DE1244024B - Circuit arrangement for the automatic setting and setting of a measuring range of electrical current and voltage measuring devices in telecommunication and remote measuring systems - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

Number:
File number:
Registration date:
Display day:

G08c

German KL: 74 b-8/01

1244024
D39265IXd / 74b
June 29, 1962
6. Wed 1967

In information processing systems, in particular telecommunications or telemetry systems, are Measurements are required that are initiated from a point that is far away from the to measuring object "is located, and for which the measurement results are then used to initiate the measurement Place are often transmitted via cordoned off lines for display and / or evaluation.

The invention relates to such a measuring method in which the individual measured values (e.g. of resistances, capacities, external voltages, etc.) for determination, transmission and evaluation can be converted into corresponding voltage values. The economy requires a largely automatic operation of such measuring methods. Here the difficulty arises, which is about a large voltage range (usually over several powers of ten) extending measured value with sufficient Display accuracy. For this purpose, the measuring and display device has several switchable Areas whose setting can be initiated from a remote location either by manually Control commands or by synchronous operation of electromagnetic switching devices that are connected to each Are arranged at the end of the transmission path, is made.

The invention solves the problem of automatically applying the appropriate measuring range with simple means high-resistance connection of the circuit to be tested and with earthed test voltage fixed and set, in that the monostable multivibrator, in the output circuit of which a relay is arranged is dependent on the switching means for range setting of the measuring and testing device Result of a comparison between a measurement voltage that is stored in a capacitor connected to the input of the flip-flop circuit, and a comparison voltage in the flip-flop can be controlled.

To set a measuring range for electrical measuring instruments is by the British patent 701941 only known to make three range settings using several relays. From the US Pat. No. 2,840,408 shows that a servo motor is used for automatic range adjustment is required. U.S. Patent 2,865,000 provides the knowledge to determine to use several capacitors of the measuring range.

In the drawing, the principle of the invention is shown, for example, largely from one schematic representation is made use of

Circuit arrangement for the automatic setting and setting of a measuring range of electrical current and voltage measuring devices in
Telecommunication and telemetry systems

Applicant:

German telephone works and cable industry

Aktiengesellschaft, Berlin, Wrangelstr. 100

Named as inventor:
Peter Konopka,
Günter Weise, Berlin

The arrangement consists essentially of one

ao capacitor C of low capacitance, a monostable multivibrator preferably constructed from transistors TrI to Tr 3, the mode of operation of which is assumed to be known, and electromagnetic switching means PS, SCH, dl, dl. Here, the switching means (relay) PS controls, among other things, the switching means SCH, which successively switches on the individual measuring ranges of the measuring and testing device MP. The contacts dl, dl belong to switching means that switch the desired test and measurement arrangement to the test object MO , and they automatically return to their working position and vice versa after a fixed time unit. The capacitor C is discharged in a known manner, not shown, before each measurement.

In the idle state, the transistor Tr 2 is overdriven, whereby the transistors TrI and Tr 3 are blocked. The device under test MO lies on the lines α and b. The test capacitor C is charged via the contacts dl, dl by the measured value, which can be the full measuring voltage or a partial voltage thereof. When the contacts dl, dl switch to their working position, the voltage stored in the capacitor C is applied to the flip-flop which responds when the voltage across the capacitor C.

4.5 is also only a fraction of a volt smaller than the comparison voltage V (dashed reference line) lying between the emitter of the transistor TrI and the point P 1, which is adjustable and stabilized by a Zener diode ZD.

The capacitor C receives a charging current surge via the emitter-base path of the transistor TrI and via the resistor Wi 1 , as a result of which

■ · = ■ -.-; - '709 609/264

Claims (6)

of the base current pulse, the collector path becomes low-resistance. The transistor Tr 2 is blocked by means of the capacitor KoI charged to the value U. The transistor TrI remains energized, and the transistor Tr 3, which is now also conductive, causes the relay PS arranged in the output circuit to respond. Relay PS initiates the switching of the measuring range in a known manner, not shown, each time the toggle switch is actuated (switching means SCH). By reloading the capacitor JToI via the resistor WiI, the transistor Tr2 becomes conductive again and blocks the transistors TrI and Tr 3 regardless of the voltage on the capacitor C. The contacts dl, d2 return to their rest position, whereby the ~ capacitor C is discharged . The monostable multivibrator is back in its starting position. The relay PS is de-energized and returns to its rest position. It also controlled an arrangement which, after setting the new measuring range, automatically repeats the test until the voltage across the capacitor C is greater than the reference voltage U. In this case the relay PS no longer responds. Now the range set by switching means SCH is the applicable measuring range of the measuring and testing arrangement MP. If voltage values that are too high for the flip-flop circuit (TrI to Tr 3) occur on capacitor C, these are derived via the resistor-rectifier combination Wi 2, GrI. In the case of voltages of incorrect polarity, the base current of the transistor TrI increases only briefly and is limited in a known manner by a resistor. It is also important here that, due to the low capacitance of the capacitor C, the stored energy is also low and is insufficient to damage the transistor TrI. After the measurement has been carried out, the switching means SCH is controlled in its starting position in a known manner, and the entire arrangement is again in the starting position for renewed automatic setting of an appropriate measuring range for further measurements. Patent claims: 1. Circuit arrangement for the automatic determination and setting of a measuring range of electrical current and voltage measuring devices in telecommunication or telemetry systems, which has a monostable multivibrator, in the output circuit of which a relay is arranged, through which switching means for setting the range of the measuring device are adjustable, characterized that the monostable multivibrator (TrI to Tr 3), in the output circuit of which the relay (PS) is arranged, by the switching means (SCH) for range setting of the measuring and testing device (MP) depending on the result of a comparison between a measuring voltage, which in a capacitor (C) connected to the input of the flip-flop circuit (through contacts d 1, d2) is stored, and a comparison voltage (U) can be controlled in the flip-flop circuit 2. Circuit arrangement according to claim 1, characterized in that the capacitor (C) has a low capacity and the voltage stored in each case corresponds to the measured value. 3. Circuit arrangement according to claim 1, characterized in that the monostable multivibrator is constructed with transistors (TrI to Tr 3) and in the idle state a transistor (Tr 2) is overridden and the other two (TrI, TrZ) are blocked. 4. Circuit arrangement according to claim 1, characterized in that the monostable multivibrator (TrI to Tr 3) responds when the voltage of the capacitor (C) applied through contacts (dl, d2 ) is also only a fraction of a volt smaller than that between the Emitter of a transistor (TrI) and the point (Pl) lying reference voltage (U) and thus relay (PS) initiates the switching of the measuring range. 5. Circuit arrangement according to claim 1, 3, 4, characterized in that the monostable multivibrator (TrI to Tr 3) remains in the starting position when the voltage of the capacitor (C) applied by the contacts (dl, dl) is greater than that Equivalent voltage (U). 6. The circuit arrangement according to claim 1, characterized in that (3 TrI to Tr) against excessive voltages derives a resistor rectifier combination (GRI, Wi2) these voltages from the transistor (TrI) for the protection of the flip flop. Considered publications:
British Patent No. 701,941;
U.S. Patent Nos. 2,865,000, 2,870,408. 1 sheet of drawings 709 609/264 6.67 ® Bundesdiuckerei Berlin