DE2044329C - Circuit arrangement for automatically keeping the operating voltage constant when transmitting over cables of different lengths - Google Patents

Description

4. Circuit arrangement according to claim 1, that the circuit arrangement according to the invention has characterized in that the control device (28) compared to the above, operated by hand from one of the number of taps of a 40 known arrangement, the advantage that the operating secondary winding corresponding number of devices connected in series, regardless of the connected cable length, mutually automatically those for the telecommunications device locking threshold value switches (42, 43, 44) emits the necessary voltage so that no components stands. damaged in this device due to overvoltage

5. Circuit arrangement according to claim 4, there can be 45. The advantage over the above too by characterized in that the outputs of the first-mentioned, automatically operating known Threshold value switch (42, 43, 44) each via an arrangement consists in the fact that in the case of an interruption impedance converter (46, 47, 48) each with two controls for the cable connection, for example one Electrodes of the controllable switch (2Γ to 26 ') cable change, the voltage is switched off automatically are connected, which will correspond to each other. Because of this, this is usually the tension The corresponding taps of the two secondary winding plug contacts are de-energized, so that the lungs (12, 13) are connected. Operating personnel when touching the contacts

is not endangered. In addition, components in the control gear itself cannot be damaged in the process,

■ 55 there instead of the normally occurring voltage rise in the event of a cable interruption, the voltage is switched off.

The invention relates to a circuit In the following the invention is based on an in

arrangement for automatically keeping the F i g. 1 and 2 illustrated embodiment AC operating voltage in a device of the electrical 60 explained in more detail, with only the understanding of the see communications engineering with symmetrical over- Invention necessary parts are drawn. In Carrying this alternating voltage from an operating unit, the same parts appearing in both figures are included comes from cables of different lengths. provided with the same reference numerals. It shows

When supplying power to devices from FIG. 1 is a schematic diagram of the inventive

electrical communications engineering, for example remote 65 circuitry,

vision cameras, it is important that the cable shown in Fig. 2 the control unit and the switching device in

dependence on the length of the cable occurring more detailed representation. Voltage drop is automatically compensated. In the case of the in FIG. 1 shown circuit arrangement

Γ- ₄

The technical device 7 connected to terminals 1 and 2 should be connected to terminals 39 and 40 AC voltage can be removed after switching on the switch. ctpuerperät

ters3 from the operating device4 via the cable 6 to the Das shown in detail in Fig. 2 ^K f ^ '^'

Telecommunication device 7, for example a 28, contains an impedance converter 41, to whose television camera, regardless of the length of the channel, the voltage generated via the cable core 31 is transmitted. To the automatic failure lies. The output d ^. ¹ ?? ⁰ " ^W * ™." :, _{tern is} equal to the voltage drop occurring on the cable 6 with the inputs of three bcnweiiww * uu is the secondary winding 8 of the transformer 9 in the 42, 43, 44, for example of the type ^d 5?, ^ "L operating device 4, whose primary winding 11 is connected to the gers, whose outputs are uDer '" ¹ ^ mains voltage U _n , divided into two winding halves 12 io converter 46, 47, 48 to the control electronics and 13, with taps 14, 15, 16 and 17, respectively, semiconductors (triacs) 21 and 20 ozw ** 18, 19 provided and connected via controllable switches 21, 22, 25 'or 23' and 24 '. The A ™ ^e "£ 23 or 24, 25, 26 with Ground connectable. Advertising stretch while these controllable semiconductor "™ * / to the switches 21 to 26 are in the switching device 27 from the - g As in F i I the * ^ ™ controller 28 depending on the connected i ₅ ter - between the Taps of the new cable length, with increasing length lungs 12, 13 to ground. V # »rrii» iM ·

controlled so that each switch 21 and 26 or each threshold switch is cgt with a ν em , -

22 and 25 or 23 and 24 are closed. circuit provided and so auigeoaui, aw

As a manipulated variable for the control unit 28, depending on the voltage drop on the cable 6 Jf ^wc " ^s . ^U [." | see the connection points 29 and 30 occurring ao threshold value switch is controlled iina aic urn voltage drop across the cable core 31, which are blocked with the threshold value switch, is the help of the supply of a constant current of a certain cable length of the associated; bcnwc.iwer of the constant current source 32 is generated. Once activated by the switch, these outer ends 33 and 34 of the secondary windings are siand even with voltage fluctuations ms to naui-12 or 13, the 25th shutdown of the cable interruption for the communication technology, ^De " ^s P ' ^es _ft device 7 The required operating voltage U _{s is obtained} via the manner when changing the cable. If the Naoei ο wires 36 and 37 of the cable 6 are symmetrically transmitted, then there is a problem with the tingang avoided within the cable 6 ter blocking voltage, so that the sieuerDdren be. the operating voltage U _s can by transport 30 semiconductor switch 21 'to 26 are non-conductive and transformation by the transformer 38 as power supply voltage transformer ends 33 and 34 no voltage U _Sl , for different parts of the news- is removable.

1 sheet of drawings

Claims (3)

It is already known for television cameras that the voltage drop, which is dependent on the length of the camera cable, is caused by regulating transformers with the aid of motorized 1. Automatic adjustment of the circuit arrangement for automatic adjustment. Such Keeping the operating alternating voltage constant in an arrangement is very complex and extensive, a device of electrical communications engineering so that this is the current trend towards compact construction symmetrical transmission would counteract this alternation. voltage from an operating device via various TV cameras are also known the long cable, characterized in that a transformer with taps is used in that a transformer is installed in the operating device (4), which is connected to the respective connected (U) and two identical, multiple taps (14 cable length can be switched on. Up to 19) having secondary windings (12, but incorrect operation can occur, where-13) is provided that the two outer ends through parts of the operating device or the television (33, 34) of the secondary windings (12, 13) with x ₅ cameras each. In addition, this is connected to a cable core (36, 37) that the order is therefore uncertain and cumbersome, aa taps (14 to 19) via controllable switches the length of the camera cable to be connected in. (21 to 26; 21 'to 26') connectable to ground are generally not immediately detectable is ·. and that a control device (28} for the automatic object of the invention is a circuit. Control of the switches depending on the electrical arrangement to automatically keep constant do tric resistance of a third cable core (31) operating AC voltage in a device of the electrical it is provided in such a way that two each see each other to indicate communications technology in which di. corresponding, · corresponding to the electrical disadvantages mentioned above can be avoided. Resistance of the third cable core (31) according to the invention, a transmission is in the operating device chose taps for the two secondary windings with one of the primary windings fed by the mains are connected to ground. and two equal, several taps open 2. Circuit arrangement according to claim 1, there being provided secondary windings; further characterized in that the two outer ends of the secondary winding are used as controllable switches controllable semiconductor rectifier (2Γ to 26 '), lungs each connected to a cable core and the anin particular Triacs, are used. 30 taps are connected to ground via controllable switches 3. Circuit arrangement according to claim 1, bindable; Finally, there is a control unit for self-winding characterized in that in the operating device (4) gene control of the switch depending on the elekeine Constant current source (32) is provided on tric resistance of a third cable core in such a way which the third cable core (31) is connected so that two corresponding, and that the voltage drop across the third 35 corresponds to the electrical resistance of the third Cable core (31) selected taps of the two sailing devices as control voltage for the control cable core (28) is used. secondary windings are connected to ground.