Install the generator on the stand and make connections as shown in fig. 7-6. Turn on the electric motor of the stand, set the generator output voltage to 13 V with rheostat 4 and bring the rotor speed up to 6000 min-1. Let the generator run in this mode for at least 10 minutes, and then measure the recoil current.
For a working generator, it should be at least 80 A.
Pic. 7-6. Connection diagram for testing the generator on the stand:
1 - control lamp 12 V, 3 W;
2 - generator;
3 - voltmeter;
4 - rheostat;
5 - ammeter;
6 - switch;
7 - battery.
If the measured value of the output current is much less, then this indicates a malfunction in the stator and rotor windings or damage to the rectifier unit of the generator. In this case, a thorough check of the windings and the rectifier unit of the generator is necessary to determine the location of the fault.
The voltage at the generator output is checked at a rotor speed of 5000 min-1. Using rheostat 4, set the output current to 15 A and measure the voltage at the generator output, which should be 13.2-14.7 V at ambient and generator temperature (25±10) °C.
If the voltage is not within the specified limits, replace the brush holder with voltage regulator with a new, known-good one, and retest. If the voltage is normal, then the old voltage regulator is damaged and must be replaced. And if the voltage still does not fit within the above limits, then it is necessary to check the windings and the generator rectifier unit.