Larkin M5500, Руководство пользователя

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CAUTION
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The part to be tested must be Isolated & De - energized! Connecting the tester to live equipment
will damage the tester.
This equipment operates at voltages as high as 6400V.
Under no circumstances should the equipment EVER be operated without using the 3 wire line
cord, plugged into a properly grounded outlet.
The equipment must be operated in strict accordance with the operating instructions. The pro-
cedures are set up so that the voltage is turned to zero before a test is started.
Do not touch, or allow anyone else to touch, the test leads or the device under test while the
TEST BUTTON IS PRESSED!
THE “ ART ” OF TESTING POWER SEMICONDUCTORS
Manufacturers of power semiconductors follow the test methods outlined in the JEDEC sub -
committee JC22 for SCRs and Diodes. The standard for SCRs is RS397. One of the most im-
portant conditions of this test is that the rated voltage MUST NOT be exceeded.
An ideal SCR or Diode can have voltage applied until the device reaches avalanche voltage. In
practice, many devices have soft breakdown, “ punch through ” or surface breakdown before the
rated leakage current is reached. For these devices, exceeding the rated voltage established by
the manufacturer may result in instant failure or in down grading of the blocking characteristics.
Large devices have round silicon chips which have been beveled and contoured to reduce the
voltage stress at the device junctions at the end of the chip. These devices generally reach ava-
lanche voltage or “ punch through ” before breakdown occurs at the surface.
Small devices on the other hand are made from square chips. These devices are not protected by
the above methods and many will break down at the edge of the chip before avalanche voltage
is reached. This form of breakdown is almost always “ fatal ”
SUMMARY
DON ’ T use an OHMMETER
DON ’ T use a HI POT tester
DO use a tester that conforms to the JEDEC standards
NEVER exceed the manufacturers blocking voltage rating!
NEVER exceed the manufacturers leakage current rating!
If the maximum leakage current is reached before the rated blocking voltage is reached, STOP!
If the rated blocking voltage is reached before the rated leakage current is reached, STOP!
If possible, observe the E/I characteristics of the device on a X - Y oscilloscope.