Yes. The cut must be oriented so that the flux passes through the armature when it is placed on the growler.
If you have to ask this there may be quite a few important things which you didn't know to ask.
Magnetic flux density and saturation come to mind. When you are cutting pieces out of the transformer core reflect; Would the designer have been willing to pay for the expense of the material which I am removing if he didn't have to? (Times a great number of units.)
A tip; run the transformer at half the rated voltage after you have raped the magnetic circuit. You may be able to reduce the saturation.
Bill
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"Why not the best?"
Jimmy Carter
I guess if we had all of the answers forums like this would not exist. I am not an electrical engineer hence the question. Remaining questions I have are:
1. could I use a variac to control the voltage
2. Is there any chance of changing the polarity of the device. I have heard people talking about changing positive ground devices like generators.
I guess since I am not messing with the fields I should not worry about it. How do you flash a generator, connect it like a motor?
1. This transformer has the secondaries wound around the primaries, should I apply the voltage to the primaries or the secondaries which are closer to the armateur.
2. Should I use a current limiter like a light bulb in series with the a/c line. I have seen some plans from the 1930's where they use a model T ignition coil with points as a current limiter, they put 32vdc on it and the points would open if there was a problem.
Flash: Momentary connection from battery to armature terminal. This sets the residual magnetism in the field in the proper orientation.
connect a Variac to power the normal line voltage winding of the transformer. The first time, use a voltmeter and an ammeter in the circuit. At the applied voltage reaches the saturation point the current will increase alarmingly. Stay about 15% below this voltage. Model T coil?? I would think that this would be inapplicable to a growler but I have been wrong before. You may get an answer to this from someone who is very old.
Bill
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"Why not the best?"
Jimmy Carter
caution in using a variac to load up the growler if the armature under test is not in place, the variac current rating does not apply at large step down settings
15% would blow a 15a fuse I believe. I was thinking of only putting a few amps into the growler. I guess at 60vac that would only be 9 amps. As far as flashing, wouldnt connecting it to the car and turning it on do the same thing?
If there is enough residual magnetism to generate, connecting it and starting the engine will polarize the generator. If the polarity is correct, it will work normally. If the residual polarity is incorrect, the generator will generate the wrong polarity. When the voltage rises enough to close the cut-out contacts the the generator will be connected to the battery and a very high current will result. If the battery has sufficient capacity to overcome the generator output the reverse current will re-polarize the generator correctly. Many technicians try to avoid this much drama.
If there is not enough residual magnetism the generator will not build up voltage.
Bill
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"Why not the best?"
Jimmy Carter
Well, my project is a failure. After cutting the leg of the transformer out, I connected the primary to a variac and ran it up with the armateur in place. Nothing happened, no noise or anything. just sat there dead. I ran it up to 120vac. Should I apply voltage to the secondaries or put DC to the tranny?
Do you know how to use a growler? Was current flowing through the xfrmr winding? What was the rated voltage of the winding to which you applied 120 Volts?
When I first read your post the attachment wasn't coming through. Now it is. Is that an actual cut or did you photoshop the second picture?
Bill
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"Why not the best?"
Jimmy Carter
With that core configuration there is still a low reluctance path through the limb which is not cut. Very little flux will cross the air gap because it is easier to follow the path in iron.
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If we learn from our mistakes I'm getting a great education!
First, yes a photoshop pic of my idea.
Second, scotty are you saying also cut the other leg of the transformer
Problem was its blowing the 10a fuse in the variac, I can only apply 20vac. Would the growler only work if an armature is in place or could a chunk of steel be a substitute?
How would you test a motor on a growler that does not have separations on the outer shell of the armature. I have seen some starter motors that are like that. see pic
Have you tried checking in place? Apply an alternating voltage to the field. Rotate the armature with a voltmeter connected to the brushes. Voltage should be zero or close to it. A varying voltage on the brushes indicates a bad winding. Same principle as a growler.
Bill
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"Why not the best?"
Jimmy Carter
With a power generator we use 120 Volts, 60 Hz.
For an automotive generator a much lower voltage will be appropriate. You will have to do your own testing to find out.
Use a multi-meter, connect it to the brushes.
Bill
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"Why not the best?"
Jimmy Carter
