MTB Baumalight QC Series, Руководство оператора

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6 SERVICE AND
MAINTENANCE
6.1 Service
6.1.1 Electrical Tests
Continuity and Resistance Test
The generator has four components that can be
checked using an ohmmeter:
• Exciter stator
• Exciter rotor
• Main stator
• Main rotor
Each of these components is composed of various
windings forming a complete electrical path of
relatively low resistance. Using an ohmmeter,
measure the loop resistance of each component.
Contact Baumalight for specific values for your
machine.
Note: Very small resistance values require
precision equipment to make accurate
measurements; however, a standard ohmmeter
will provide a good indication of winding continuity.
Diode Testing
Note: Stop tractor engine before performing this
procedure.
1. Remove the two main rotor leads and the three-
exciter rotor leads from the rectifier assembly.
The rectifier assembly is now electrically
isolated from the generator. The diodes remain
mounted and the diode leads remain connected
to the terminal posts.
2. Using an ohmmeter or a battery light continuity
tester, place one test probe on the diode lead
terminal post.
3. In succession, touch the other test probe to the
lead screw hole in each heat sink.
4. Reverse the probes and repeat the procedure.
You have now tested the three diodes connected
to this terminal post in both the forward and
reverse direction.
5. Repeat the procedure using the other diode
terminal post.
When the positive test probe is connected to
the diode’s anode and the negative test probe is
connected to the diode’s cathode (forward biased),
the diode will switch on and conduct electricity.
This is observed by a low resistance reading when
using an ohmmeter or the lighting of the bulb when
using a battery light continuity tester. Reversing the
test leads (reverse biased) will result in the diode
switching off and no electricity will be conducted.
The results of these tests should indicate one of
three conditions:
Good diode: Will have a much greater resistance
in one direction than the other. Typical reverse
biased resistance will be less than 10 ohms. The
battery light tester will have the light “on” in one
direction and “off” in the other.
Shorted condition: Ohmmeter reading will be zero,
or very low in both directions. The continuity tester
will have light “on” in both directions.
Open condition: Ohmmeter will have a maximum
(infinity) reading in both directions. Continuity
tester light will be off in both directions.
Diode failure after a 25-hour “run-in” period is
generally traceable to external causes such as
a lightning strike, reverse current, line voltage
spikes, and the like. All 6 diodes are essentially in
the same circuit.
Since determining the remaining life on the diodes
when one fails is difficult, replace the entire rectifier
assembly, rather than individual diodes, to avoid
possible continued failure.
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