DE2347201B1 - Measuring device for measuring the bounce time and the switching time of electromechanical relays whose contacts bounce - Google Patents

Description

The invention relates to a measuring device for measuring the bounce time of working or break contacts and the Changeover time of changeover contacts of electromechanical relays, the contacts of which bounce, with the help of counters that are incremented at a high frequency.

Most of the relays used in telecommunications do not close their contacts immediately and Completely; the contacts open one or more times before the idle state is reached. One such opening and closing several times is called bouncing. Even when opening contacts, the Contact springs overshoot and close again one or more times before they stay open. Even in this case one speaks of bouncing. When using relays, their bounce behavior is often of interest.

The switching time of relays equipped with switching contacts also depends on the bounce time, because the switching time is defined as the time between the first bouncing of the contact side that was actuated first and the last bouncing of the second operated Kon

tact side.

The object of the invention is to provide a measuring device with which the bounce time of working or break contacts and the changeover time of bouncing changeover contacts is measured as precisely as possible. The measuring device should be suitable for serial measurements. The measurement result should be displayed digitally and / or be suitable for evaluation devices such. B. Classifiers od. Like. To control.

ίο It is common knowledge the entire bouncing process to make visible with the help of an oscilloscope. This method is too complex for a series measurement and too slow. It would be conceivable to speed up this process by displaying it on the screen photodiodes are attached to the oscilloscope, which detect the first and last change in the contact state and after converting the result into time units, output the bounce time digitally. This too The measuring method is too complex and too imprecise for serial measurements.

It is also already known, for example from German patent specification 924 645, glow lamps for display to use bounce times. The glow lamp is connected to a voltage below the ignition voltage Voltage placed in series with a choke, whereby the contact to be examined bridges the glow lamp. In addition, a number of capacitors are connected in parallel to the glow lamp, which are optional can be switched into the circuit.

When this contact bounces, the choke generates an additional voltage surge that ignites the glow lamp. In conjunction with the choke, the capacitors indicate the time during which the contact can bounce without the glow lamp being ignited. This method, too, is far too imprecise and requires several capacitor switchings and several test procedures before the bounce duration of the contact can finally be determined.
From the German Auslegeschrift 20 35 187 a method is known in which a clock generator is started when the contact is closed for the first time and two counters are incremented at the same time. While the first counter measures the previously set monitoring period with great accuracy and stops the second counter at the end of this, the second counter is reset to its starting position with every bump. At the end of the monitoring period, the second counter shows the time that has elapsed since the last bounce. The difference between the two times gives the bounce duration.

The measuring device according to the invention uses a different method for measuring the bounce time. It is through it characterized in that the contacts of the relay to be measured via an evaluator with the counter and the counter is connected to an output memory that a gate circuit with the first contact state change opens and allows the frequency arriving from the generator to pass through to the counter and that each further contact state change is regarded as possibly the last contact state change and therefore the current status of the counter is transferred to the output memory while at the same time deleting the previous meter reading stored therein.

The measuring device according to the invention has the advantage that only a single precisely working counter is used needs to become. If the clock frequency of the generator is suitably selected, the measurement result will be without

further arithmetic operations are immediately output in time units.

According to a further embodiment of the invention, the measuring device can not only measure the bounce time, but can also be used to measure the switchover time of relays equipped with switchover contacts are.

In the example of the invention is explained with reference to the drawing. While in FIG. 1 shows a circuit arrangement is shown, with which the measurements of the bounce time and the switchover time can be made, is in Fig. 2 the chronological sequence of the individual switching and measuring processes is recorded. In the drawing only the facilities and timing required for understanding the invention are shown. rs

As soon as the contact E is closed, the relay P responds and actuates its contacts a, r or u. One of these contacts is monitored by the evaluator A connected to it. So that the operation of the working contacts a can be evaluated in the same way as that of the normally closed contacts r, an inverter is assigned to the evaluator A , which inverts the operation of the contacts of one type in such a way that they can be treated in the same way as the contacts of the other type. For example, the normally open contacts a can be routed via the inverter so that they act in the same way as the normally closed contacts r. This inverter can be built into the evaluator A , but it can also be inserted as an additional device in the circuit of the corresponding contact, so that only the one contact to be examined has to be connected to the two terminals of the evaluator.

The two sides of the changeover contact u , like the normally open contacts a and normally closed contacts r shown, can be measured separately. If, however, a changeover time measurement of the changeover contact is to be made, then the center spring of this contact must be connected to one input and the two contact sides of the changeover contact u to the other input of the evaluator A , but the mode of operation of one of the two contacts must be inverted, as already described.

The evaluator A also contains a pulse shaper, which converts the incoming pulses from the contacts to be tested into a form that is required by the subsequent devices for further processing.

With the help of a changeover contact w , the impulses obtained in this way can either be passed on directly to the gate circuit T or via a time filter F. This time filter only recognizes a change in the contact state after a preselectable time, so that bruises shorter than this time are not assessed as such will.

When the first change in the contact state is detected, the gate circuit T opens and allows the counting clocks generated in a frequency generator G to pass through to a counter Z. A now the evaluator determines a re-contact state change resulting from a bruise, the measuring instrument assumes that the '10 possibly the last contact state change. The count is then transferred to the evaluation memory S. If this memory has already saved a counter reading, it is deleted before the new counter reading is entered.

In the meantime, the counter Z continues to count. If further bruises are detected, the last counter reading is transferred in the same way to the output memory 5 until the bouncing process is completed. The last value contained in the evaluation bank S are, at taking into account the frequency of the frequency generator G, the bounce of the examined contact.

Since the counting frequency of the generator G is very high, for example 1 MHz, the counter Z is also incremented at very short time intervals. With most of the known meters, the meter reading cannot be read off perfectly during this switching. To ensure this, however, a control circuit K is assigned to the counter Z, which in a known manner either temporarily stores the value present before the last change in the counter reading or delays the transmission of the counter reading until the counter has been switched on.

After a certain time, for example a certain time after the last change in the contact state or after a measurement time determined in some other way, the gate circuit Γ can be closed again and the measurement thus ended. The time that has elapsed since the last change in the contact state can be taken from counter Z, for example. If, however, automatic locking of the gate circuit T is not provided after a certain time has elapsed, the generation of the counting frequency or the transmission to the counter Z is terminated when the relay P or a contact is replaced.

The timing of the individual switching processes is shown in FIG. 2 shown. The relay P is not energized in state 0, it has responded in state 1 (Fig. 2a). The open position of a contact a and r is denoted by ο and the closed position by ζ (Fig. 2b and 2c). The switchover time UZ (FIG. 2e) and the bounce time PZ ( FIG. 2d) lasts as long as the curve is in position 1.

At the point in time ti , the relay P is activated according to FIG. 2a is excited and at time i6 it falls off again. Accordingly, at time δ, the normally closed contact r closes according to FIG. 2c, in order to adopt its final state at time i3 after a few bruises. A while after that, at instant i4, it closes according to FIG. 2b the first time the working contact a. From time 6 onwards, the working contact remains permanently closed.

When relay P drops out, these two contacts open or close in reverse order. The bounce time of the normally open contact a lasts when it closes from i4 to ö and the closure of the normally closed contact r from / 8 to S, as in FIG. 2d is shown. The opening of these contacts can be represented in a similar way.

With a suitable interconnection of the two contact sides of a changeover contact ades relay P , the changeover time UZ (FIG. 2e) can also be measured. As already described, the working side and the resting side of this changeover contact, one of them via an inverter, are connected to one another. The contact status changes of both contacts are recorded jointly by the evaluator A and controlled by the counter Z accordingly. The first contact state change takes place at time ti or (J and the last at time ö or &. The time between these two points in time can be read from the evaluation memory S as a switchover time or can be sent to a controller for further evaluation.

The timings described so far relate to

to a switching position of the contact w, in which the filter F (Fig. 1) is not effective. When inserting the filter Fin the path of the signals to the gate circuit T all very short bruises are suppressed, such. B. at time i4, ü in Fig.2b and θ in Fig.2c. In these cases, the bounce time is measured to be between fl0 and δ and between f8 and fl2 (FIG. 2d) and the second switchover time is measured between f 11 and 9 (FIG. 2e).

1 sheet of drawings

Claims (5)

Patent claims: 1. Measuring device for measuring the bounce time of make or break contacts and the switching time of changeover contacts of electromechanical relays whose contacts bounce with the help of counters that are advanced at a high frequency, characterized in that the contacts (a, r, u ) of the relay to be measured (P) are connected via an evaluator (A) to the counter (Z) and the counter (Z) to an output memory (S) that a gate circuit (T ) opens with the first contact state change (f4) and allows the frequency coming from the generator (G) to pass through to the counter (Z) , and that every further contact state change (e.g. ö) is regarded as the possibly last contact state change and therefore the current state of the counter (Z) in the output memory (S ) is transferred while at the same time deleting the previous meter reading stored in it. 2. Measuring device according to claim 1, characterized in that the contact effect of the contacts of one type (a) is inverted for the bounce time measurement of different single contacts (a, r). 3. Measuring device according to claim 1, characterized in that for the switching time measurement of switching contacts (u) one side (a) of this contact is connected to the other side ^ after inverting the contact effect. 4. Measuring device according to claim 1, characterized in that a time filter (F) can be connected upstream of the counter (Z) by means of a changeover contact (w) so that bruises which last less than a preselectable time are not counted as such. 5. Measuring device according to claim 1, characterized in that the counter (Z) is assigned a control circuit (K) which, when the current counter reading is transferred to the output memory (S) while the counter (Z) is incremented, for the provision of the to be transmitted Value.