SU410333A1 - EQUIVALENT OF RESISTANCE CONTACTS. - Google Patents

Description

one

The invention relates to the field of measurements in radio engineering and communications and can be used to measure the parameters of the electrical contacts of switching, connecting and installation products.

Methods and devices are known for measuring the dynamic resistance of contacts and the dynamic instability of resistance. The apparatus operates in such a way that the contacts in question are exposed to external vibration, and the resulting changes in contact resistance are recorded by an oscilloscope or other measuring device. In this case, the dynamic instability can be numerically estimated by the value

f iaKc amine

D /.

.

where., асс - the most instantaneous value of contact resistance; - lowest instantaneous resistance value;

 - static resistance to 1 contact in the absence of vibration effects.

Set up the aforementioned equipment and periodically check the performance and accuracy of measurements during operation.

CONSTANTLY arises the need for an additional device - the equivalent contact resistance. The prototype of such a device is a calibrated resistor connected to a measuring device instead of real closed contacts. However, such an equivalent can imitate only the static resistance of contacts and does not give an idea of its dynamic instability.

The proposed equivalent is characterized in that said calibrated resistor is connected through a capacitor in parallel with the secondary winding of a transformer, the primary winding of which is connected to an audio generator with fixed output voltage. The third transformer winding is shunted by calibrated resistors, which can be replaced, for example, by means of an electronic switch, which results in a change (including remote) of the level equivalent to DNA instability.

The drawing shows the equivalent circuit. It contains a resistor /, imitating static resistance of contacts, transformer 2 with windings I, II, III, capacitor 3, shunt resistors 4, 5} 6, capacitor 7, switching triodes 8, 9 w. 10 electronic switches, load resistors i} 2 and 75 in the collector circuits of the triodes and the power supply of the triodes 14.

The equivalent is connected to the measuring bench in the same way as the monitored contacts on a four-wire system of terminals, and a, b to c, d. The capacitor 3 protects the transformer from magnetizing the contacts to the load by direct current. The bench readout device registers the equivalent static resistance determined by the magnitude of the resistor / and the equivalent dynamic instability or dynamic resistance determined by the voltage of the sound frequency at the resistor's force clamps. The change in the level of dynamic instability of the equivalent in most cases should be made at the rate of switching of the controlled channels by the switch of the measuring bench. In order to ensure the verification of all the channels of the stand with the minimum number of equivalents, it is advisable to change the level of the dynamic instability of the equivalent remotely with signals coming from the switch of the stand. These signals are supplied from the base of triodes 8, 9 or 10, which connect resistors 4, 5 or 6 in parallel to the winding III of the transformer. Capacitor 7 protects the transformer from direct-current magnetization from source 14.

The advantage of the described remote control equivalent circuit is the elimination of galvanic coupling between control circuits, measurement circuits and an alternating current source. Such a connection increases the measurement error and can disrupt the operation of the measuring apparatus.

Subject invention

Claims (2)

1. Equivalent contact resistance, containing a calibrated resistor, characterized in that, in order to simulate the dynamic instability of the contact resistance, it contains a transformer whose primary winding is connected to an audio generator with a fixed output voltage, and a resistor is connected through a capacitor parallel to the secondary winding, forming a four-wire input connection system equivalent to instrumentation. 2. Equivalent contact resistance according to claim il, characterized in that, in order to change, including remote, the level of dynamic instability of resistance, the third winding of the transformer is connected through a capacitor and calibrated resistors to a switching device, for example electronic switch. : gd 0 00 and in 0 0 0 +