A high value of alternate current found in the process of alternator diagnostics on the bench or in the car signals the failure either of a rectifier or of stator windings.
Usually, it is a multimeter that is used to test rectifiers. Less often, a rectifier is tested either with a control lamp of several watts, or with a battery, or with a laboratory power unit in a current limiting mode. Besides, each diode must be tested twice as the current should be supplied in both directions - forward and reverse, which is quite inconvenient. A test current of a regular multimeter is 0.002A. This value is too low compared to the diode operational currents. Therefore, this method helps to trace only the most obvious problems such as short or open circuits. In cases, when avalanche diodes (types of stabilitrons) are used in rectifiers, their meaningful diagnostics with a multimeter is not possible as a multimeter-generated voltage is much lower than the voltage of avalanche breakdown diode. So, the traditional methods of rectifier diagnostics with the use of improvised tools proved to be complex, time taking, and inaccurate.
Specialists of MSG Equipment designed Tester MS021 for quick and precise diagnostics of rectifiers. The device tests a diode with a current limited to 900mA and a voltage of 30V which helps to make a precise evaluation of its condition and type. This method doesn’t require reversal of polarity by the equipment operator.
Tester MS021 detects the following:
- short circuit;
- open circuit;
- poor contact of the diode with the conductive busbars;
- diode type (avalanche or regular-type);
- diode degradation (forward voltage drop);
- reverse breakdown voltage of the avalanche diode.
The use of Tester MS021 enables not only to evaluate the rectifier condition but as well to measure all the parameters necessary for substitution of the faulty element. For successful repair, the characteristics of both diodes must be similar. Usually, we keep faulty rectifiers in our workshop as a free supply of diodes. The possibility to diagnose diode degradation is another determining factor for a quality repair.
And, it is exactly the quality that earns trust and loyalty of the customers.
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