SU114902A1 - Device for measuring the magnitude of the reverse current of semiconductor rectifying elements - Google Patents

Description

When mass sorting of semiconductor rectifying elements (in particular, selenium ones), protection against unloading of devices that measure reverse current is necessary, due to the fact that the presence of individual elements with reduced reverse resistance or even short-circuits is inevitable. Typically, such protection is provided by a relay that shuts down the protected device in the event of a high current flow. However, when the protection relay trips the device. ceases to act, and it is not possible to determine the nature of the defect of the element (reduced reverse resistance due to the element under-shaping or its short circuit) and, therefore, to establish a method for eliminating this defect (additional molding or unfolding of the element).

The proposed device for measuring the reverse current of semiconductor rectifying elements, containing, as well as known devices, a maximum ammeter protection relay against overload and a voltmeter to control the input voltage and determine the nature of the defect of the test element, has a high output voltage resistance , and thus ensures high measurement accuracy.

The peculiarity of this device is that the normally open contact of the indicated maximum relay is connected to the connection point of the voltmeter with its added resistance, and when the relay is activated, it connects the voltmeter to the element under test.

In the drawing, depicting the circuit diagram of the proposed device, indicated: P - maximum relay, micron A - ammeter, B - voltmeter, R - additional resistance, I - the test element.

If the reverse current of the test element U is less than the permissible ammeter current, then it flows through the latter. In cases where this current exceeds the value acceptable for an ammeter, relay P is triggered and the current of the element being measured does not flow through the AC, DC, ammeter µA, and through the resistance R of the voltmeter. A voltmeter B measures directly the voltage across the element U, so that the voltmeter indicates the nature of the defect of the element and how to eliminate it. The installation of the relay P must be such that it operates at a current that is 1.5 times higher than the maximum current on the scale of the current ammeter and is released at a current exceeding this value by 10-20%.

Subject invention

A device for measuring the magnitude of the reverse current of semiconductor rectifying elements, containing its maximum relay for protecting the ammeter and voltmeter to monitor the input voltage and determine the nature of the defect in the test element, different; This is so that: in order to improve the measurement accuracy by using measuring voltage sources with low output impedance, the normally open contact of the maximum relay is connected to the connection point of the voltmeter with its added resistance, and when triggered, the relay connects the voltmeter to the test item.