DE102008048930A1 - Testing the detection lines of a hazard detection system - Google Patents

Abstract

The method involves measuring the current of the alarm system loop, and comparing with a reference value. An error report of the shortfall of the reference value is generated. A testing current is generated at the alarm system loop by the terminal module periodically during testing period. The alarm system loop is supplied with a constant line voltage. The testing current is equal to the current of an alarm. The generation of the testing current by the terminal module is activated for a time tolerated by the alarms by breaking and re-switching the line voltage. An independent claim is included for a danger alarm system, which has a central unit.

Description

The The invention relates to a method for testing one with a Constant line voltage fed signaling line with n detectors (n ≥ 1) an alarm system at rest to inadmissible high line resistance (Rx) by measuring the current of one End module completed signaling line, comparison with a setpoint and generation of an error message when the value falls below the setpoint.

The The invention further relates to a hazard alarm system, the Implementation of this examination procedure is, namely a plant with at least one headquarters, to the at least one reporting line with n detectors (n ≥ 1) is connected and that is terminated with an end module to the reporting line for errors due to impermissibly high resistance (Rx) check the signaling line and in case of failure to generate a signal "fault".

Alarm systems have long been designed so that the to the security control center, in the In the following, "Central", directly or indirectly monitored lines for interruption and short circuit can be. Common practice is the quiescent current monitoring, in which the respective reporting line with a resistance of z. B. 10 kΩ is completed. The central office or the coupler Measures the quiescent current in the relevant test mode Detector line and compares it with a tolerance field in which the measured current taking into account the line resistance, the number of connected detectors and their respective quiescent current as well as the termination resistance. Too low power is considered as unacceptably high series resistance, in extreme cases as an interruption, too high a current as unduly lower Parallel resistor, in extreme cases interpreted as a short circuit.

From the EP-A-1 777 671 it is known that a line for feeding z. B. from signalers or other low-impedance consumers (actuators) of a security system to monitor so-called creeping interruption and so-called creeping short circuit. For this purpose, the line with a non-linear element, for. B. a thermistor, a diode or a voltage-controlled transistor in series with a resistor and is operated to test with respect to the triggering of the signal generator (or other actuators) reverse polarity and different, impressed currents. The respectively set voltage at the beginning of the line is compared with reference values. As a result, the comparison provides whether the line is in a proper or faulty state.

A similar monitoring method for a line that feeds at least one alarm device of a hazard alarm system is known from DE-A-10 2005 060 123 known. For this purpose, the line with a low-resistance element, for. B. a diode or a diode in series with a Zener diode, which locks in the current flow direction in which the alarm device is activated blocks. Furthermore, a similar nonlinear element is connected in parallel with each alarm device. For testing, the line is operated with reversed polarity and different impressed currents, from which, in conjunction with the respective voltages at the beginning of the line, the line resistance is calculated and compared with a setpoint range.

These both known test methods are not transferable to reporting lines, because neither the polarity reversal of the supply voltage of a reporting line nor their Operation with voltages changing for testing purposes and Flow is allowed.

By the DIN EN 54 Part 13, the requirements for the functionality of the wired transmission paths of a hazard detection system have been significantly increased. In particular, a standard-compliant installation must ensure that each transmission path under normal load conditions to the relevant component (eg actuator or sensor) supplies the voltage necessary for the function of this component. In contrast to the known systems and their test methods, it is therefore necessary to test for an inadmissibly high resistance of the line under load in the case of a system corresponding to the aforementioned standard. A reporting line must therefore be checked for operability with the connected detectors.

The Testing is in accordance with the rules that to determine a creeping interruption an adjustable Series resistance (potentiometer) in the line of the reporting line so long is increased until the hazard alarm system an interruption the reporting line determines that the total resistance of the line, when this condition occurs, measured, then decreased by 10% and then it is determined whether the reporting line again is functional.

Of the Invention is based on the object, a method and a hazard detection system to make available according to these specifications determine if the reporting line is functional.

In a method having the features of the preamble of claim 1, this object is achieved by ge triggers that by means of the end module periodically during a test period Test current that is at least equal to the current of a detector in alarm condition is generated on the detection line.

Of the The core idea of the invention is therefore the previous monitoring the value of a constantly flowing quiescent current by monitoring a momentarily flowing, in comparison to the previous quiescent current value high test current to replace. It is therefore checked whether the condition of the beginning is satisfied that the transmission path, d. H. the relevant reporting line, even at its end a tension provides, at which the functioning even from the point of view of the last detector still ensured is. Under the operability of a detector is included to understand that the detector in the case of a detected hazard, z. B. a fire, an alarm generated on the signal line, which is many times higher than the quiescent current on the affected Reporting line is. The method proposed by the invention is thus equivalent to an inspection of the reporting line on inadmissibly high resistance under load conditions. If the test time is short, z. Between 10 ms and 30 ms chosen and the repetition of the check of the detection line at long intervals, z. In the range of 10 s to 100 s, the power consumption is low. The procedure is therefore not at the expense of the prescribed Emergency operating time of the hazard alarm system.

in principle could be the test current generated by the end module transmitted by a via the reporting line to the end module encoded command are triggered. Much easier and therefore it is preferred to generate the test current by means of of the end module by interrupting and reconnecting the line voltage for a time tolerated by the detectors. This is the property of most detectors exploited, for reasons the interference immunity also large fluctuations in the Line voltage including a loss of line voltage for a short time, z. B. up to several hundred milliseconds, to tolerate and only at a longer break the line voltage to turn off when the line voltage returns to reinitialize.

A Improvement of the proposed method is the test current only to be generated when the voltage applied to the end module voltage is higher than a predetermined minimum value. This minimum value is preferably equal to the minimum operating voltage of the message line connected detectors, plus a small tolerance value.

in the Normal case, d. H. in a functioning alarm system at rest and one properly installed Signal line with normal line resistance is at the end module almost the same voltage as at the beginning of the signal line is fed. Before the test current is generated, Consequently, the predetermined minimum value of the voltage applied to the end module Voltage will only be undercut if the reporting line line due to damage a very high line resistance has or is even completely interrupted. The central office or the coupler to which the relevant reporting line is connected is, then detects that no test current is generated. From that to distinguish is the case that the reporting line a Resistance, in which at the end module while at rest a voltage between the voltage at the beginning of the line and the Minimum operating voltage of the connected detector is present, this Voltage, however, when the test current is triggered of line resistance falls below the minimum value and Consequently, the test current is not generated or only for a very short time becomes. The control panel or the coupler recognizes in this case that the Test current at least not throughout Check time is present and therefore generates an error message.

Because the alarm current generated by a detector in alarm condition increases with increasing Line voltage initially increases approximately proportional to voltage, from a given line voltage, however, for the sake of Limit the power to a constant value, Preferably, the test current is generated limited current.

at a danger alarm system with the features of the preamble of Claim 5 is the object mentioned in the present invention solved that the end module comprises a timer, by Applying the line voltage is started and a constant current circuit controls, which generates a test current that is at least equal the current of a detector is in alarm. The central office or the Coupler to which the reporting line is connected, includes this a controlling software, which by periodic interruption of the Line voltage for z. B. a few milliseconds the timer of Periodically starts the end module and then checks whether the test current in the predetermined height and present during a given test time is. The test time can z. B. between 10 ms and 100 ms lie.

Preferably the end module has a voltage monitor which is the end module shuts off if it falls below a minimum voltage. This voltage monitoring can be very simple z. B. by one in the current path of the constant current circuit lying Zener diode can be realized with a suitable Zener voltage.

to Avoidance of an installation error due to reversed connection of the end module to the reporting line can at the entrance of the end module a Rectifier bridge be arranged as reverse polarity protection. This measure is known to the person skilled in the art.

Between The input terminals of the end module can be a reporting line termination resistor lie. The reporting line terminator has the existing one Danger alarm system usual value, that is z. B. 10 kΩ. Then the end module is also for the Extension of an existing alarm system usable, the only carrying out the conventional closed-circuit current monitoring, So from the functionality of the proposed end module can not make use of it. The installer or operator of the hazard detection system Consequently, it does not have to be in the embodiment when it is expanded pay attention to the end module.

The Invention is applicable to both systems in which a central office via a communication bus at least one coupler is connected, to which in turn at least one reporting line is connected, as even in the rarer case, that one or more reporting lines are directly connected to the control center.

in the The invention is compared with the prior art explained with reference to the drawing. It shows:

1 a state-of-the-art signaling line terminated with a resistor,

2 The circuit of an end module for carrying out the method according to the invention

3 : a current / voltage diagram for checking a signal line with an end module according to 2 ,

The two-wire reporting line in 1 , in the following also briefly "line", comprises a detector M and a terminating resistor R1, which is very often equal to 10 kΩ. Within the scope of the invention 1 as the end of a reporting line with numerous other, parallel to the detector M are the not shown and not shown detectors or as a reporting line with only a single detector M. which is connected directly to a central office or a coupler, are considered. In addition, a potentiometer RL is looped into the detection line to those mentioned by the above DIN EN54 Part 13 prescribed test conditions to creeping interruption of the reporting line to simulate.

These Signaling line has in normal operating condition, ie without the potentiometer RL, assuming a line voltage of 9.4 V, a quiescent current of about 900 μA plus the quiescent current of the detector M of z. 20 μA, with n detectors plus n x 20 μA.

Often such detectors have an operating voltage range of z. B. 4 V to over 12 V. Switch to avoid false alarms the detectors fall below the lower operating voltage limit usually independently and initialize when exceeded new to this minimum operating voltage. Create in alarm condition they are considerably higher in comparison to the reporting rest Alarm current on the signal line. The alarm current can z. B. in the lowest operating voltage around 3 mA, with increasing Operating voltage rise and circuit technology to a maximum value from Z. B. 8 mA from 7 V be limited.

U_E

= Spannung am Leitungsende

U_L

= Spannungsabfall über der Leitung

R_L

= Leitungswiderstand plus eingestellter Widerstandswert RL;

UE = IR·R1 = 700 μA·10 kΩ = 7 V; UL = UA – UE = 9 V – 7 V = 2 V;

RL – 10% = 2,58 kΩ (Bedingung der Norm); If a quiescent current I _R of less than 700 μA measured at the beginning of the signal line, ie generally in the coupler, at U _A equal to approximately 9 V per definition should be considered a sign for an inadmissibly high resistance ("wire break") and consequently the resistance value of Potentiometer RL is increased until the quiescent current I _{R has} fallen to 700 uA, then:

U _E

= Voltage at the end of the line

U _L

= Voltage drop across the line

R _L

= Line resistance plus set resistance RL;

U e = I R R1 = 700 μA x 10 kΩ = 7 V; U L = U A - U e = 9V - 7V = 2V;

R L - 10% = 2.58 kΩ (condition of the standard);

If, consequently, the line resistance is reduced to 2.58 kΩ with the potentiometer RL and the functionality of the reporting line is required, and above all in the event of an alarm, ie at a current I _A equal to approximately 4 mA (sum of quiescent current plus detector alarm current), then one obtains purely mathematically: U L (Alarm) = R L · I A = 2.58 kΩ x 4 mA = 10.32 V;

Consequently, even at a current corresponding to the minimum alarm current I _A, more than the input voltage U _E would drop across the total resistance formed by the potentiometer set by the line and in accordance with the test condition of the standard. Then there is no operating voltage at the detector M. The detector can therefore generate no alarm current. The test condition that the signaling line is functional again after the total resistance of the line has been reduced by 10%, in the case of 1 not achievable.

According to the present proposal takes the place of the resistance R1 of 10 kΩ in 1 an end module, which is used to test the total resistance of the signal line, ie the two-wire line in 1 , but temporarily a detector such as the detector M in 1 simulated. Like the detector M, the end module also works with the circuit according to FIG 2 in this state as a current sink, so that the central unit or the coupler measures a test current during proper conduction during the test time and determines by comparison with a setpoint that is greater than the alarm current of a detector, whether a detector in the alarm state leads to a current, the central unit or the coupler is then detected as an alarm current and processed as an alarm signal when the alarm current persists for a predetermined minimum time. In particular, the test time can be shorter than this minimum time so that the control center does not mistakenly treat the test current as an alarm current. However, the distinction between test current and alarm current is also possible in other ways by software technology. In addition, the end module is designed so that it generates no current during the test time when the voltage at its input is less than the minimum detector operating voltage. If detectors are operated on the same reporting line, the minimum operating voltage is different, the voltage at which the end module no longer generates power, of course, adapted to the highest, minimum required operating voltage.

The circuit in 2 has a rest state and a working state in which it generates the test current. At rest, the circuit assumes a quiescent current at a line voltage at its input, which is higher than the above minimum voltage, which is considerably smaller than the minimum alarm current of a detector. In order to put the circuit in the working state, the coupler (or the control panel) interrupts the line voltage for a short time interval, e.g. For 4 ms. Normally, the detectors connected to the line are in the idle state and tolerate this voltage interruption because they internally draw their operating voltage from a buffer capacitor during this time.

The Circuit has a timer at the input. As a result of a break the line voltage has a time determining capacitor C11 over R51, Discharge R28 and R32. The discharge time can be reversed shortened parallel to C11 diode, in particular in connection with the later explained resistance R52. With the return of the line voltage, C11 holds the PNP transistor Q29 via R51 in the locked state. That's why the NPN transistor is Q19 in the locked state. Consequently, the NPN transistors Q23 and Q24 conduct, which together with the resistors R25 and R26 a constant current source form. This is designed so that it has a power consumption, which is at least equal to the minimum alarm current of a detector M, but preferably twice, so z. B. is about 9 mA, provided that the voltage applied to the input of the circuit line voltage greater than a minimum voltage. This is through a Zener diode D11 in the collector branch of Q23 and one for temperature compensation series-connected normal diode D16 determined. If D11 is a Zener voltage of 5.1V and D16 has a forward voltage of 0.6V hence the circuit only at input voltages higher than are about 6V.

Meanwhile C11 has so far charged that Q29 again permeable which also makes Q19 permeable. This switching from Locked state accelerates to the permeable state the feedback resistor R50. Because Q19 is now permeable is, the base of Q23 is grounded across R25, with the result that the constant current source now blocks.

The central (or the coupler) solve the test described periodically off, z. In a cycle between one second and one Minute.

The circuit can optionally have a parallel resistor R52 of 10 kΩ at the input. This resistance has only the function to make the final module compatible with the assumption of an additional quiescent current consumption when used in a standard system for a system that still with a simple quiescent current test according to 1 is working.

This results in the in 3 illustrated current / voltage curve. After each line voltage is switched off and on again, the end module supplies a current pulse of 9 mA in this example during a time of approximately 25 ms determined primarily by C11 and R32, then a quiescent current of approximately 1.3 mA (of which approximately 900 μA) R52 are conditional). Setting the test current pulse to 9 mA ensures that the detector line supplies the detectors with sufficient operating voltage even if two detectors have gone into alarm simultaneously or in succession.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1777671 A [0004]
• - DE 102005060123 A [0005]

Cited non-patent literature

• - DIN EN 54 [0007]
• - DIN EN54 [0025]

Claims (10)

Method for testing a constant line voltage signal line with n detectors (n ≥ 1) of an alarm system at rest for inadmissibly high resistance (R _L ) by measuring the current of the signaling line terminated with an end module, comparing with a setpoint and generating an error message at Falling below the setpoint, characterized in that by means of the Endmoduls periodically during a test time a test current which is at least equal to the current of a detector in the alarm state, is generated on the reporting line. Method according to claim 1, characterized in that that generating the test current by means of the end module by interrupting and restarting the line voltage for a time tolerated by the detectors is triggered. Method according to claim 1 or 2, characterized that the test current is generated only when that at the end module applied voltage higher than a predetermined minimum value is. Method according to one of claims 1 to 3, characterized in that the test current limited is produced. Method according to one of claims 1 to 4, characterized in that the test current during the test time measured at least twice and with the setpoint is compared. Method according to one of claims 1 to 5, characterized in that the test time is shorter as the time is during which a detector will be in alarm must trigger an alarm. Security alarm system with a control center, to which at least a signaling line with n detectors (n ≥ 1) is connected and which is completed with an end module to the message line to errors due to impermissibly high resistance (Rx) of the reporting line and, in the case of an error, a "fault" signal generate, in particular for carrying out the method according to one of claims 1 to 6, characterized the end module comprises a timer (Q29, C11, R32, R31, R51), which is started by applying the line voltage and a constant current circuit (Q23, Q24, R25, R26) which generates a test current, which is at least equal to the current of a detector in the alarm state. Security alarm system according to claim 7, characterized the end module has voltage monitoring (D11, D16) includes the end module falls below a minimum voltage off. Security alarm system according to claim 7 or 8, characterized through a polarity reversal protection bridge at the input of the end module. Security alarm system according to one of the claims 7 or 8, characterized in that between the input terminals of the end module is a reporting line terminating resistor (R52).