MIL-PRF-19500/404C
4.5.3 Peak transient reverse power. The circuit on figure 3 or a similar circuit, at the option of the supplier, shall be used to apply a
single cycle reverse power surge to discrete diodes. The reverse power surge used to test discrete diodes may be applied in the form of
a one-half sinusoidal pulse of 8.3 milliseconds duration.
4.5.4 Internal corona testing. Internal corona testing shall be conducted on all rectifier modules (see figure 4). The method of corona
detection, measurement and display shall conform to the following requirements:
The terminals shall be connected together and connected to the high potential side of the corona test equipment. A test voltage of 25
kV(rms) at 60 Hz shall be applied between the terminals and the ground plane which shall be no more than 2 inches from the major
diameter of the rectifier module. The test potential shall be applied for not less than 20 seconds. The corona tester shall be a Biddle
Company Catalog No. 661409 AC Corona Tester, or equivalent. The corona discharge as viewed on the Biddle tester display screen
shall show no more than 50 discharges per cycle (whole ellipse). None of the 50 discharges shall exceed 5 picocoulombs. In order to
minimize the masking of internal corona by any external corona, rounded terminal hardware of suitable design may be added to the
connectors during the corona test. In addition, the test may be performed with the unit either entirely or partially immersed in a suitable
dielectric fluid in order to reduce external corona.
4.5.5 External corona testing. The method of corona detection, measurement and display shall conform to the requirements of ASTM
D1868. The apparatus shall consist of a corona-free high-voltage adjustable power supply, a corona-free pickup network consisting of a
high-pass filter, a corona detector consisting of a high-gain amplifier/oscilloscope, and a calibrating means to make quantitative
measurement of corona magnitude in picocoulombs. Using the scheme shown on figure 5, an external corona test shall be conducted on
two diode modules of the same rating connected in opposition from 0 V to the required test voltage of:
20 kV(peak) = 14.14 k Vrms for diode module type 1N5597.
10 kV(peak) = 7.07 k Vrms for diode module types 1N5600 and 1N5603.
With a corona detector sensitivity of 1 picocoulomb per 0.1-inch minimum, no corona discharges exceeding 5 picocoulombs shall be
visible for types 1N5597 and 1N5600 and no corona discharges exceeding 15 picocoulombs shall be visible for type 1N5603. The
number of detectable discharges shall not exceed 50 per cycle (whole ellipse).
4.5.6 Avalanche (bulk-breakdown) characteristic. The reverse breakdown characteristics shall be viewed on an oscilloscope with
display calibration factors of 5 to 20 µA/division and 50 to 200 V/division. Reverse current over the knee shall be at least 50 µA. Each
device shall exhibit a sharp knee characteristic and any discontinuity or dynamic instability of the trace shall be cause for rejection.
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