External to the building – this is usually the most straightforward installation and totally enclosed weatherproof housings can be both cost effective and environmentally friendly. Local authorities often need to be consulted to check acoustic noise restrictions in the area, in particular residential locations need to be carefully considered. Exhaust emissions are also critical near buildings and may need special treatment. If considering a roof top installation, weight and vibration also need to be carefully checked by specialists. Self-contained sets have the added benefit of being easily moved to new locations if necessary.

How do you want the set to work? – Local manual, remote or automatic
Manual start – a simple electric pushbutton or keyswitch is often used for short term hire sets or for installations where the site is permanently manned and the load can suffer a break in supply.

Remote start – the set can be started by a remote signal from a manual changeover device.

Automatically – usually referred to as AMF, auto start upon mains failure, the set receives a signal from a remote sensing device or phase failure relay usually located in an automatic changeover panel that switches from mains to generator either by interlocked Contactors, Moulded case circuit breakers or Air circuit breakers depending upon the rating of the set. The return to mains can be automatic or manual depending upon the site requirements. With automatic starting there is always a brief delay of several seconds whilst the engine gets up to speed and ready to accept the load. (If this is unacceptable for certain types of load it is necessary to install a UPS to ‘bridge this gap’ and ensure a seamless transition of power)

How do you cool the generator?
Fan cooled radiators are the most common form of engine cooling; the fans are either engine driven or electrically powered. Flexible couplings usually provide the link to either a sound attenuated louvre or ductwork that ensures that hot air is correctly discharged from the enclosure or plantroom. Occasionally remote mounted radiators are employed in difficult plantroom installations where ductwork is not a suitable option.

How do you get rid of exhaust gases?
For plantroom installations, it is normal to simply discharge the exhaust to atmosphere alongside the hot air discharge louver, however, this is not always acceptable due to site limitations or local legislation and it is often necessary to route the discharge gases through a flue pipe either fixed to an external building wall or through an internal riser. Both options need careful planning to keep back pressure to a minimum, typically by reducing the number of bends and increasing the pipe diameter. External pipework can be installed using in stainless steel for a more durable finish although painted mild steel is often acceptable in view of the cost differential.

Enclosed sets generally employ an internal silencer system consisting of primary and secondary mufflers with the gases routed out through the canopy via a weatherproof discharge point often known as a bird’s beak. Catalytic converters are becoming more common in an effort to reduce harmful emissions.

How to store fuel and re-fill the Generator
Most simple enclosed sets incorporate a double skinned or bunded base tank, built into the main base frame or skids of the set, these can usually provide adequate running time for standby applications, typically 8-20 hours. Longer run times or permanently running sets generally use a separate double skinned bulk fuel tank, with a fuel transfer system consisting of one or two pumps and a fuel fill point incorporating overfill alarm, high and low level detection and various other options such as leak detection, pipework insulation etc

What about the noise of the generator?
Engines will always create high levels of noise and the process of reducing this noise is achieved by using a combination of attenuators, silencers and acoustic enclosures. Audible noise levels are measured in decibels over a given distance; site conditions and local legislation usually dictates the level that can be tolerated. Enclosed sets are typically 75-80dBA at one metre, higher levels of attenuation can achieve 65dBA or even less, but the cost and physical size often becomes prohibitive.