Generator sets are designed to operate under substantial load. This may seem unimportant, but loading a generator set properly is essential to healthy engine operation and long engine life. The ideal operation targets of each generator set will depend on the application and rating. Generally speaking, standby – rated diesel generator sets are designed to operate between 50 and 85 percent load, while continuous – rated diesel generator sets are optimized between 70 and 100 percent load.

Operating a diesel generator set at load levels less than 30 percent of rated output for extended time periods impacts the set negatively. The most prevalent consequence is engine exhaust slobber, which is also known as exhaust manifold slobber or wet stacking. Engine slobber is a black, oily liquid that can leak from exhaust manifold joints due to extended low or no-load scenarios.

Within the engine, soot can cause internal glazing of the cylinder bores, sticking of the piston rings, reducing compression and the injectors are likely to have a build-up of carbon causing more un-burnt fuel to pass through the combustion chamber into the exhaust.

The first sign of this problem is heavy smoke from the exhaust, eventually; the un-burnt fuel will condense in the exhaust and mix with the soot, to create a thick dark liquid that looks like engine oil. This liquid will seep from the exhaust, and will appear to be an oil leak. This liquid can build up in the exhaust silencer and there is the risk of it igniting from the increased heat of the exhaust fumes, if the generator is subsequently put under full load.

These conditions can lead to power losses, poor performance and accelerated wear of components, which can cause increased maintenance costs and unplanned downtime or failure. If a generator continues to be operated with no load or very light load there is a possibility that permanent engine damage can occur.

To help minimize the effects of under loading, it is critical to have proper load estimation, operation and maintenance plans in place to maintain the health and reliability of the complete system and your generator set.

If you need assistance in this regard, contact John Holt Engineering, the trusted name in diesel generators.

How Does a Diesel Generator Create Electricity?

Generators are useful appliances that supply electrical power during a power outage and prevent discontinuity of daily activities or disruption of business operations. Generators are available in different electrical and physical configurations for use in different applications. They are designed to operate on variety of fuels such as diesel, gasoline, propane or natural gas and have no connection to POWER GRID.

How does a generator work?

An electric generator is a device that converts mechanical energy obtained from an external source (prime mover) into electrical energy as the output.

The diesel generator is the combination of two components, a diesel engine with an electric or electromagnetic generator (often an alternator) working together to generate electrical energy. This is specific case of engine – generator (alternator). These two components are connected by a crankshaft. When diesel engine burns the diesel fuel in order to produce motion for the generator, the crankshaft transfers the motion produced by the diesel engine to the magnets (within a chamber containing electromagnets) of the generator assembly. A generator works through the principle of electromagnetic induction. This high speed motion causes an electric current to be produced.

It is important to understand that a generator does not actually ‘create’ electrical energy. Instead, it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit. This flow of electric charges constitutes the output electric current supplied by the generator. This mechanism can be understood by considering the generator to be analogous to a water pump, which causes the flow of water but does not actually ‘create’ the water flowing through it.

The modern-day generator works on the principle of electromagnetic induction discovered by Michael Faraday in 1831-32. Faraday discovered that the above flow of electric charges could be induced by moving an electrical conductor, such as a wire that contains electric charges, in a magnetic field. This movement creates a voltage difference between the two ends of the wire or electrical conductor, which in turn causes the electric charges to flow, thus generating electric current.

Main components of a generator

The main components of a diesel generator can be broadly classified as follows (refer to illustration below):

  1. Engine
  2. Alternator
  3. Panel
  4. Cooling System
  5. Diesel Tank/Base Frame

If you require more information on your diesel generator or you want to procure one, please contact John Holt Engineering.





How Does Refrigerant Help Your Air Conditioner?

Refrigerant is a compound typically found in either a fluid or gaseous state. It readily absorbs heat from the environment and can provide refrigeration or air conditioning when combined with other components such as compressors and evaporators. If you have heard about the R22 refrigerant phase out in favour of R410A refrigerant, you might be especially interested to know more about how refrigerant works and what part it plays in cooling your home.

How Refrigerant Works

Without refrigerant, there would be no air conditioning, refrigeration or freezing technology.

Air conditioners contain refrigerant inside copper coils. As refrigerant absorbs heat from indoor air, it transitions from a low-pressure gas to a high-pressure liquid. Air conditioning components send the refrigerant outside where a fan blows hot air over the coils and exhausts it to the exterior.

The refrigerant then cools down and turns back into a low-pressure gas. Another fan located inside the home blows air over the cool coils to distribute the resulting cold air throughout the building. Then the cycle repeats.

Types of Refrigerants

The most common refrigerants used for air conditioning over the years include:

  • Chlorofluorocarbons (CFCs), including R12: This is known to contribute to the depletion of the ozone layers of the atmosphere which is not only harmful to the surface of the earth but destructive to human beings as well. Production of new stocks ceased in 1994.
  • Hydro chlorofluorocarbons (HCFCs), including R22: Slightly less damaging to the ozone than R12, but the Environmental Protection Agency EPA has mandated a phase out as a result of the damaging effect it has on the environment and human.
  • Hydro fluorocarbons (HFCs), including R410A and R134: With no chlorine in the mix, this is safer for the environment and is now being used in place of R22. Air conditioners that run on R410A are more efficient, offer better air quality, increase comfort and improve reliability.

Is it Time to Upgrade?

Go outside and take a look at the exterior component of your air conditioner. If it says R22 on the side, you’re cooling your home with an outdated, environmentally hazardous refrigerant.

You can’t simply replace R22 with R410A because system parts aren’t compatible. This means the next time your aging air conditioner requires maintenance and/or servicing – especially a refrigerant-related one – it’s probably time to upgrade to a unit that runs on R410A. While this requires an investment, the resulting increased efficiency, better air quality, increased comfort and improved reliability are worth it, and no harm to the environment.

When you’re ready to explore upgrading to an R410A air conditioner, please contact John Holt Cooling. We offer accurate sizing and extended warranty plans for the best upgrade experience possible.

Yes, we provide cooling solution that aligns with green environment.


Safety against Fire is a very important thing at work places as well as at homes. Every year large numbers of people die due to Fire. Fire safety can easily be ensured by having Fire Fighting Equipment and proper Fire Protection. The Importance of Fire fighting Equipment is an indispensable one to ensure maximum Protection against Fire. The Fire Fighting Equipment also ensures safety of the Fire Fighters who risk their lives to save others.

Some Major Fire Fighting Equipment Are:

  • Fire Extinguisher – Fire Extinguisher is the primary need of any small or big establishment. Every house should have sufficient numbers of Fire Extinguishers to ensure Fire safety. There are different types of Fire Extinguishers available in the market for different types of Fire.

Fire for Linkedin 2

  • Fire Alarms – This is the first and most important thing to have a full proof Fire Protection System. The Fire Alarms alert in cases of Fire and the loud Fire Alarm leads one to the exact place where there has been the Fire.
  • Fire fighting Blankets – Fire fighting Blankets are really helpful in preventing the fire from spreading. The large Fire fighting Blankets cover the fire and cut off the oxygen supply and result in reducing or extinguishing the Fire.
  • Fire Sprinklers – The moment there is a Fire Alarm the Fire Sprinklers start releasing and raining water with a constant pressure and force. It is a known fact that Fire Sprinklers have effectively prevented major Fires in many cases.
  • Fire Hose – Fire Hose is a major necessity for fighting major Fires. Fire Hose is a hose having high pressure and is made to carry water or a Fire retardant like foam to extinguish Fire. This is a Fire Equipment that every building should have.

Fire Hose

  • Fire Fighting Truck – describes any vehicle that has been customised for use during fire fighting operations. These vehicles are highly customised depending on their needs and the duty they will be performing. These duties can include fire fighting, vehicle extrication, dangerous goods investigations, rescue, medical, swift water rescue and plane crashes.

Fire for Linkedin

If you need assistance in this regard, contact John Holt Fire & Safety Solutions, the trusted name in fire and safety services.


Diesel generator sets – used for either prime or backup (emergency) power – must be regularly maintained to ensure they provide quality power throughout their service life. Companies/individuals who either use generators for prime power or back up, may establish maintenance contracts with generator dealers to maintain their gensets. The life-cycle of power generators is well established and documented making routine maintenance fairly straight forward. Best generator maintenance practice is following the maintenance schedule provided by the manufacturer of the generator.

The long outstanding use of generators over time has provided the necessary knowledge to predict when certain components will fail or be in need of service. A fairly reliable maintenance schedule can usually be acquired from the manufacturer and can be employed by a local generator dealer with experience in power generation. Adhering to this schedule will ensure maximum service time for the generator and proper operation when it is called upon to provide power.

The main responsibilities of the maintenance contractors would be to inspect systems, study the technical data provided by the manufacturers, maintain records and take precautionary measures for safety as suggested by the manufacturers.

Some of the steps taken to ensure smooth generator operation while carrying out scheduled maintenance include:

  • Timely removal of worn out parts or upgrading the components
  • Checking fluid levels
  • Battery inspection and cleaning of connections
  • Verifying control panel readings and indicators
  • Changing fuel and air filters

Small investments made in replacing components and maintaining generators on a regular basis can save expensive and unnecessary upgrades or even replacement of the entire genset in the future.


When performing routine maintenance, each action taken should be logged, and the readings and various parameters are recorded along with the date of inspection and hour meter reading of the generator. These set of readings are compared with the next set of data collected. Any absurd variation of readings indicates faulty performance of the unit.

Other factors to be checked periodically are starting and timing relays, start signal continuity, and utility phase sensing.

Preventative maintenance thus ensures that you get uninterrupted power supply for all your needs. You are assured of service on priority basis in case of dire emergency and discounted service rate for additional support or work. Once a business enters into such contracts, the facility can relax on this aspect as the maintenance provider keeps track of when the next servicing is due and makes the visits in regular intervals. They ensure that the products purchased through them receive consistent and reliable service.