In part 5 we look at Making the right generator choices!
Modern generators are often turbocharged, smaller, less expensive, more efficient than older models, and capable of supplying up to 100% load within only a few seconds. A wide choice of fuel is available.
Diesel generators are the most commonly installed. The fuel is usually chosen for its low flammability and stability over time. Also, when considering capital expenditure, diesel-powered products are usually the most cost effective route that is taken.
Natural gas is a regularly used alternative where available, although the engine will be needed to be larger than a diesel equivalent to compensate for the lower calorific value of gas compared with petrol or diesel. An advantage of installing a natural gas generator is that it will not require a fuel tank. The runtime will not be a problem since the fuel will be coming from the gas main.
The disadvantages are that if a gas main of sufficient size is not already in place, laying one could be expensive; also, should the mains gas supply be interrupted, the situation is beyond your control.
A 100kVA generator will weigh approximately 1.7 metric tonnes. This is before the weight of the fuel is added. The size of the fuel tank can vary depending on application and need, but a good weight approximation is to allow one kilo per litre of diesel to keep on the safe side.
The installation position is, therefore, important. If the chosen site is at ground level, for instance, the car park, weight is not a problem. If however the installation site is within a building, or on the roof, the load bearing capabilities of the structure will need to be followed strictly.
If considering installing either within the building or on the roof, the problem of refuelling should also be taken into consideration.
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All internal combustion engines produce carbon monoxide (CO) emissions and noise. Exhaust gases will have to be vented, and best practice is for this exhaust pipe to be of less than 10 meters in length. The exit point should be away from windows and other air intake points.
Noise can be attenuated to an acceptable level for use outdoors by the use of acoustic hoods and to a lesser degree, weather-proof enclosures. Catalytic converters can be installed within the silencers of diesel generators. This will help to reduce both chemical and noise pollution. Because these converters themselves operate between 200º C to 300º C, they themselves will have to be thermally insulated.
Diesel generators are usually air cooled; because of this, it may be necessary to install forced cooling and ventilation within the generator’s immediate environment.
Remote monitoring services are a valuable maintenance option. The service provides constant monitoring while the generator is in operation and monitors your weekly auto-start procedures. It automatically confirms successful test runs, provides notification of any mains failure, common alarms and low fuel levels. You are notified of any alerts by SMS text or email as required.