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Because the voltage is fixed (within allowable limits) whereas the current varies according to load.
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∙ 11y ago
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How do you connect and test exciter voltage?
To start the ac motor at starting by exciter.
Theory for load test on dc shunt generator?
load test on dc shunt generator is a test to plot the internal and external characteristics of the generator.
How do you do a megger test on a current transformer?
The megger test on a generator is usually done to check the insulation factor of a generator. The high voltage is usually used to test the insulation system of a the generator in question. It is recommended to do this test after every six months.
Can you test the output amps of a DC generator with no load?
Any voltage source, whether a generator or a battery, will NOT supply an output current unless it is connected to a load. So the only way to test the output current is by connecting it to a load.
Why is it required to vary the field current in only one direction while performing the open circuit test on dc generator?
rectification to the negative voltage
How do you test both water pumps on a 1949 ford 239 ci and test generator?
Wow! A flathead Ford V8. If you can drive the car, call around to your local parts stores and see if they can check a 6 volts generator. Here are some things to do if no one can test it for you. If you have a voltmeter, here are some easy tests to make: Measure the voltage across the battery. Should be about 6.3 volts with the engine off. As the engine speeds up, the voltage should increase to somewhere around 7 volts. If it does, the generator is working and charging the battery. If the voltmeter does not go up with the engine running, first check to see that the generator brushes are not worn excessively. If you can, apply a little pressure to the brushes while the engine is running and see if the gen light goes out or the voltmeter reading increases. If it does, the brushes may be worn to the point that they don't exert enough pressure on the commutator. If the brushes check OK, do this test: Disconnect the generator from the regulator (probably easiest to simply take the wires off the generator). Connect a jumper from DF on the generator to the generator frame. Now run the engine and measure the voltage from ground to D+ on the generator. NOTE: Some generators have different types of terminals; verify which is DF and which is D+. As you increase the engine speed, the voltage should jump up to +17 volts or so (@3000 RPM). If it passes this test, the generator is good. (Don't run this test longer than necessary as it will overheat the generator.) If it fails that test, the generator may need to be polarized. Leave the jumper wire connected from DF to ground. Remove the fan belt. Connect a wire from the battery + terminal to D+ on the generator. The generator shaft should start to spin. Don't run this way for more than a few seconds to avoid overheating. The generator will now be properly polarized. If the generator did not spin during this motoring test, the generator is likely defective. Put the belt back on and re-test for generator voltage with DF grounded. If the output voltage is still low, the generator is defective. About polarizing Generators, unlike alternators need to be "polarized". Auto generators need some magnetism to get started. This "residual" magnetism remains in the Field pole pieces even after the engine has stopped. The next time the generator starts up, the residual magnetism creates a small voltage in the Armature windings. Not enough to charge the battery, but enough to allow the Field windings to draw current. As the Field current increases, the pole pieces create even more magnetism. That makes even more voltage in the Armature, and the cycle continues until the generator is capable of producing maximum output. A generator which has been stored a long time or is freshly built may have lost the residual magnetism to the point where it can no longer get the generator started producing voltage. In the case of a new generator or one which has been mis-treated, the residual may even be of the wrong direction (North and South poles reversed). Polarization is a simple process used to restore the Field pole residual magnetism and ensure the magnetic direction is correct. As to you water pumps, remove the radiator cap and start the engine. Look for flow. No flow then both pumps are bad. If a pump is leaking at the shaft or through the weep hole, it needs rebuilding or replacement. The only sure fire way to know if the pump is good is to remove it and take a look inside. If the impeller is not broken, it should pump. Good luck, you have a classic.
Short Circuit test of a Synchronous Generator?
synchronous generator
Can a generator be a motor?
Usually, yes! You will need some kind of variable/low voltage supply (recommended either of those 2) and slowly turn up the voltage. If you notice it moving, then it will work. If it just buzzes and sits there, immediately cut off the voltage so you don't burn out your generator. Be careful, the maximum input voltage of it isn't usually measured since it's a generator, so while still on the variable supply, test and see when the brushes start to throw some decent sparks, at that point you should stop and whatever voltage that was should be your maximum after you subtract 8 volts or so.
Can you use megger as a generator?
In effect a hand crank megger is a generator. It generates a DC voltage that is used to test insulation conditions, by applying a higher that normal insulation value voltage to the material under test. +++ My apologies if my addition has already been published, for it's by no means clear what Answers actually does with amendments - as far as I can see here it rejected my first attempt which was more-or-less as follows: Yes, a 'Megger' (actually its trade-mark) contains a d.c. generator but I would not recommend using it as such, for it's designed to create a high voltage at very low current, so trying to use it as a power source may simply ruin it.
How do you test the 11KV HT cables?
The test equipment used to test high voltage cables is a hi-pot test where a high DC voltage is a applied to the cable. This voltage can be from 150% to 200% of the working voltage of the cable.See related links below.
Why open circuit test is performed on low voltage side?
generally open circuit test is performed on the low voltage side.....not on high voltage side.... becuase on low voltage side, we can apply that low voltage very easily ( i.e with a less amount of source is required)... whereas on high voltage side, we need a large power source in order to apply full voltage... in short circuit test, we will test on high voltage side by keeping Low voltage side being short circuit.because high voltage side needs less current source than low voltage side....
How do you calculate transformer voltage ratio test?
Secondary voltage / primary voltage
