| DEWALT Generators DG7000 7000 Watt Gas Portable Electric Generator |
| DEWALT Generators DG6000E 6000 Watt Generator with Electric Start |
| In electricity generation, an electrical generator is a device that converts kinetic energy to electrical energy, generally using electromagnetic induction. The reverse conversion of electrical energy into mechanical energy is done by a motor, and motors and generators have many similarities. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, or any other source of mechanical energy. An engine-generator is the combination of an electrical generator and an engine (prime mover) mounted together to form a single piece of equipment. This combination is also called an engine-generator set or a gen-set. In many contexts, the engine is taken for granted and the combined unit is simply called a generator. In addition to the engine and generator, engine-generators generally include a fuel tank, an engine speed regulator and a generator voltage regulator, cooling and exhaust systems, and lubrication system. Units larger than about 1 kW rating have a battery and electric starter; very large units may start with compressed air. Standby power generating units often include an automatic starting system and a transfer switch to disconnect the load from the utility power source and connect it to the generator. Engine-generators are used to supply electrical power in places where utility (central station) power is not available, or where power is needed only temporarily. Small generators are sometimes used to supply power tools at construction sites. Trailer-mounted generators supply power for temporary installations of lighting, sound amplification systems, amusement rides etc. Standby power generators are permanently installed and kept ready to supply power to critical loads during temporary interruptions of the utility power supply. Hospitals, communications service installations, data processing centers, sewage pumping stations and many other important facilities are equipped with standby power generators. Privately-owned generators are especially popular in countries where grid power is undependable or unavailable. Trailer-mounted generators can be towed to disaster areas where grid power has been temporarily disrupted. The generator voltage (volts), frequency (Hz) and power (watts) ratings are selected to suit the load that will be connected. Engine-generators are available in a wide range of power ratings. These include small, hand-portable units that can supply several hundred watts of power, hand-cart mounted units, as pictured above, that can supply several thousand watts and stationary or trailer-mounted units that can supply over a million watts. The smaller units tend to use gasoline (petrol) as a fuel, and the larger ones have various fuel types, including diesel, natural gas and propane (liquid or gas). The engine can also operate on diesel and gas simultaneously (bi-fuel operation). There are only a few portable three-phase generator models available in the US. Most of the portable units available are single phase power only and most of the three-phase generators manufactured are large industrial type generators. Portable engine-generators may require an external power conditioner to safely operate some types of electronic equipment. Small portable generators may use an inverter. Inverter models can run at slower RPMs to generate the power that is necessary, thus reducing the noise of the engine and making it more fuel-efficient. Inverter generators are best to power sensitive electronic devices such as computers and lights that use a ballast. BY Gary Nave A portable generator is just what the name implies. It is for portable and non-permanent, stationary, installed applications. Portables do not have a forced air cooling system that changes air within a compartment. It releases its combustion heat and exhaust to the ambient air, which simply means that you cant build it into a room or generator house without auxiliary air and exhaust handling equipment.A stationary unit has a forced air or other type of cooling system that allows it to be enclosed, most typically in an outside weather housing mounted on a concrete pad similar to a central air conditioning unit. A portable generator does not have an engine controller, which automatically replicates all the actions you subconsciously perform when starting your car. Engine controllers allow for remote control via a simple on-off switch or automatically with an automatic transfer switch (ATS). Stationary generators also have more extensive protection and safety shutdown features than do portables. Portable generators all operate at the faster 3600-RPM speed where more engine power is produced allowing for a smaller engine, which is a benefit in reducing weight. Most stationary units use larger engines running at a slower 1800-RPM speed to achieve the same power result, but with much quieter and smoother operation. Its kind of the same thing as the difference between your lawnmower and your car at a fast idle. Dont try to cut corners by not getting a generator with enough power. The cost per watt (the unit of electrical power) goes down considerably as the size of the generator goes up. Many people create problems of all sorts by buying small. Only resistive loads like lights and heaters can be added directly to calculate load requirements. Others-like motors-require extra power of several magnitudes to start than they use to run. Most people have little comprehension of how much power they use in normal living or how much various loads consume. If youre thinking of upgrading your generated power, remember that anything that makes heat with electricity (electric heat, water heaters, dryers, etc.) uses large amounts of power compared to other loads. If your house heats with electricity, consider another heat source or be prepared to buy a large generator. Motors that start under light load (well and septic pumps, many fans) require two to three times the power to start than they do to run while those starting under heavy loads (refrigerators, compressors) may take as much as five times to start. A "rule of thumb": Allow 2-3 KW of generator power per horsepower of electric motor. |
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