Low power factor in dg sets – Part 1

The state of power supply has been erratic for a long time and many areas in the country are still struggling for a reliable source of electricity. Especially the industries that need uninterrupted power supply for economic sustainability have shown a tremendous rise in moving to diesel generators as an important source of electricity and not just a temporary arrangement. With the increase in usage and desirability of diesel generators the need to find ways to improve their efficiency and power factor (PF) is also on the rise.

What are the causes of low power factor?

Different load sizes that come with different power factor effects is the primary cause for the overall reduction in the power factor of an electrical layout. But various other reasons contribute to power factor output being low and in a significant way. The reasons are primarily connected to the fundamental limitations of a power generator.

A diesel power generator is a source of power that doesn’t have a network of sources and loads to load it. Thus, it has a limited capacity to fulfill sudden and large demands of reactive power. To build more on this limitation, the below can be associated as reasons why there is lower power factor in dg sets:

1.      Over sized dg sets

Designers of a plant usually tend to oversize a dg set or limit its loading owing to a largely existent myth that 0.8 is the ‘designed’ PF for dg sets. This essentially leads to liberally sized diesel guzzlers that do not deliver the full version of their economic capability. The alternator of a dg set is same as its larger variants connected to utility power turbines with scaled down proportions. Which means that it by design has the capability to deliver the exact amount rated as its KVA (kilovolt-ampere). So, 0.8 is not a design variable but it’s more like a thumb rule inferred from the average power factor in any industrial electrical layout with a general set of inductive - PF values .8 to .85, non-linear – Power Factor values .5 to .65 and linear (unity PF) - 0.80.

2.      Phase loading that’s unbalanced

Most of the industrial electrical layouts have loads that are liberally connected on various power phase lines because physical limitations of the process layouts are simpler to visualize when compared to the electrical balancing on every line. This doesn’t seem to be a problem when it comes to the grid connected situation where the primary connection of a phase maintains the sync in the remaining from the utility side owing to a grid’s macro effect. But in the case of a dg set that’s’ captive, syncing the phases is not even a function built into its power electronics.

3.      The load of compensation

From various reports on the effect of different power factors on dg sets and detecting safe zones it has become evident that close to unity Power Factor is achievable and safer but low Power Factor for greater periods has more negative impact.

This is part one of a two-part series. In the second part, learn how to correct dg sets with low Power Factor.

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Parts of a diesel generator and their functions.

We all know that a diesel generator is used as a source of backup when supply of power is not constant. They have assumed great importance and have almost become a necessity for households and companies in areas where there is a shortage of electrical supply. Given the promising nature of a diesel generator, we all have at some point used it or at least have known its merits. But have we ever tried to understand what are the various parts that power the diesel generator and help it function?

Let us look at some of the main components of a diesel generator and their functions:

1.       Engine – The heart of the system

The function of the engine is to create the mechanical energy that the diesel generator converts into electricity. The design of the engine is aimed at generating a maximum supply of electrical current by running on diesel or other alternate fuels.

2.       A comprehensive fuel system

Generators that run on diesel or any other fuel, have a fuel system that stores and pumps it to the engine. The tank stores a good amount of fuel to power the generator for several hours at a stretch. A fuel pipe in the system connects the tank to the engine while a return pipe connects the engine to the fuel tank for the return of fuel. A fuel pump moves fuel from the tank through fuel pipe and to the engine. There is a fuel filter which filters out debris from the fuel, if any before delivering it to the engine. A fuel injector atomizes and injects the fuel directly into the combustion chamber of the engine.

3.       An alternator

The alternator in a diesel generator converts mechanical energy produced by the engine into electrical current. It comprises of the stator and the rotor (or armature). The stator is stationary and contains a set of coils that conduct electricity. The rotor moves to create a constantly rotating electromagnetic field around the stator.

4.       Voltage Regulator

The alternator may generate electrical voltage but the level of voltage needs to be regulated that is suitable for practical use. Voltage regulator is an electrical regulator that maintains a constant level of voltage.

5.       Impeccable cooling and exhaust systems

The temperature of a diesel generator must be regulated to prevent overheating while being used. Generators can use a fan, coolant or both to control the temperature of the generator at work. The internal combustion engines are usually cooled by passing engine coolant through the engine block. The generator also produces exhaust as the combustion chamber converts fuel. There are exhaust systems that dispel harmful gases emitted.

6.       Lubrication system

A diesel generator comprises of various moving parts. These parts need to be oiled for their smooth functioning. The lubrication system ensures that the parts are well oiled and functioning at their best.

7.       Acoustic Enclosure

Being a mechanical product with many moving parts, a diesel engine makes lot of noise during its operation. In order to control the noise emission, the engine and alternator assembly is housed in a soundproof canopy having sound absorbent material from inside. As per Central Pollution Control Board (CPCB), the maximum noise emission from a generator should not exceed 75 dBA from 1 m distance from the canopy.

For more information about diesel generators, please visit: http://www.mahindrapowerol.com/  or

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QUICK HACKS TO SAVE ENERGY

Even though electricity is a luxury in various regions of India, it is often taken for granted by people who reside in towns and metropolitan cities. So much so that some months your electricity usage, as apparent from your bills, makes you break out into a cold sweat. Also, with summers around, power usage will soar more than ever.

It is high time that we as responsible citizens do our bit to save some energy so that the rest of the country can benefit from it. Shared below are quick hacks to save energy:

AC can be best set at an optimum temperature of 24 degrees 

We all know that AC’s suck up a major chunk of electricity hence to save energy and for optimum results, try setting up your AC at 24 degrees and not lower than that.

Appliances should be switched off when not in use

You must know that any electrical appliance when left unattended and is in standby mode still consumes electricity. In fact, devices on standby suck up a whopping 5% of the total electricity consumption. This is a serious reason to switch off all your appliances when not in use. Mobile phone chargers when left plugged in with switches still on tend to still consume power. So, do remember to turn the switch off.

The right kind of lights can help save a lot of energy

The variety of lights you choose to use can be the most effective way to save on power. The right kind of lights can make all the difference in the amount of electricity you consume. Compact-sized fluorescent bulbs may offer almost the same amount of light and brightness as in the case of incandescent bulbs. But the fact remains that they are 4 times more energy efficient. So, while these bulbs are more expensive than the regular ones, they do use much less energy and last relatively longer. In certain cases, they may last for as long as a year.

Use your iron wisely

Whether you believe it or no, here’s telling you that your iron can contribute to your energy-saving pursuit. In case you’re about to buy an iron, ensure buying one which has an automatic temperature cut-off. Do not wet your clothes before you iron them, this will ensure low power consumption.

Keep your fridge organized always

When you have a crowded fridge, there is less room for the air to efficiently circulate. With that, your fridge starts working harder to keep cool. The harder it works; the more electricity it consumes. On the other hand, the more organised your freezer, the better it works. The thermostat of your fridge should always be in the medium cooling position. Do not put in hot or warm foods straightaway. The liquids must always be covered and food must be wrapped up so that they do not moisten which can cause the compressor to work extra hard.

Pay attention to your washing machine

When you fill up your washing machine to the brim with soiled clothes, and use the right amount of detergent, it works most efficiently. That said, do not overload the machine leading it to cope harder and using up more power. Cold water may be optimally utilized when the clothes are not too dirty. Dry out your clothes naturally, make use of a timer facility if need be. When you make use of cooler and less water you end up saving about 80% to 85% of the energy utilized in washing clothes. 

Give that electrical dryer a miss unless you absolutely cannot

For tropical monsoon climates, there may be no other option than using electric dryers from time to time. Dryers consume electricity enormously. If you must absolutely use one, dry your clothes in consecutive loads.

Opt for an Eco-friendly shower

Your shower could be an energy-friendly one when you switch the geyser off after 10 minutes of it running. In case you cannot do without hot water, decrease the thermostat, setting it to 50 degrees. If you can, do use a solar water heater. This is a much Eco-friendlier alternative to a regular water heater.

Use a microwave to cook whenever you can 

Microwaves consume half as much energy as a regular electric stove. You never need to preheat a microwave unless if you want to bake. Also, if you must check on your food, refrain from doing it ever so often. Every time you open the door of your microwave the temperature drops by 25 degrees and will need to consume a lot more energy to pick up back again. 

A pressure cooker saves electricity too

Whenever you can, make use of a pressure cooker to cook. It will save you time as well as energy. Let any items that you got out from the fridge to settle to room temperature by leaving it outside for at least 10 minutes, and only then cook them.

Create shaded spaces around your house

Potted plants don’t just look pleasing, but they can also serve to be amazing energy-savers. You may line them up outside of your house. This will keep the sun from shining straight onto your AC. An air conditioning unit that operates in a shaded space needs up to 100% less electricity than one exposed to the sun.

Hope these hacks will prove to be helpful to you in saving electricity.

Mahindra Powerol’s range of energy-efficient diesel generators can come to your rescue during the melting summers. For information please visit: http://www.mahindrapowerol.com/

A Close Look at Wet Stacking of Diesel Generators – Effects, Prevention and Solution

Diesel as a source of fuel is conveniently independent and its compression ignition systems have a higher thermal efficiency than that of gas engines that use the spark ignition systems. That said, an important factor to be considered when choosing a diesel generator is its potential for ‘wet stacking’. Diesel generator designers must bring into account the potential for wet stacking when they determine the equipment for the system, maintenance, service programs and load calculations. Further, this post will discuss the adverse effects of wet stacking on your diesel generator and methods you can use to eliminate the condition.

What is wet stacking?

Just like all internal combustion engines, a generator must have exactly the right amount of air-to-fuel ratio to operate at its best efficiency and deliver optimum results. It should be able to utilize its designed operational temperature so that the fuel can burn out completely. Diesel generators rely on the hot compressed air in the cylinder to ignite the fuel. Because the air is cooler than the design temperature, the conditions for combustion are not ideal. Thus, the fuel ignites, but it doesn’t burn completely. The unburned fuel exhausts and results into wetness in the exhaust system. Hence, the phrase, wet stacking.

How do you know if your generator is wet stacking?

Your diesel generator may likely be performing inefficiently if one or all the below conditions exist:-

• There’s a continuous release of black exhaust smoke from your diesel generator’s exhaust pipe.
• A thick, dark substance is continually dripping from the exhaust pipes.
• There’s a formation of deposits of soot or hard carbons.

Effects wet stacking has on your generator

• Raised expenses: Wet stacking can shorten the life of the engine of your diesel generator by many years and you may have to replace it much before than you planned to.

• Air pollution: The level of smoke emissions produced due to wet stacking is restricted in many urban areas.

• Low power: The deposits caused due to wet stacking will reduce the maximum power of your diesel generator even before the engine is damaged.

• Higher maintenance: A diesel generator that is experiencing wet stacking will need considerably higher maintenance than one which is adequately loaded.

Prevention and Solution:

The basic solution for wet stacking is a few hours of operation at a load of about 75% of the generator’s nameplate rating (or more) to raise the exhaust temperature high enough so that the unburned fuel in the exhaust system can be vaporized and the soot can be blown out away. At the same time, the exhaust temperature at that load is higher than the auto-ignition temperature for diesel which on rare occasions can ignite fuel and soot within the exhaust system. In case a unit has a history of extended operation at low load, or if there’s no proof that it’s been exercised recently at adequate load, it’s vital to get a professional generator maintenance report to manage the load testing procedure. If a generator is made to prolong operations at low loads, it can lead to permanent damage of the engine which will need a major engine overhaul. The costs of an overhaul can run high and so, replacing the unit altogether is the more economical option.

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Rating your diesel generator right.

Ratings for a diesel generator is result of intended use and the ability to supply power. So, when you look at buying a generator, you would first consider its intended use. While it may seem obvious what power rating is required for an application but there are a number of factors to consider before purchasing a generator. Let’s familiarize ourselves with generator ratings and their relevance.

Standby Power Rating

The primary application of a Standby Power Rated generator is to supply emergency power for a limited duration during a power outage. These generators do not have an overload capability built into the units. Standby power rating should be applied to the unit where public utility power is available and power cuts are very rare.

Prime Power Rating

The prime power rating is the maximum power accessible at the variable load for an unlimited number of hours per year in a variable load setting. Prime power rated generators should be used if the public utility power is intermittent with frequent power cuts.

Continuous Power Rating

Continuous power rating is used in applications where the need for supplying power is at a constant 100% load for an unlimited number of hours each year. These units are used in applications where the power grid is unreachable, for e.g.: mining, agriculture or military operations.

Elevations and Temperature’s Effect on Power Rating

Beyond the above mentioned considerations, elevation and temperature are also factors to be considered before rating the engine.

For more information on diesel generators and the various kVA’s visit www.mahindrapowerol.com