HANG A WEIGHT ON ONE OF THE STUDS

HANG A WEIGHT ON ONE OF THE STUDS

100g WEIGHT

Checking the balance

The rotors have already been balanced in section 6. The wind turbine blades must also be balanced in the same way. When the unit is assembled, you should check the balance again using the new procedure below. This is necessary because the rotor disk may not be perfectly central on the PMG shaft.

 

Repeat the starting test (diagram 43) with each of the four rotor studs in the 3 o'clock position. Try different weights, and find the lightest weight which will start the rotor turning. If one stud needs much more weight than another, then the rotor is not balanced. Fix small weights to the rotor until the balance is correct.

Electrical testing

Coil connection test

It would be helpful to have a multimeter when testing the PMG, but it is possible to do some basic tests with a 3 volt torch bulb. See diagram 44.

• Connect the wires 1 B to 4A, 2B to 5A, and 3B to 6A. (Series connections of pairs
of coils which are in the same phase.)

• Set the multimeter to '1 0VAC' or similar (if you have one).

• Connect the meter, or a bulb, between the wires marked 1 A and 4B.

44. TESTING THE COILS

WIRING DIAGRAM

CIRCUIT SCHEMATIC

BULB OR METER

TEST THESE NEXT

Rotate the PMG slowly by hand, about one revolution per second. The meter should give a reading of about two volts, or the bulb should flicker. Repeat the test with two more pairs of wires: 2A and 5B, 3A and 6B. In each case the result should be the same.

If there is no reading, or a very low reading, then check that the series connections (1 B-4A, 2B-5A, 3B-6A) are correct. If all these connections are good, then it is possible that one coil has been reversed (placed upside-down).

If any coils have been reversed, then it is necessary to do another test (see diagram 45), to find out which one is at fault. Connect 4B-2A and 5B-3A as shown in the diagram. Now test between 1 A and 6B. There should NOT be more than a very small voltage. If there is a voltage, or the bulb lights up, then reverse the connections (swap A for B) on the coils until the voltage drops to a very low level.

When the faulty coil has been found, label the tails again, with A and B at the correct ends.