Spares and Parts
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WHAT IS A GENERATOR?
A generating set is the combination of an engine, alternator, control system and circuit breakers in most cases mounted on a base. There is a huge array of additional items which are often fitted to a generator or in some cases come as standard. Often a fuel tank is integrated into the design as well as the possibility of sound attenuated canopies.
1. Sound attenuation has become a large part of the generating set industry in recent times as the advantages have been noted. The canopy can protect the generating set from the elements, it can dampen the noise produced by the engine when noise is a factor, such as in a built up area.
2. Jacket water heaters are often also fitted to generating sets to allow them to remain warm for when they are needed. By keeping the engine block warm, the generator is able to start up and produce power quicker as it will not have to warm up from cold temperatures.
3. Some other extras often fitted include Automatic Transfer Switches (ATS), Automatic Mains Failure Panel (AMF), Remote administration systems through GSM or 3G networks depending on the level of access and information required.
Generators range in size and application. Small generators can be used for camping and be as small as a briefcase, to generators the size of a small house to run a shopping centre or mine. It all depends on the application that the generating set is needed for. In general an average home will use a generator between the sizes of 5 kVA and 40 kVA depending on the size of the home and what the user would like to run on the generator.
Generators can either be for prime power or standby power. In a prime power scenario the application for which the generator is needed does not have any power currently. The generator is being installed for the sole purpose of providing power to the application on a continuous basis. A standby generator is installed along side another power source as an emergency backup. If the mains power or the prime power generator fails, the standby generator will start and provide power for a short period of time. A standby generating set can be smaller than that of a prime power generator because it is used for less time when needed. Hence a standby power generator is rated at 10% above that of the prime power generator. The standby generator can run at this additional 10% for a period of up to 1 hour safely, whilst the generator will continue to run after this period, it is the industry standard to only run at the additional 10% for an hour at a time.
In general, generators will run at 1500 RPM, but it is possible to get a generator which runs at 3000 RPM or higher. Generators which run at a higher RPM than 1500 should only be used as standby generating sets, operating up to 8 hours a day. The reason for this is that the increased RPM for extended periods places strain on all the components of the engine, this can cause the generator to fail after not having run for very long as the heat and strain endured by the higher RPM will quickly erode the integrity of the components of the generator causing engine problems.
Like a motor vehicle, a generator needs to be serviced. Because an engine has numerous moving parts they need to be maintained in a good condition to allow the generator to run as it should. If the generator is not serviced regularly the owner runs the risk of the generator having irreparable harm caused to either the engine or the alternator. A simple analogy for why and how often your generator should be service is this: A diesel car running at 1500 RPM in 5th gear at 100 Km/h for 100 Hours covers a distance of 10 000km. Hence if a generator has run for 100 Hours at 1500 RPM, it essentially has covered 10 000km, the standard distance for a car service.
Control systems play a large role in the operation of the generator. The control system can be an array of gauges, relays and switches as was common a few years ago, or it can be a digital display as has become the industry standard in recent times. The control panel allows the user to monitor the generator as a whole. The engine performance can be monitored to ensure that it is running at an optimal level, as well as having sensors on the engine to allow the control system to shut the generator down should there be a problem (Such as low oil pressure). The control panel also allows the user to monitor the voltage and amperage input and output allowing the generator to react to under and over voltage problems on an incoming power supply. The complexity and functionality of a generator control panel varies between manufacturers, but most include the above mentioned. Additional items can be integrated into a control panel to allow them to be remotely monitored and controlled, again depending on the manufacturer of the control panel.
The alternator is the component which produces the power. The engine runs and turns the alternator which produces power. A rotating magnet, often referred to as the rotor turns within the static conductors often referred to as the stator. The conductor is comprised of wound coils on an iron core. The magnetic field cuts across the conductors generating the current. Most often there are three sets of stator windings which produce three phase power.
In general generator sets run on diesel fuel. But you do get generators which run on petrol and gas. Very large generators tend to run on gas due to the cost associated with the fuel consumption, whilst small generators run on petrol.
An aspect often over looked by potential buyers is the actual build quality of the generating set. The amalgamation of the various individual parts into a working generator can be achieved easily, but for a good quality generator to be manufactured takes a little more research and development. From the strength of the steel used to make the base to ensure it doesn’t bend when being transported to the engine mountings, every aspect is important and over looking any of these aspects could result in you receiving a “lemon” generator. When looking at a generator set for any application it is advisable to ensure that the quality of the product is good, that service is available and that spares can be obtained easily.