EP2226515B1 - Limit signaller and method for operating same - Google Patents

Description

The invention relates to a limit signal transmitter for determining a position, such as an end position, a pneumatically operated control valve. Limit switches are often used on safety shut-off valves, which can be pneumatically operated. In the case of a fault operation, the pneumatic drive source is disconnected, whereby the safety closure valve automatically comes due to stored spring energy in an end or safety position in which a fluid line of a process plant by a valve member is either fully open or fully closed.

A conventional limit signal transmitter should be able to indicate to an operator by determining a corresponding signal as to whether the safety valve is actually in the desired end position.

To generate and output the desired signal information, the known limit signal transmitter forms a signal terminal contact, which is generally referred to as a Namur contact. A Namur contact is specified, inter alia, in accordance with the standard "IEC60947-5-6". Should the control armature assume the expected end position, this position input via the signal terminal contact is represented by a current signal of less than about 1.2 mA, for example about 1.0 mA. If the end position is not taken, the Namur contact will show another specific current signal in excess of about 2.1 mA. To generate these two binary switching states, a switching amplifier connected to the Namur contact can be used, to which a so-called proximity switch can be connected. The proximity switch is supplied with a voltage of approximately 8 V and, depending on the switching state, changes its supply current according to the above-mentioned amounts, namely between the above-mentioned limit values 1.2 mA and 2.1 mA. However, if the amount of current at the input of the isolating switching amplifier falls below the value of approximately 0.1 mA or if the input of the isolating switching amplifier is de-energized, this is interpreted as a line break to the Namur contact in accordance with the standard. Then, the isolating switching amplifier according to the standard EN 60947-5-6, a standardized emergency signal of less than 0.1 mA from. Specifies the isolation amplifier However, the standardized emergency signal with a current of more than about 6 mA from, it is assumed that a short circuit at the limit signal generator. The above-mentioned two regular switching states (1.2 mA, 2.1 mA) are displayed and output as standardized switching signals by the isolating switching amplifier, whereby two additional emergency signals, namely a short-circuit signal and a line break signal, can be generated and delivered.

There is a general interest in making simple limit switches "smarter" by providing the limit switch with a microprocessor and a position sensor, while still providing the simple limit switch function. DE 10 2006 049 651 A1 discloses such an intelligent position sensor in which the microprocessor is powered either by the above-mentioned Namur contact supply voltage of 7 to 8 V or by a constant voltage signal of 24 V, which is usually applied to a solenoid valve, which in turn is connected to a pneumatic actuator. An equally intelligent limit switching arrangement is off EP 1 730 611 A1 known.

DE 299 17 651 U1 discloses a transmitter that provides maintenance information about a current signal.

With the extension of the functionality of the limit signal generator, however, there is the problem that, with regard to existing restrictive safety regulations for process plants, the functionality of the intelligent limit switches must be constantly checked and malfunctions must be ruled out as far as possible.

It is an object of the invention to overcome the disadvantages of the prior art, in particular to improve the reliability and reliability of a so-called intelligent limit signal generator.

This object is solved by the features of claim 1 or 2.

Thereafter, a limit signal transmitter for determining two positions, such as two end positions, a pneumatically operated control valve, in particular a safety valve, is provided, which is to assume, for example, a fully open and a fully closed position. The limit switch can also be equipped with a position sensor, For example, an analog-operating Hall sensor or a proximity switch, be provided to detect the position of the control valve, in particular their end positions, preferably for a position control. The limit switch has a first signal terminal contact, for example, may be formed as the first standardized Narmur contact. Furthermore, the limit signal transmitter has a second signal terminal contact, which may also be formed, for example, as a second standardized Narmur contact. Finally, the limit switch has a microprocessor. The limit signal transmitter, in particular the microprocessor, is designed to output an electrical limit signal to the first and the second signal terminal contact, respectively. The limit position signal provides information about the assumption of the first and second positions or at least one different position of the control fitting, if it is above or below a predetermined limit setpoint, which may be below 1.2 mA or above 2.1 mA by name. At least one of the two signal terminal contacts is in particular connected to a switching amplifier for signal transmission of the boundary layer signal which is suitable in the event of a disturbance of the signal transmission, such as a short circuit or a line break, in each case an emergency signal above an upper limit value, which is Namur at about 6 mA, or below a lower limit, which is Namur at about 0.1 mA, to generate and transmit the respective emergency signal to an external process, such as a control room. The limit switch invention provides the multiplication of the Namur contacts at least two additional assignable position signals, namely two additional boundary signals and four additional distress signals (short circuit and line break), and can use these types of signals especially by means of the microprocessor for displaying other operating conditions, as they actually Namur accordingly are generated. According to the invention, upon detection of a specific malfunction of the limit signal transmitter, the control armature and / or a drive actuating the control armature, the microprocessor may execute an emergency procedure for the additional signal terminal contact according to which the specified "emergency signal" (below 0.1 mA, second contact, above 6 mA second contact, etc.) is generated and delivered to the additional signal terminal contact with switching amplifier. This emergency signal actually signals a short circuit or line break, but according to the invention is used to index any predefined operating state.

According to the invention, the microprocessor is thus electrically connected to the second or further signal connection contacts in such a way that when detecting a specific predetermined operating state of the Grenzsignalgebers, the control valve and / or a Stellarmatur actuated drive, so in a relation to the line fault different malfunction, the microprocessor an emergency procedure according to which the typical distress signal is generated, such as above about 6 mA or below about 0.1 mA the second or further signal terminal contacts is given, the receiver of the emergency signal knows to interpret this, ie knows that this typical distress signal is emitted even if the specific operating condition exists.

Essentially, the idea according to the invention consists in outputting the typical emergency signals prescribed by standard EN 60947-5-6 - in the event of a line break or line short-circuit - as another specific error indication signal, to a more or less frequently occurring malfunction not only of the limit signal generator but also the associated components, such as the control valve or the pneumatic drive, display. In the case of the limit signal transmitter according to the invention, it is necessary to provide a second signal terminal contact, because the microprocessor should preferably be energetically supplied exclusively via the first signal terminal contact. An emergency signal delivery for information transmission of other operating states or a line fault at the first signal terminal contact by the microprocessor can not be made insofar as it would also be accompanied by a power supply separation to the microprocessor.

If the limit signal transmitter at the second signal terminal contact an end position signal of, for example, 1.2 mA or over 2.1 mA output and at the same time a malfunction is detected, which requires an actual true distress signal output via the second signal terminal contact, can be provided according to the invention that the higher-level emergency signal overwrites the position signal.

In an alternative, but with the above-mentioned aspect of the invention combinable invention, the invention relates to a limit signal transmitter for determining two positions, such as two end positions, a pneumatically operated control valve. The limit signal transmitter has a position sensor for detecting the position of the control armature, a first signal terminal contact, in particular a first Namur contact, a second signal terminal contact, in particular a second Namurkontakt, and a microprocessor. The limit switch according to the invention is designed to emit in each case an electrical limit signal at the first and the second signal terminal contact. These boundary position signals indicate that the first and second positions or at least one different position of the control armature are in particular slightly above or below a predetermined limit setpoint, such as above or below about 1.2 mA or 2.1 mA. At least one of the signal terminal contacts is in particular connected to a switching amplifier for signal transmission, which in the event of a disruption of the signal transmission, such as a line short circuit or a line break, is suitable for transmitting a distress signal above an upper limit value, such as approximately 6 mA, or below a lower limit, such as about 0.1 mA, and to transmit the distress signal to an external process site, such as a control room. According to the invention, the limit signal transmitter has a third signal terminal contact, in particular a third Namur contact, and optionally further signal terminal contacts, in particular optionally further Namurkontakte. In this case, when detecting a specific malfunction of the limit signal transmitter, the control valve and / or the drive actuating the control armature, the microprocessor executes an emergency procedure with regard to the third signal terminal contact according to which an alarm signal assigned to this malfunction is generated and delivered to the third and optionally further signal terminal contact , The alarm signal can be formed by using one of the typical four signal types of the third or further Namur contact. Thus, this malfunction is due to one of the typical Namur signals above or below the predetermined limit setpoint, such as below about 1.2 mA or above 2.1 mA, or above the upper limit, such as about 6 mA, or below the lower limit, such as about 0.1 mA, uniquely assignable. With this aspect of the invention, four or more (a multiple of four additional individual signals) additional information switching states, less than 1.2 mA, greater than 2.1 mA, less than 0.1 mA, greater than 6 mA, in a simple manner created, and can be used to represent generally malfunction or certain operating conditions of the limit switch or the associated components. The first and second signal connection contacts are preferably not supplied with the emergency signals. The first and second signal terminals may serve to provide the exclusive power supply to the microprocessor.

The invention also relates to an arrangement comprising a limit signal transmitter according to the invention and in each case one switching amplifier connected to the respective limit signal contact.

In a preferred embodiment of the invention, the microprocessor is supplied exclusively via the first, the second or the third signal terminal contact or optionally via only one further signal terminal contact with electrical energy.

In a development of the invention, the microprocessor is connected to the first, to the second and / or to the third signal terminal contact and / or possibly to further signal connection contacts via a cable line such that the emergency or alarm signal generated by the microprocessor can be conducted to the respective signal contact terminal ,

The microprocessor, in particular the limit signal transmitter, is preferably operated only by a constant supply voltage, in particular in the amount of approximately 7 to 8 V, which is applied to one or more signal connection contacts.

In a preferred embodiment of the invention, the limit signal transmitter has an actuating element which can be actuated by an operator in order to set position sensor parameters for the limit signal transmitter on the microprocessor, in particular to activate diagnosis routines, etc.

Preferably, a second microprocessor is provided, which is arranged between the actuating element and the first microprocessor.

In a further development of the invention, the limit signal transmitter has a closed housing, in which in addition to the microcomputer and an electropneumatic transducer (E / P converter), in particular a solenoid valve, is added, wherein the housing has a pneumatic input for connection to a pneumatic source and a Having output for a pneumatic coupling to the actuator. The E / P converter can be connected to the inside output side.

In a preferred embodiment of the invention, means are provided for detecting a voltage signal provided by the microprocessor for the E / P converter, the measured voltage signal indicating the operating state of the E / P converter. The voltage signal can be visualized on a display on the outside of the auto switch.

In a preferred embodiment of the invention, the microprocessor is suitable for differentiating emergency or alarm signals to frequency-specifically clock in particular standardized emergency or alarm signal to deliver a unique for the detected malfunction electrical signal at the respective signal terminal contact.

The invention further relates to a method for operating a limit signal transmitter for determining two positions, such as two end positions, of a pneumatically operated control fitting, wherein in each case an electrical limit signal at a first signal terminal contact, in particular at a first Namurkontakt, and at a second signal terminal contact, in particular a second Namur contact, is delivered when one of the positions or at least one of them different position of the control valve is taken. Both boundary position signals represent the respective position in which a current signal above or below a predetermined limit setpoint, such as below 1.2 mA or above 2.1 mA, is output. At least one of the signal terminal contacts is in particular connected to a switching amplifier for signal transmission, which is suitable in the event of a disruption of the signal transmission, such as a short circuit or a line break, a distress signal above an upper limit, such as about 6 mA, or an emergency signal below a lower limit , as of about 0.1 mA, and to transmit the respective emergency signal to an external process station, such as a control room. According to the invention, an emergency procedure is executed by the microprocessor when detecting a different short circuit and line break disturbance or state of the Grenzsignalgebers, the control armature and / or a Stellarmatur actuated drive, according to which generates an emergency signal in the above-mentioned typical form and on the second Signal connection contact will give.

The invention further relates to a method for operating a limit signal transmitter for determining two positions, such as two end positions, of a pneumatically operated control armature, wherein in each case an electrical limit signal is applied to a first signal terminal contact, in particular a first Namur contact, and to a second signal terminal contact, in particular a second Namurkontakt is discharged when one of the positions or at least one different position of the control armature is taken. Both boundary position signals represent the respective position by outputting a current signal above or below a predetermined limit set point, such as below about 1.2 mA or above 2.1 mA. At least one of the signal terminal contacts is in particular connected to a switching amplifier for signal transmission, which is suitable in the event of a disruption of the signal transmission, such as a short circuit or a line break, a distress signal above an upper limit, such as about 6 mA, or an emergency signal below a lower limit , as of about 0.1 mA, and to transmit the respective emergency signal to an external process station, such as a control room. According to the invention, when detecting a different for short circuit and line break Operating fault of the limit signal transmitter, the control valve and / or a actuator actuating the actuator running an emergency procedure by the microprocessor, according to which a typical alarm or distress signal is generated and delivered to a third or possibly further signal terminal contact, which alarm signal the malfunction by a current either a ) above or below the predetermined limit set point, such as below about 1.2 mA or above 2.1 mA, b) above the upper limit, such as about 6 mA, or c) below the lower limit, such as about 0.1 mA , represents. According to the invention, an emergency procedure is carried out by the microprocessor upon detection of a malfunction or condition of the Grenzsignalgebers, the control armature and / or a actuator armature actuation, according to which a predetermined emergency signal is generated and delivered to a third or possibly further signal terminal contact. The distress signal provides information about the operational disturbance by passing a current signal above and below a predetermined limit set point, such as below about 1.2 mA or above about 2.1 mA, or above an upper limit, such as about 6 mA, or below a lower limit , as indicated by about 0.1 mA, in particular 50 μA.

In a preferred embodiment of the invention, when an emergency signal is generated, an end position signal possibly to be output is overwritten to the second signal input terminal.

It is clear that the method according to the invention can be embodied in accordance with the mode of operation of the limit signal transmitter according to the invention.

Figur 1

ein Blockschaltbild einer ersten Ausführung eines erfindungsgemäßen Grenzsignalgebers und einer pneumatisch angetriebenen Stellarmatur; und

Figur 2

ein Blockschaltbild einer zweiten Ausführung eines erfindungsgemäßen Grenzsignalgebers und einer pneumatisch betriebenen Stellarmatur.

Further characteristics, advantages and features of the invention are explained by the following description of a preferred embodiment with reference to the accompanying drawings, in which:

FIG. 1

a block diagram of a first embodiment of a Grenzsignalgebers invention and a pneumatically driven control valve; and

FIG. 2

a block diagram of a second embodiment of a Grenzsignalgebers invention and a pneumatically operated control valve.

In FIG. 1 is a block diagram of a limit signal generator 1 according to the invention with a solenoid valve 3 indicated that for controlling a pneumatic actuator 5 to the latter connected. The pneumatic actuator 5 is a pivot drive, which is indicated by the circular arrows K. An actuating shaft 7 of the pneumatic actuator 5 extends through an actuator housing 9 to a side of the actuator housing 9 facing the control valve 11.

On the side facing away from the control valve 11 of the actuator housing 9 projects a Stellwellenende 13, on which the first part 15a of a position sensor 15 is arranged, which allows a non-contact tapping the pivot position of the control shaft 7 through the second part 15b of the position sensor 15. The second part 15b of the position sensor 15 is arranged in a closed intrinsically safe housing 17 of the limit signal generator 1. The first part 15a is located outside the housing 17. The position sensor can be designed as a proximity switch or as an analog Hall sensor.

The solenoid valve 3 is connected to a constant 24V supply voltage 19 via a supply line 21. The supply line 21 extends via an input connection 23 into the housing 17 of the limit signal transmitter 1 and leaves the same housing 17 at an output connection 25 from which it is directly connected to the solenoid valve 3. An open / close switch 27 for opening and interrupting the supply line 21 is arranged inside the housing 17 of the limit signal generator 1. The supply line 21 is used exclusively for the electrical power supply of the solenoid valve. 3

The solenoid valve 3 is in pneumatic communication with a 6-bar pressure source 29, which only allows a pressurization of the pneumatic actuator 5, when the 24V supply voltage 19 is applied to the solenoid valve 3. In this "normal" operating situation of the pneumatic actuator, the control valve 11 is in an operating position, which is often defined by a complete opening of a fluid line, not shown, a process plant. The control valve 11 is (not shown) in a fault of the process engineering plant usually automatically moved to a safety position, being used for the process in the safety position internal spring forces of the actuator 5.

Should now fail the 24V voltage or the supply line 21 are interrupted by pressing the switch 27, the solenoid valve 3 vented the pneumatic actuator 5 from the pneumatic pressure source 29, so that the control valve 11 moves by the spring forces in the desired safety position.

The limit switch 1 has, in addition to the input terminal 23, a single power input terminal 33 which is connected to a constant voltage signal supply of 7 to 8V. The constant voltage of 7 to 8 V is provided by a switching amplifier 35. The input terminal 33 is connected via a power line 37 to an internal power supply device 39, which may also be designed as a power supply unit. The power supply device 39 receives the only operating energy for all electrical consumers of the limit signal transmitter 1 only via the power input terminal 33 from the isolation switching amplifier 35.

In the block diagram of the Grenzsignalgebers 1 two arrow types are used, one arrow type with filled arrowhead and another type of arrow with two line arrow legs. The arrows with filled arrowhead represent the electrical energy supply flow of the respective components of the limit signal generator 1. The arrows with line arrow legs represent only possible electrical signal transmission operations.

The power supply device 39 energetically operates not only a microcomputer or microprocessor 41 of the limit signal generator 1 via a power line 43, but also a visual display 45 for operating personnel. The microcomputer 41 also receives position signals of the control shaft 7 from the position sensor 15 via a communication line 49. Likewise, the microcomputer 41 receives from an actuator 51 functional parameters, such as the definition of the end contacts of the Grenzsignalgebers 1 to be detected, activation signals for performing diagnostics, etc. The actuator 51 may be designed as a knob or push button and is manually operable from outside the housing 17 of the limit switch 1. As in FIG. 1 is shown, there is a communication line 53 between the actuator 51 and the microcomputer 41st

In addition, the microcomputer 41 is connected to the open / close switch 27 via an optocoupler 55. By means of the opto-coupler 55, the microcomputer during commissioning or for further diagnostic purposes, the solenoid valve, switch to detect, for example, the end positions to determine delay times or maturities. Even if the power supply to the limit signal transmitter fails at terminal 33, the signal supply to the solenoid valve remains unaffected.

Is the control valve 11 in a normal operating situation, ie the solenoid valve 3 allows a pneumatic pressure of 6 bar in the pneumatic drive 5, so that a Independent spring-driven displacement is prevented in the closed position, the "normal" operating position of the control valve 11 is detected by the position sensor 15 and a corresponding position signal transmitted via the communication line 49 to the microcomputer 41. In accordance with the position signal, the microcomputer 41 outputs a signal below 1.2 mA via the communication line 65 and a signal via the communication line 67 via 2.1 mA, whereby at the terminals 33, 65 corresponding binary limit signal contacts can be tapped, after which the control valve in normal operating position and not in emergency position.

If there is a dangerous accident of the process plant, in which the 24V voltage is no longer applied to the solenoid valve 3 and the pneumatic actuator 5 is vented, the control valve 11 is pivoted to its emergency position, which detects the position sensor 15 and the microcomputer 41 notifies , With the aid of the energetic supply via the switching amplifier 35, the microcomputer 41 outputs corresponding position signals to the input terminals 33, 61, whereby again both a current signal below 1.2 mA at one terminal 65, and a 2.1 mA at the other terminal 31 can be tapped. In this way, it is possible to detect the exact position of the control valve redundantly even with certainty when the power supply of the 24 V is interrupted.

The limit signal transmitter 1 has a further signal input terminal 61 which is connected to an additional isolation switching amplifier 63, which applies a constant voltage signal of 7 to 8 V to the signal input terminal 61. The signal input terminals 33, 61 and the associated switching amplifiers 35, 63 are known as so-called Namurkontakte. The signal input terminal 61 is not used for powering electrical consumers of the limit signal generator 1 but only for generating and outputting a binary information signal on the operation of the limit signal generator. 1

The microcomputer 41 outputs via both input terminals 33, 61 binary signals to a control console, not shown, to indicate whether the control valve 11 is in the predefined limit position. Via the input terminals 33, 61 either currents of less than 1.2 mA or over 2.1 mA are generated, which correspond to the two different binary states.

Should there be a line break or a short circuit at the limit signal generator 1, the switching amplifier 35 is designed to a distress signal in the form of a Current signal below 0.1 mA or greater than 6 mA to detect and deliver this alarm to the control room.

The microprocessor 41 is now designed to signal a different malfunction at the limit signal generator 1, so other than the line break or the short circuit, or even a malfunction of the control valve 11, the pneumatic actuator 5, etc., by at the second Although the typical Namur distress signal via the communication line 65 is used, which actually corresponds to the line break and the line short circuit emergency signal at the signal input terminal 33 from the amount and the signal structure, the distress signal but now alienated to signal another, specific or indefinite malfunction serves. In this way, an operator or the control room is displayed that there is a certain, possibly faulty operating state in the overall arrangement. Subsequently, a diagnostic routine can be initiated by the microcomputer 41 or another logic unit to determine the error origin.

The limit signal generator 1 can also diagnose its operation and / or the operation of the solenoid valve 3 and the pneumatic actuator 5 and the control valve 11. The microcomputer 41 can according to an external control via the actuator 51 or by specially triggered routines perform a diagnostic procedure by the open / close switch 27 is opened via the optocoupler 55 in particular for a short time. In this way, the solenoid valve 3 is vented, whereby the control valve 11 moves from the normal position to the closed position. The desired closing position of the control valve 11 can be checked with the aid of the micro-computer 41, which is still energetically supplied.

In FIG. 2 a further embodiment of the invention is shown, wherein the same reference numerals are used for similar or identical structural and functional parts. The arrangement according to FIG. 2 differs from the according to FIG. 1 in that the solenoid valve 3 is arranged within the closed housing 17 of the limit signal generator 1. In this respect, the housing 17 has both a pneumatic input 71 and a pneumatic outlet 73, which is connected to the pneumatic actuator 5. In this way, a compact, intelligent Grenzsignalgeberstruktur can be provided with the solenoid valve 3. This design may also apply to the design FIG. 1 be taken over. Furthermore, the execution according to FIG. 2 a second microcomputer 75, which is also powered by the power supply device 39 energetically. The second microcomputer 75 receives data from the first microcomputer 41 as well as transmits parameter data to the first microprocessor 41. The second microcomputer 75 is connected to the actuator 51. The second microcomputer 75 is used to query the actuating element 51 and is set in non-actuation of the actuating element 51 in a low-power sleep mode. In this way, the power consumption of the limit switch 1 is low.

The execution according to FIG. 2 is also provided with a fourth electrical signal input terminal 81 which is connected to an external switching amplifier 83, which applies to the signal input terminal 81, a 7 to 8 V supply voltage. This supply voltage is used only for signal transmission and not to power the consumer of the limit signal generator. 1

Four individual signals i ₁ , i ₂ , i ₃ , i _{4 can be} output via the third signal input terminal 81, namely a first current signal i ₁ , which is less than 1.2 mA, a second current signal i ₂ , which is greater than 2.1 mA is a third current signal i ₃ , which is less than 0.1 mA and a fourth current signal i ₄ , which is greater than 6 mA. Thus, normalized Namur contact signals are provided at the third signal input terminal in order to signal individualized different operating failure states from one another. In this case, the microcomputer 41 can be programmed such that it can generate and output a respective individual signal i ₁ , i ₂ , i ₃ and i ₄ for each specific malfunction.

At the second signal input terminal 61, two further distress signals i ₅ , i ₆ for individualized information transmission can also be issued, which are defined by a current signal less than 0.1 mA and greater than 6 mA.

At the in FIG. 2 illustrated embodiment of the Grenzsignalgebers are therefore six additional operating states on the estranged Namurkontakte 61, 63, 81, 83 and their available current signals i ₁ to i ₆ , representable. Furthermore, the "traditional" Namurkontakte 33, 35 and 65, 63 are suitable for the ingestion or not taking the end position of the control valve and the line break as well as a line short circuit specify.

Should one of the distress signals be present at the signal input terminals 33, 65, 81, a diagnostic routine may be executed by the microcomputers 41, 75 to determine the cause of the error.

In order to be able to signal individualized further operating states, the individual emergency signals i ₁ to i ₆ can be individualized by appropriate timing and frequency change.

It is clear that the energy supply to the consumers of the limit signal generator 1 is realized exclusively via the energy input connection 23 and thus via the switching amplifier 35, which applies a constant voltage of 7 to 8 V to the energy input connection 33.

The features disclosed in the foregoing description, the figures and the claims may be of importance both individually and in any combination for the realization of the invention in the various embodiments.

LIST OF REFERENCE NUMBERS

1

Alarm contacts

3

magnetic valve

5

pneumatic actuator

7

actuating shaft

9

Actuator housing

11

Control valve

13

Stem end

15

position sensor

15a, b

Parts of the position sensor

17

casing

19

24V supply voltage

21

supply line

23

input port

25

output port

27

Open / close switch

29

6 bar pressure source

33

Input power port

35

switching amplifier

37

power line

39

Power supply means

41

microprocessor

43

power line

49

communication line

51

actuator

53

communication line

55

optocoupler

61

Signal input terminal

63

Isolating amplifier

65, 76

communication line

71

pneumatic input

73

pneumatic output

75

microcomputer

81

Signal input terminal

83

switching amplifier

K

circular arrow

i ₁ to i ₆

Emergency signals according to Namur contact

Claims (13)

1. A limit signal indicator (1) for determining two positions, such as two end positions, of a pneumatically operated positioning device with a position sensor (15) for detecting the position of the positioning device, a first signal transmission contact, in particular a first Namur-sensor, a second signal transmission contact, in particular a second Namur-sensor, and a microprocessor (41), wherein the limit signal indicator (1) is designed to output an electric limit position signal at the first and second signal transmission contact, respectively, which limit position signals represent the adoption of the first and the second position or of at least one position of the positioning device different thereto above or below a predetermined set limit value such as below about 1.2 mA or above 2.1 mA, wherein at least one of the signal transmission contacts is connected to a switch amplifier of the limit signal indicator (1) for signal transmission, wherein in case of a malfunctioning of the signal transmission, such as a short circuit or a line breakage, the switch amplifier is capable of generating an emergency signal above a maximum limit value, such as about 6 mA, or below a lower limit value, such as about 0.1 mA, and to transmit the emergency signal to an external processing location, such as a control room, characterised in that the limit signal indicator (1) is designed such that, upon detecting a specific operational malfunctioning, being different than the malfunctioning of the signal transmission, of the limit signal indicator (1), the positioning device and/or a drive actuating the positioning device, the microprocessor (41) executes an emergency procedure according to which the same emergency signal is generated and outputted at the second signal transmission contact.
2. A limit signal indicator (1) for determining two positions, such as two end positions, of a pneumatically operated positioning device with a position sensor (15) for detecting the position of the positioning device, a first signal transmission contact, especially a first Namur-sensor, a second signal transmission contact, especially a second Namur-sensor, and a microprocessor (41), wherein the limit signal indicator (1) is designed to output an electric limit position signal at the first and second signal transmission contact, respectively, which limit position signals represent the adoption of the first and the second position or of at least one position of the positioning device different thereto above or below a predetermined set limit value, such as below about 1.2 mA or above 2.1 mA, wherein at least one of the signal transmission contacts is connected with a switch amplifier for transmitting signals, the switch amplifier being suitable in case of a malfunctioning of the signal transmission, such as a short circuit or a line breakage, to generate an emergency signal above an upper limit value, such as about 6 mA, or below a lower limit value, such as about 0.1 mA, and to transmit the emergency signal to an external processing location, such as a control room, characterised by a third signal transmission contact, especially a third Namur-sensor and, if applicable, further signal transmission contacts, especially further Namur-sensors if applicable, wherein the limit signal indicator (1) is designed such that, upon detecting an operational malfunctioning, being different than the malfunctioning of the signal transmitter, of the limit signal indicator (1), the positioning device and/or the drive actuating the positioning device, the microprocessor (41) executes an emergency procedure, according to which an alarm signal is generated and outputted at the third and, if applicable, at further signal transmission contacts, which alarm signal represents the operational malfunctioning either

   a) above or below a predetermined set limit value, such as below about 1.2 mA or above 2.1 mA,

   b) above the upper limit value, such as about 6 mA, or

   c) below the lower limit value such as about 0.1 mA.
3. Limit signal indicator (1) according to claim 1 or 2, characterised in that the microprocessor (14) is electrically powered exclusively via the first, second or third signal transmission contact or, if applicable, via a further signal transmission contact.
4. Limit signal indicator (1) according to one of the claims 1 to 3, characterised in that the microprocessor (41) is connected via an internal cable line with the first, with the second and/or with the third signal transmission contact and/or, if applicable, with further signal transmission contacts such that the emergency signal generated by the microprocessor can be conducted to the respective signal transmission contact.
5. Limit signal indicator (1) according to one of the claims 1 to 4, characterised in that the microprocessor (41) is driven by only one constant supply voltage (19), in particular of about 7 to 8 V, present at one or several signal transmission contacts.
6. Limit signal indicator (1) according to one of the claims 1 to 5, characterised in that it features an operating element that can be actuated by an operation person in order to adjust a positioning parameter for the limit signal indicator (1) at the microprocessor (41), in particular to activate diagnosing routines, etc.
7. Limit signal indicator (1) according to claim 6, characterised in that a second microprocessor (75) is provided, which is disposed between the operating element and the first microprocessor (41).
8. Limit signal indicator (1) according to one of the claims 1 to 7, characterised in that it features an enclosed housing (17) in which, beside the microprocessor (41), also an electro-pneumatic converter (I/P-converter), in particular a magnetic valve, is received, wherein the housing (17) comprises a pneumatic input to be connected to a pneumatic source and an output for pneumatic coupling to the positioning drive, wherein the I/P-converter is connected to the output side at the inside of the housing.
9. Limit signal indicator (1) according to one of the claims 1 to 8, characterised in that a device for detecting a voltage signal generated by the microprocessor (41), provided for the I/P-converter is provided, wherein the measured voltage signal indicates the operational state of the I/P-converter, wherein the voltage signal can be visualised on a display at the outside of the signal indicator (1).
10. Limit signal indicator (1) according to one of the preceding claims, characterised in that the microprocessor (41), for differentiating the in particular standardised emergency or alarm signal, is suitable to clock it in a frequency specific manner in order to output at the respective signal transmission contact an electrical signal that is distinctively identifiable with respect to the detected operational malfunctioning.
11. Limit signal indicator (1) according to one of the preceding claims, characterised in that, if an emergency signal is generated, an end position signal at the second signal transmission contact (2) is overwritten.
12. A method for operating a limit signal indicator for determining two positions, such as two end positions, of a pneumatically operated positioning device, (a) wherein, respectively, an electric position limit signal is generated and outputted at a first signal transmission contact, in particular at a first Namur-sensor, and at a second signal transmission contact, in particular at a second Namur-sensor, when the first or the second position or at least one position of the positioning device differing therefrom is adopted, which both position limit signals represent the positions above or below a predetermined set limit value, such as below about 1.2 mA or above 2.1 mA, (b) wherein at least one of the signal transmission contacts is connected with a switch amplifier for signal transmission which, in case of a malfunctioning of the signal transmission, such as a short circuit or a line breakage, is suitable for generating and transmitting to an external processing location, such as a control room, an emergency signal above an upper limit value, such as about 6 mA or below a lower limit value, such as about 0.1 mA, characterised in that, upon detection an operational malfunctioning, being different than the malfunctioning of the signal transmitter, of the limit signal indicator (1), the positioning device and/or a drive actuating the positioning device, an emergency procedure is executed by the microprocessor (41) according to which the emergency signal is generated and outputted at the second signal transmission contact.
13. A method for operating a limit signal indicator for determining two positions, such as two end positions, of a pneumatically operated positioning device, wherein, respectively, an electric position limit signal is outputted at a first signal transmission contact, in particular a first Namur-sensor and at a second signal transmission contact, in particular a second Namur contact, if the position or at least one position of the positioning device different therefrom is adopted, which two position limit signals represent the positions above or below a predetermined set limit value, such as below about 1.2 mA or above 2.1 mA, wherein at least one of the signal transmission contacts is connected to a switch amplifier for signal transmission, which in case of a malfunctioning of the signal transmission, such as a short circuit or a line breakage, is suitable for generating an emergency signal above an upper limit value, such as about 6 mA, or below a lower limit value, such as about 0.1 mA, and to transmit the emergency signal to an external processing station such as a control room, characterised in that, upon detection an operational malfunctioning, being different than the malfunctioning of the signal transmitter, of the limit signal indicator (1), the positioning device and/or one of the drives actuating the positioning device, an emergency procedure is executed by the microprocessor according to which an alarm signal is generated and outputted at a third or, if applicable, further signal transmission contact, which alarm signal represents the operational malfunction either

    a) above or below the predetermined set limit value, such as below about 1.2 mA or above about 2.1 mA,

    b)above the upper limit value, such as about 6 mA, or

    c) below the lower limit value, such as about 0.1 mA.

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