The ultimate guide to diesel generator

1. The electrical power demand: this is the power demand expected from a generator in kW and kVA. Special loads as motors, UPS, helium lighting, electric furnaces or others should be mentioned.(1)Base load Power: Power available for continuous full load operation. An overload of 10% permitted for one hour in every twelve hours of operation.
   (2)Prime Power: Power available at variable load in lieu of main power network. An overload of 10% permitted for one hour in every twelve hours of operation.
   (3)Standby Power: Power available at a variable load in the event of a main power network failure up to a maximum of 500 hours per year. No overload is permitted.
2. Duty of operation: this is could be of three modes of operation:
3. Rated voltage. It depends on where you are located.
4. Rated frequency. It depends on where you are located.
5. Number of phases. It is either single phase (two wires) or three phase (four wires). It depends on equipment you have. You can check this info from your mains energy meter.
6. Manual Start or Auto Start. This info shows the engine response after failure of mains (national grid). Shall this be manually done through operators or automatically through an automatic transfer switch (ATS) linked to the Genset controller?
7. Site Conditions. This includes the max and min temperatures, altitude above sea level, relative humidity and dust.
8. Sound level. If Genset will be placed in residential areas, the sound of generator will be very noisy and should be proofed. Check our canopy section for more info.
9. Exhaust Emissions compliance. This depends on what type of emissions legislations are applied in your country. Check Perkins emissions guide.

Other Features

You can check our standard features through leaflets for Genset and control panels. If other features are requested, check the option section in control panel leaflet or contact our sales dept.

What is the cheapest way to maintain my generator and increase its lifetime?

Follow the recommendations of the preventive maintenance schedule and carry out a daily visual inspection.

The visual inspection should only take a few minutes. When time is taken to perform these checks, costly repairs and accidents can be avoided. For maximum engine service life, make a thorough inspection of the generating set compartment before starting the engine. Look for items such as oil leaks or coolant leaks, loose fastening, worn belts, loose connections and debris buildup.

Clean, repair or renew, as necessary. Refer to operation manuals and / or Assembly & Dismantling Manual and follow all relevant safety precautions. Always clean fluid leaks in accordance with local regulations to prevent contamination. For any type of leak (coolant, lubrication, or fuel oil) clean up the fluid.

If leakage is observed, find the source and correct the leak. If a leak is suspected, check the fluid levels more often than recommended until the leak is found or repaired.

Warning! Accumulated grease and / or oil on an engine or floor are a fire hazard. Remove any debris by steam cleaning or by using high pressure water.

1. All guards must be fitted in their correct places. Repair or renew damaged or missing guards.
2. Wipe all caps and plugs before the engine is serviced in order to reduce the chance of contamination.
3. Check the condition of all coolant pipes. Ensure that they are correctly installed, clamped and tight.
4. Inspect the coolant pump for coolant leaks. Note: The coolant pump seal is lubricated by coolant in the coolant system. It is normal for a small amount of leakage to occur as the engine cools down and parts contract. Excessive coolant leakage may indicate the need to renew the coolant pump seal.
5. Inspect the radiator and heater radiator (if fitted) for damaged, bent or broken fins, corrosion, dirt, grease, insects, leaves, oil and other debris.
6. Inspect the lubrication system for leaks at the front crankshaft seal, the rear crankshaft seal, the oil sump, the oil filters and the valve cover.
7. Inspect the fuel system for leaks. Look for loose or damaged fuel lines.
8. Drain the water and sediment from the fuel tanks and water/fuel separator filter on daily basis; ensure that only clean fuel enters the fuel system.
9. Inspect the air inlet system. Ensure ducts are clear of restriction. Look for elbow cracks and loose clamps. Check that hoses and tubes are not in contact with other hoses, tubes, wiring harnesses, etc.
10. Check that the Fan and accessory drive belts are fitted to the correct tension. Inspect the belts for cracks, breaks or other damage. Note: Where more than one belt is used between pulleys, it is important that all belts are renewed together.
11. Inspect all wires and wiring harnesses for loose connections. Make sure all electrical connections are clean and tight. Also look for worn or frayed wires and renew if necessary.
12. Check that all ground straps are in good condition. Ensure that the ground straps and joint faces are clean and tight.
13. Disconnect any battery charges which are not protected against the current drain of the starter motor.
14. Check the condition of the electrolyte level of the batteries, unless maintenance free batteries are fitted.
15. Ensure that the battery is at full charge and that all connections are clean and tight.
16. Check the condition of the Genset controller, gauges and meters on control panel. Renew those that are damaged, cracked or that cannot be calibrated.
17. Check the condition of the alternator air flow; blocked air-inlet or air-outlet. Also check the alternator cooling fan for any crack.
18. Check the condition of the anti-vibration mountings for any deterioration or non-tightened screws.
19. Check the condition of the circuit breaker and its box for any damage.
20. Check the condition of the power and control cables for any damage, short/open circuit or loose connections.

How can I get preventive maintenance schedule of my generator?

It should be attached with genset catalogs. Whatever the case,Feel free to contact our service department (lashari@damaan.com.pk)

When do I have to change the Air filters?

According to preventive maintenance schedule, it is recommended that the air filters must be changed every one year of operation. You can check the air cleaner service indicator connected to Filter housing to see if there is restriction in the air filter.

When do I have to change the lube oil and oil filters?

The time interval for changing the lube oil and oil filters is found in the maintenance schedule which may differ depending on engine type and sulfur content of fuel.

How can I have my generator ready to take load?

This is dependent on two main factors:

• Your commitment to preventive maintenance.
• The engine temperature must always be above 25C. If the engine is placed in a very cold environment, you may need to have engine heaters.

 Contact ourtechnical support people for details.

What is the minimum load that the engine must be operated?

The minimum Load that an engine must be operated must not be less than 25-30% of its rated output.

What is the risk if engine load is less than the minimum?

If an engine is operated on a load less than the minimum, certain symptoms of high Lubrication oil consumption and oil leaks may be observed. The cylinder temperatures are too low to insure complete burning of all the fuel delivered. A further result is that of abnormal carbon built up on the valves, piston crowns and exhaust ports. Thus the normal service interval of overhauls may be reduced.

What are the available types of Generator sets (Gensets)?

Gensets are mainly fitted with either diesel, gasoline or gas engines.

What are the most common definitions and deliverables that customers expect from a Genset?

They expect measurable power density, load acceptance, emissions, fuel consumption and noise. Power density measures the rating over the volume of the engine; the higher the power density is the more effective the Genset can be. Load Acceptance – Gensets are often used for standby/emergency power, where they will be expected to start-up, run up to running speed and then accept a large % of maximum electrical load.

Load acceptance is measured in terms of a % frequency dip and a recovery time, and is defined by ISO 8528-5 and NFPA 99/110. Additional requirements are customer driven demanding typically 80% of the prime rating within 10 seconds of start-up, within ISO 8528-5 limits. Engine load acceptance has been demonstrated as a linear function of trapped mass. 

	Generator Class
Frequency Criteria	G2	G3
Steady State Frequency Band (%)	1.5	0.5
Transient Deviation On Load Increase (%)	10.0	7.0
Transient Deviation On Load Decrease (%)	10.0	10.0
Recovery Time (s)	5	3
Steady State Tolerance Band	2.0	2.9

Emissions- Genset emissions are complicated and specific to the country in which they operate. Generally requirements are less demanding than other off highway equipment, but are often driven by marketing rather than legislative needs. Legislative limits are complicated, determined by introduction date, engine powers and power rating. The three most important limits are listed below with links to sites where full documentation can be found.

European Limits (Directive 97/98/EC)

Commonly referred to as EU Stage ‘X’ Emissions

www.dieselnet.com/standards/eu/offroad.html

North American Limits (Federal Regulations 40 CFR Part 89)

Commonly referred to as EPA Tier ‘X’ Emissions

www.dieselnet.com/standards/us/offroad.html

TA LUFT

Legislation	Power	NOx g/Nm3	SO2 g/Nm3	CO g/Nm3	PM g/Nm3	HC g/Nm3
TA Luft (1986)	< 3 MWth	4.0	-	0.65	0.13	0.15
	³ 3 MWth	2.0	-	0.65	0.13	0.15
½ TA Luft	< 3 MWth	2.0	-	0.65*	0.13	0.15
	³ 3 MWth	1.0	-	0.65*	0.13	0.15

* Sometimes 0.325 g/Nm3Perkins emissions brochure:

http://www.perkins.com/cda/components/securedFile/displaySecuredFileServletJSP?fileId=286181&languageId=7

Fuel Consumption- Each Genset should carry a specs sheet that details the fuel consumption levels according to load percentages and frequency. 

Noise Levels- Gensets could be sold either as open sets or coupled with sound proof canopies. Each type of canopy with specific design delivers a certain level of sound attenuation measured by dBa (Decibels).

What is a Genset and how does it differ to the industrial engine on which most are based?

The following list sets out to explain many of the basic terms applicable to Genset design, development and ownership.

Electrounit – A fixed speed diesel engine with ratings to suit a Genset application. Comes complete with radiator, cooling group and fan.

Electropak – An Electrounit without radiator, cooling group and fan. Suitable for individually installed Combined Heat & Power setups.

IOPU – Independent Operating Power Unit. These are multi speed non vehicle power units. They are normally sold with radiator, cooling group and fan, and typically share ratings from their off highway derivatives. Typical applications include pumps and compressors.

Operating Speed – Gen-sets are normally governed to fixed speed running. 1500 rpm to produce 50Hz electrical supply for European market and 1800 rpm to produce 60 Hz for US market. 60Hz supply can be achieved at 1200Hz with some alternator sets– this is uncommon.

KWe – Kilowatts electrical is a measure of electrical power produced by a Genset. 60Hz generator sets are usually marketed in terms of kWe.

KVa – Kilovolt amps is a measure of electrical power produced by a Genset. 50Hz Gensets are usually marketed in terms of kVa. As Gensets produce an alternating current P=VI doesn’t hold true. Voltage and current follow sinusoidal wave forms with a phase shift due to the reactance (generated by inductance & capacitance) of the load on the alternator, and hence a power factor is used. Industry assumes a 100% resistive load for which a 0.8 power factor is used. This relates kWe to kVa by the following:

kWe = kVa x 0.8

Marketing – As a general rule of thumb, a Genset will produce X kVa at 50Hz and X kWe at 60Hz. So we owe the confusing nomenclature to marketing who would like to sell, for example, a 100kVa (50Hz)/100kWe (60Hz) Genset.

Fuel Coolers – Gen-sets are normally fitted into a frame, which holds a small fuel or “day tank” for limited time running. If the Genset operates in elevated ambient temperatures, or the engine has a high fuel spill ratio, the temperature of the fuel will often be controlled by a small fuel cooler (air-to-fuel) mounted on the cooling group. The cooler prevents rises in “day tank” temperatures preventing fuel injector damage.

Fans – All Electrounits are fitted complete with fans to provide cooling to the radiator and charge cooler if fitted. Two versions of fans are normally offered for Gensets and IOPU’s, pushers (which blow air through the radiator) and pullers (which pull air through the radiator). The customer is able to specify the type most relevant to their application/installation. The type of fan used will affect the ambient air temperature the bulk of the engine will see, and may have consequences on the engines rating and performance.

Fan Power (Fp) – Depending on the size of the Genset, the power required to drive the fan will vary between 10% for smaller Gensets (<10L) and 5% for larger Gensets (>10L).

Alternator Efficiency (ha) – The alternator on the Genset converts the mechanical energy delivered by the engine into electrical energy, and has an associated efficiency. Typically alternators have an efficiency of 0.95 (95%).

kWm – Gen-sets are marketed in terms of the electrical power which they produce. However engine manufacturers are more interested in the mechanical power which their engine needs to deliver to the alternator to provide the quoted electrical power. This includes fan powers and alternator efficiency:

kWe = (kWm –Fp) x ha or kWe = kWm x 0.90 x 0.95 ( <10L engine)

kWe = (kWm –Fp) x ha or kWe = kWm x 0.95 x 0.95 (>10L engine)

Ambient/Altitude Clearance - Gen-sets are operated in global environments, with extreme ambient and altitude operating environments. Running at higher ambient temperatures adds additional loads on the cooling system, and at elevated altitudes the inlet system struggles to deliver sufficient air for combustion with the lower air density/pressure. Gen-sets are expected to run at altitudes up to 4000m and ambient temperatures of 55 ⁰C, which may require derate.

Clearance is defined as the margin on the altitude/ambient performance limiting parameters (such as coolant and exhaust temperature) when tested at standard operating conditions (sea level 25 ⁰C). From the Ambient/Altitude clearance, curves are developed to assist application engineers in sizing appropriate derate for extreme operating conditions.

Power Rating - Gen-sets are sold at three main power ratings determined by their application. Power ratings are defined by ISO 8528-1. Generic power ratings are summarised below:

Rating

Summary

Standby Power

Typically 100% of maximum permissible power.

100% load factor of published standby power.

No overload capability.

Maximum usage of 500 hours per year.

Maximum 300 hours continuous running.

Prime Power

Typically 91% of maximum permissible power.

Mean load factor of 80% published prime power

over 24hour period.

10 % overload for 1 hour in 10.

Unlimited running.

Baseload Power (Continuous)

Typically 70% of maximum permissible power.

100% load factor of published baseload power.

10 % overload for 1 hour in 10.

 Unlimited running.

Governing – Gen-sets are fixed speed applications with governors developed to maintain the desired running speed within careful limits. This is particularly important as electrical equipment powered by the Genset may be damaged by supply outside of the normal 50/60Hz limits. Gen-set governing is detailed by ISO 8528.