Redrock

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  • Publicado : 30 de septiembre de 2010
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OPERATING 60 CYCLE INDUCTION MOTORS AS GENERATORS any motor can be used as a generator and any generator will motor under the proper Circumstances. The purpose of this paper is to describe the connections required to convert the two most common types of induction motors into AC generators. The two types of motors most readily Converted are three phase Squirrel cage Induction motors and capacitorstart single-phase induction motors. Although the connections are different, both types of machines exhibit similar operating characteristics. Below is an outline form applying to either type of generator? The instruction, for connecting the machines and small parts that you will need are discussed later. STEP 1- Electricaly connect the unit as outlined under the connection section. STEP 2-Connect the machine by belt or other suitable means to a Source of mechanical power such as a gasoline engine. Turn the machine at about its nameplate speed. Most machines will be either about 1800 RPM or about 3600 RPM. STEP 3- With no loads of any kind connected to the generator, its voltage should build-up (usually a faint generator hum is audible). If you are using a Single-phase machine, be sure itis turning the same direction that it turned as a motor. Build up can be checked by momentarily connecting a light bulb across the output terminals to check for power. STEP 4- Reduce generator Speed until the machine will just keep the light bulb lit. You will find below this Speed, the generator will simply stop generating. STEP 5- with the generator Operating at minimum speed where it continuedto generate, connect a light bulb load to the average load for the generator. If you have been using a smaller load to test for generator build-up, it may be necessary to increase the Speed a bit to maintain generating mode. STEP 6- set the generator speed by checking the generators output voltage. The faster you turn the generator the higher its voltage will become, etc. If a voltmeter is notavailable, a simple method is to compare the brightness of two bulbs of the same type, one plugged into the generator and the other plugged into the wall. The speed is about right when the bulbs are equally bright. RATING- your generator can be rated at 500 watts per motor horse- power, This is a comfortable rating and allows for some short time 0verload capacity. When selecting the loads for thegenerator remember that most electric motors require six to ten times their rated power when starting. As an example, a 1/3HP-freezer motor may require up to 3 HP worth of generating capacity to start it. High Speed portable tool motors are the main exception. These Series wound motors usually start quite successfully at 2 or 3 times their rated power current at rated voltage) level, Motor loads arebest estimated by multiplying their nameplate volts times nameplate amps. This product is really V\ but can be used safely as watts for the purpose of generator rating. Your generator will produce sine wave power generally at a frequency slightly below 60 HZ. An electric clock with a second hand will read the exact frequency in seconds in one minute. CAUTIONSI- You are generating lethal voltages-use appropriate care. 2- The generator will not build-up its voltage when loaded. It must always be started with no load connected. 3- Running the generator at speeds higher than the nameplate rating may generate very high voltages and cause the capacitors to explode or the machine to flash over inside and catch fire. Speeds in excess or 4000 RPM may even cause the rotor to fly apart inside themachine.

4- DonÕt leave the generator unattended until it has run about 2 hours without overheating. A safe motor temperature is when you can barely hold your hand on the generator for 5- 10 seconds and no hot or oily smell is coming from the machine. Faults or dead shorts may be placed on the generator without harm since it will simply stop generating. TROUBLE SHOOTING- If the generator will...
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