Diesel Generators - New & Used Generators For Sale
Quality diesel generators you can rely on by FW Power. With over 60 diesel generators in stock, we can put your power in place right away. Please browse our website to find the following:
Used Diesel Generators – each one undergoes a 75-point service check and full load test, so you can rely on them for years to come.
New Diesel Generators – our vast range covers world class manufacturers and includes engines such as Perkins, Cummins, Doosan, Volvo and Baudouin.
Service & Maintenance – we offer several service plans to fulfill your needs and service throughout the UK.
FAQ’s – covers the most popular questions is a single place such as how often should a diesel generator be serviced? What is the difference between prime and standby power? How noisy is a diesel generator? And many more.
Continue reading for more of our services and some useful information on how a diesel generator works…
What is a Diesel Generator?
A diesel generator uses a diesel engine to provide mechanical power and convert it to electrical power using an alternator (electric generator). The engine rotates at 1500 rpm and this gives an output of 50Hz of electrical energy due to the number of poles and winding type within the alternator. Typical voltages are 380 – 415V for 3 phase generators and 220-240V for single phase generators. 60Hz systems used in the USA and parts of Asia rotate at 1800 rpm and have different output voltage from the alternator.
Three phase systems consists of an alternating current (AC) per phase that is of the same voltage and frequency amplitude but is out of phase by 120 degrees as shown in the diagram below:
Generator uses & key considerations:
The diesel generator (also known as a genset) can be used to provide electrical power where the power grid (mains) is not available which is known as prime power or continuous power if the load is constant. A standby generator provides emergency power when the power grid fails. Generators can also be used to top up the power grid which is known as peak lopping. Diesel generators and/or gas generators can be used to provide electrical power directly into the grid and offer grid support. Whichever method is used the generator must viewed as a power source in its own right and careful consideration given to breaker control / integration and earthing arrangements. Generally the generator should have a neutral earth bond to prevent steady state earth faults from occurring but this is not always the case particulary with respect to specialist marine applications and grid export. For applications with multiple generators then switched neutral isolators are often used.
What does FW Power offer?
FW Power offer generators for all applications and have specially designed control systems to suit each application. With our range of Deep Sea control panels most generators can be run as either prime power or standby power applications and can link into an Automatic Transfer Switch (Changeover Panel) to ensure a smooth and safe transition from the mains to the generator and vice versa. For critical applications where no loss of power can exist upon the transfer then UPS systems (Uninteruptable Power Supply) can be used to provide a no break transfer and return.
What are the main components of a Diesel Generator?
The main components of a generator are a diesel engine, generator ( electrical alternator), control panel, circuit breaker, steel base frame, fuel tank, sound attenuated canopy ( silent generators only), silencers, jacket water heater and a battery charger.
What is the difference between 3 Phase and Single Phase generators?
Generators are either 3 phase or single phase. In a 3 phase generator there are 3 live power cables (L1,L2 & L3) a neutral and an earth. For single phase there is only one live power cable (L1) a neutral and an earth. Three phase systems often have voltages quoted as 415/240V – in other words the voltage between phases (e.g. L1 & L2) is 415V and the voltage between a phase and neutral is 240V. Since in single phase systems there is only one power cable or phase then a phase to phase voltage does not exist and instead there is only a phase to neutral voltage of for example 240V.
Three phase systems are often used to power industrial premises that require large motors or pumps since the current carrying capacity to number of copper conductors is greater than that possible with single phase systems. Single phase systems are used for light duty industrial or domestic applications where the total current carrying capacity is less and it is thus more economical to have a single phase installation.
In a fully balanced e phase system the current flowing across each phase is the same and the neutral, which completes the circuit has no current flowing through it. When loads are un-balanced then the “difference” flows down the neutral. This is the reason that neutral cables should be the same size as the live power cables. There is an exception to this known as 3rd harmonics but that is beyond the basic descriptions given here. Since a current will always try to find its way back to its source then in an unbalanced load the current in the neutral does flow to earth in a neutral – earth bonded generator.
What is the difference between prime power and standby power?
The maximum power available for a varying electrical load for unlimited hours. A 10% overload is available for 1 hour in 12.
Restrictions are often placed upon the average value of the varying load, typically 70% of the prime power and also on the overload operation which typically is for a maximum of 25 hours per year.
Where the load is not variable such as exporting to the Grid then the Prime Power definition is not used and Continuous Operation Power (COP) is used. If the number of hours at a non variable load are limited and not as high as COP then sometimes the rating of Limited Time Running (LTP) is used in place of COP.
The maximum power available with a varying load for the duration of the interruption of the normal source power. No overload is available with a Standby rating.
Restrictions are generally placed upon the average load, typically 70% of the Standby Ratings and hours limitations are imposed of usually 500 hours per year but sometimes 200 hours per year.
A typical example of Standby Power maybe a warehouse distribution centre that has its own mains supply but cannot afford to lose power in the event of a mains outage. Hospitals. Railway stations, airports, control centres, data centres, hotels and certain farming environments all follow the same principles. Ultra critical installations such as hospitals, airports and data centres will often have a UPS system integrated into the design as well as a standby generator to the standby generator !!
Prime power will be used where there is no mains supply into a building or where the mains supply is not of adequate capacity to power large industrial equipment and the generator is sued to power the shortfall.
A practical example of Prime and Standby Power ratings:
A generator rated at 300 kVA Prime Power and 330 kVA Standby Power.
When used for Prime Power the generator can run at 300 kVA but the average load should be 70% of this rating i.e. 210 kVA. The number of annual run hours are not limited. For every 1 hour in 12 (subject to the manufacturers guidelines on hours limitations) the generator can run at a 10% overload giving 330 kVA.
When used for Standby Power the generator can run at 330 kVA but the average load should be 70% of this rating i.e. 231 kVA. There is no overload available for Standby Power and the manufacturers restrictions on run hours should be taken into account.
What are the differences to consider between Prime and Standby Generators?
Prime Powered Generators are run on a regular basis. As such fuel supply and maintenance are absolutely critical. Most generators have a base fuel tank which is designed for short run periods of typically 6-10 hours, so an externally connected fuel tank will be required to run the generator for longer periods. These tanks vary from 500 litres to upwards of 20,000L depending upon how long you wish to run the generator. Please view the FW Power Guide on Generator Fuel Consumption.
Maintenance intervals on most generators are 500 hours although they can be as low as 250 hours for certain engines. Thinking about maintenance at an early stage of the project and having a plan in mind can save both downtime and considerable expense in the future. Access to and around the generator is critical. Please view the FW Power Guide on Generator Maintenance.
Standby Generators are designed to run when the main provider of power – usually the Grid – fails. In order to transition the power from the failed supply to the generator a Transfer Switch is required. Ensuring that the generator interfaces with the transfer switch is critical and may require the installation and programming of a number of signal cables e.g. auto start signal, up to speed signal. Please view the FW Power Guide to Automatic Transfer Switches.
Fuel supply is also a consideration for Standby applications and the question should be asked – how long do I want my generator to run for in the event of an extended power failure? The answer to this question is often dependent upon how critical the supply is for either the integrity of your business e.g. a data centre or hospital or what level of financial disruption is caused by not having a generator running.
Because a Standby Generator is not run regularly to provide the main power it must be ran up periodically by the maintenance team to ensure that it starts and supplies the building load when required. A Standby Generator should be fitted with a trickle charge battery charger to keep the starting batteries ready for action and it is also advisable to fit a jacket water heater which keeps the engine at a pre-set temperature and significantly aids in cold starting, reduced engine wear and reduced smoking from the engine when cold.
We have not covered the sizing of your generator within this summary but please view the FW Power Guide to Generator Sizing and Installation for more information.
FW Power – The Home of Diesel Generators
GENERATOR SALES – NEW AND USED.
New & used Diesel Generators ranging from 10 kVA up to 2900 kVA. Working with leading brands to ensure a reliable power source. Each used generator undergoes our thorough 75 point service inspection & load bank test.
AUTOMATIC TRANSFER SWITCHES – NEW AND USED.
FW Power will be able to guide and advise what size ATS you need for your application. With new or used available, our ATS’s will ensure a smooth transition from mains to generator power and back again.
GENERATOR INSTALLATION & COMMISSIONING.
Our skilled generator engineers are on hand to install and commission any sized diesel generator. We have experience on a wide variety of complex installations.
SERVICE AND MAINTENANCE CONTRACTS.
FW Power service and maintain both prime power and standby generators across the UK. We have our own fleet of load banks and a fully stocked parts warehouse. We offer many different packages and can tailor them to suit your needs.
Offered to our contracted customers we offer a direct number to one of our experienced engineers who can normally get you up and running over the phone until a full repair can be undertaken.
Further Reading & References:
Frequently asked questions about diesel generators by FW Power:
Generator knowledge centre by FW Power:
New Diesel Generators by FW Power:
Used Diesel Generators by FW Power:
Grounding of AC generators and switching the neutral in emergency and standby power systems by Cummins Power Generation:
The importance of grounding standby generator systems by MTU onsite energy:
Diesel Generators on Wikepedia:
Diesel Generators by Science Direct: