This is usually due to human error, when the charger has been switched off for maintenance. Ensure all testing and maintenance is carried out by a skilled professional who will follow the relevant steps and procedures to fully check a generator is working properly after maintenance or repairs.
Coolant levels and overheating
Low levels of coolant in the system cause overheating, leading to a whole host of other issues, from melted bearings, warped crankshafts and overheated cylinder heads through to damage to the radiator core, exhaust valves and valve guides.
Overheating can be caused by low coolant levels, which may indicate a leak somewhere in the system, commonly the block heater hoses. To prevent issues, hoses should be checked regularly for signs of wear, bulges and cracking; clamps should be tightened to reduce the likelihood of leaks; and coolant antifreeze and additives should be maintained to prevent pitting and engine damage. However, while checking the system and keeping an eye out for puddles of coolant is important, overheating can also be caused by a build-up of dirt and debris, a broken fan or fan belt, clogged injectors or air filters, or low oil levels.
The only way to accurately test a cooling system and ensure that the thermostats are fully open is to test the generator under load. Weekly running, while vital to the overall health of the system, simply won’t cause the thermostat to open enough to test the system – making loadbank testing the best way to mitigate any issues.
Leaks or “wet stacking”
Very often, problems that are perceived to be oil leaks are actually caused by “wet stacking”, where thick, dark liquid drips from the engine’s exhaust and turbo chargers. Wet stacking usually happens when engines operate significantly below their rated output level (recommended levels vary between manufacturers). This kind of excessive no-load run time causes a build-up of unburned fuel deposits around the combustion chamber, injector nozzles, piston rings, turbo charger and exhaust. This, combined with condensed water results in carbon particles and moisture gathering around the exhaust system.
The potential impact of wet-stacking includes reduced power, increased emissions and increased operational costs. When this happens, the engine can be cleaned up by running it at full load to burn off excess fuel, using a loadbank to place a load on the system. If the generator is used below the rated output level on a regular or consistent basis, consider pairing it with a load bank more permanently to keep it running at 70-80% of rated capacity and prevent a “wet stacking” from occurring. A load tracking loadbank is ideal for this application.
With emissions controls becoming increasingly stringent, the use of exhaust after-treatment systems is becoming more commonplace. These tend to require the engine to be running at an optimum load / temperature. If the generator does not have sufficient load the performance of the after-treatment could be compromised, in this instance a loadbank can be used to ensure sufficient load is provided to allow the generator to run at its optimal performance level.
The increased level of bio content in fuel can exacerbate stagnating fuel issues causing microbial build-up in the fuel. Ultimately, this build-up could result in the generator being unable to run when called upon. Polishing / cleaning the fuel removes harmful sediment such as water, sludge and microbial contamination through filtration and circulation
Some generators are equipped with an auto shutdown mechanism when the fuel reaches critical levels. Running out of fuel, or problems caused by fuel stagnating in the system, can be avoided by maintaining the fuel tanks and checking them for water and contaminants which can damage the system. By the same token, high fuel level alarms can be activated by natural thermal expansion of the fuel on a hot day.
Naturally, there are times when simple human error can cause the generator not to start up when needed. The most common issues relate to switches being left in the wrong position when weekly checks are made. Control switches, battery chargers, ground fault sensors and switchgear are often switched off as part of routine checks, making it important that these are checked and reset to prevent non-start situations, ideally by a trained and experienced technician.
The alternator is the part of the generator which converts the mechanical energy of the engine into electrical energy, making it vital to the effective performance of the system. Alternator housing, windings, bearings, controls and cooling system should all be included in your maintenance. A resistive-reactive loadbank test will help to identify any problems and test the alternator’s capability to provide the required voltage and pinpoint any work that needs to be done to prevent the failure of the generator.
The role of loadbank testing
The reality is often that those in charge of maintaining backup power have no regular testing schedule, making an assumption that occasionally powering the generator up, testing for a minimal period, or a visual inspection, will overcome any potential issues. By not testing the system adequately, the generator is put at risk of failure – with the fuel, exhaust and cooling system untested, along with the potential for embedded moisture, putting the system in the very high-risk category.
Using a loadbank overcomes this risk, by applying a load to the generator which imitates the operational or ‘real’ load that a generator would use in normal operational conditions. Properly planned and implemented, loadbanks can be used as part of a preventative maintenance strategy, minimising the likelihood of unscheduled breakdowns and outages and effectively negating the potential risk of downtime.
For more information on the role of load banks when managing and maintaining generators, please visit www.crestchicloadbanks.com
Common reasons for generator failure
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