DE102008048929A1 - Testing the detection lines of a hazard detection system - Google Patents

Abstract

A fed with a constant line voltage detection line with n detectors of a hazard alarm system can be reliably checked for inadmissibly high resistance in such a way that the voltage at the end of the detection line is limited by an end module to a value that is greater than the minimum detector operating voltage, and that the quiescent current on the signal line is set by means of this end module to a value which is greater than the sum of the quiescent currents of the n detectors and less than the alarm current of a single detector at its minimum operating voltage.

Description

The The invention relates to a method for testing the reporting lines a security alarm system at least to impermissibly high Resistance by measuring the current on the with an end module completed reporting line and comparing this current with a Setpoint.

The The invention further relates to a hazard alarm system, the Implementation of this examination procedure is, namely an installation with a central office, to the immediate or connected via couplers at least one reporting line is.

Alarm systems have long been designed to be connected to the security control center, in the following short "Central", directly or indirectly connected signaling lines monitored for open circuit 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 and the termination resistance must be. 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 varying voltages for testing purposes and currents is allowed.

By the DIN EN 54 part 13 the requirements for the functionality of the cable-bound transmission paths of a security alarm system have been considerably 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 regulations, that for determining 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, at this condition occurs, then measured 10% diminished and then it is determined if 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.

at a method having the features of the preamble of the claim 1, this object is achieved according to the invention by that the voltage at the end of the detection line by means of the end module on is limited to a value greater than the minimum Detector operating voltage is, and that the quiescent current by means of the end module set to a value greater than the sum of the quiescent currents of the n detectors (n ≥ 1) and less than the alarm current of a single detector at its minimum Operating voltage is.

The core idea of the invention is therefore to considerably increase the quiescent current of the reporting line in comparison to the quiescent current value range, which is monitored according to the prior art, ie the (apparent) total resistance which can be computationally determined as the quotient of voltage and current at the input of the reporting line To reduce the line significantly, but at the same time to ensure that the voltage at the end of the signal line remains sufficiently high that even the last detector at the end of the line remains fully functional. As will be explained on the basis of a numerical example, the test specification in accordance with FIG DIN EN 54 part 13 be fulfilled.

Preferably the voltage at the end of the signal line is limited to a value which is about equal to the voltage at the input of the reporting line minus of the maximum permissible voltage drop in the event of an alarm up to End of the reporting line is.

at a danger alarm system with the features of the preamble of Claim 3 is the above object according to the invention thereby solved that the end module consists of a non-linear circuit, which limits the voltage to a value when the detector line is at rest greater than the minimum detector operating voltage is and which produces a preset current on the reporting line, which is greater than the sum of the quiescent currents all detectors and less than the alarm current of a single detector at its minimum operating voltage.

Provided the at least one reporting line is connected directly to the control center This leads (controlled by its microprocessor) the Examination for inadmissibly high resistance of the reporting line by. As a rule, however, one, but usually several reporting lines not directly but via one or more couplers connected to the central office. In this case leads the respective coupler (controlled by its microprocessor and optionally triggered by a command from the control center) the relevant Examination by.

The Endmodul or the non-linear circuit can very easily from a Resistor in series with a zener diode.

Preferably is in series with the resistor and the Zener diode in addition a temperature coefficient compensating semiconductor device.

This Semiconductor device may be a diode, in particular one to the zener diode identical zener diode in the forward direction, be because identical Zener diodes usually have a very similar amount Temperature coefficients have, however, when operating in the reverse direction and in the forward direction with different signs.

at a preferred embodiment of the hazard detection system z are reporting lines (z ≥ 1) to the control center connected to at least one coupler, the at least one reporting line voltage supplies, via a communication bus with the control center is connected and includes a microcontroller that controls the quiescent current and when one or more detectors respond, one alarm stream each Message line measures and evaluates.

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

1 a state of the art with a resistance completed detection line and

2 a message line terminated with an end module according to the invention.

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 and not drawn detectors or as a reporting line with only a single detector M, the directly to a central office or a Coupler is connected, to be 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.

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.

such Detectors have a working voltage range of z. B. 4 V to about 12 V. The detectors switch on to avoid false alarms Fall below the lower working voltage limit independently and initialize when exceeding the minimum New working voltage. In the alarm state, they generate one in comparison to the alarm current significantly higher alarm current on the reporting line. The alarm current can z. B. at the lowest working voltage around 3 mA, with increasing operating voltage rise and circuitry to a maximum value of 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 working voltage at the detector M. The detector can consequently no alarm current he testify. The test condition that the detection line is able to function again after the total resistance of the line has been reduced by 10% is in the case of 1 not achievable.

In the case of 2 on the other hand, the signaling line is terminated with an end module, consisting of the series connection of a resistor R2, a reverse Zener diode D1 and a forward Zener diode D2.

Assuming for R2 to the value of 1 kΩ, for the Zener diode D1, the zener voltage of 6.8 V and for the Zenerdiode.D2 the forward voltage of 0.6 V, the quiescent current I _R is calculated by the terminal module at a voltage U _E at the end of line of z. B. 9.4 V as

RL – 10% = 387 Ω UL(Alarm) = RL·IA(max) = 387 Ω·8 mA = 3,1 V UMelder(Alarm) = UE – UL(Alarm) = 9,4 V – 3,1 V = 6,3 V Defining an inadmissibly high resistance ("wire breakage threshold") below a quiescent current of 1.4 mA results in the same test conditions as in 1 for the working _voltage U _{detector (alarm)} applied to the (last) detector in the event of an _alarm : U e = I R · R2 + U lock + U passage = = 1.4mA · 1kΩ + 6.8V + 0.6V = 8.8V U L = U A - U e = 9.4V - 8.8V = 0.6V

R L - 10% = 387 Ω U L (Alarm) = R L · I A (max) = 387Ω · 8mA = 3.1V U Indicator (alarm) = U e - U L (Alarm) = 9.4V - 3.1V = 6.3V

Under normal testing, therefore, the voltage at the detector M remains above the minimum working voltage even with an alarm current of 8 mA. The compared to the example of the 1 high alarm current value of 8 mA is therefore important in practice, because often two detectors simultaneously or successively in the alarm state and thus the functioning of the alarm system must not be affected. The detector M in 2 and thus also all other detectors closer to the line start on the same signal line are thus functioning properly if the total resistance of the line is reduced by 10% with the potentiometer RL below the value that the coupler (or the control panel) interprets as creeping wire break and reports.

there takes the end module no power because the reverse voltage of the Zener diode D1 plus the forward voltage for temperature compensation anti-serially connected diode D2, d. H. 6.8 V + 0.6 V = 7.4 V below becomes.

As can easily be shown by calculation, the same behavior is achieved with other than the values for the current and the resistances shown in the preceding example. This applies in particular to a larger number of detectors M, as the following comparison shows: 1 detector RL for wire breakage (= 1.4 mA) : 392 Ω RL - 10% : 353 Ω U _{E (rest)} : 8,85 v U _{E (alarm)} : 6.22V I _A : 7.79 mA 30 detectors: RL for wire breakage (= 1.4 mA) : 796 Ω R _L - 10% : 717 Ω U _{E (rest)} : 8.3V U _{E (alarm)} : 4.91 V I _A : 5.67 mA

The said standard further stipulates that both a creeping as well as a sudden short circuit must be detected. This is done as usual by comparing the reporting line current with preset current limits.

Hereupon, the end module proposed here has an effect only insofar as the current limit values have to be adapted to the higher quiescent current, which is determined by the end module in comparison with the hitherto usual termination of the signal line according to FIG 1 , ie generated with a simple resistance.

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 part 13 [0007]
• - DIN EN 54 Part 13 [0011]
• - DIN EN54 Part 13 [0022]

Claims (8)

Method for testing a signal line fed with a constant line voltage with n detectors (n ≥ 1) of an alarm system at rest to inadmissibly high resistance by measuring the quiescent current of the signaling line terminated with an end module, comparison with a setpoint and generation of an error message if the setpoint is undershot, characterized in that the voltage at the end of the reporting line is limited by means of the end module to a value which is greater than the minimum detector operating voltage, and that the quiescent current is adjusted by means of the end module to a value which is greater than the sum of the quiescent currents of the n detectors (n ≥ 1) and is smaller than the alarm current of a single detector at its minimum operating voltage. Method according to claim 1, characterized in that that the voltage at the end of the signal line is limited to one value which is approximately equal to the voltage at the input of the reporting line minus of the maximum permissible voltage drop up to to the end of the reporting line. Security alarm system with a control center, to which at least a reporting line is connected to at least one detector (M), which is completed with an end module to the message line on Error due to impermissibly high resistance of the reporting line and, in the case of an error, a "fault" signal generate, in particular for carrying out the method according to claim 1 or 2, characterized in that the end module consists of a non-linear circuit (R1, D1, D2), which is in Ru state the detection line limits the voltage to a value greater as the minimum detector operating voltage and the one preset Electricity generated on the signal line, which is greater than the sum of the quiescent currents of all detectors (M) and less than the alarm current of a single detector (M) at its minimum Operating voltage is. Security alarm system according to claim 3, characterized that the circuit consists of a resistor (R1) in series with a Zener diode (D1) exists. Alarm signaling system according to claim 4, characterized in series with the resistor (R1) and the zener diode (D1) their temperature coefficient compensating semiconductor device (D2) is located. Hazard alarm system according to claim 3 or 4, characterized characterized in that in series with the resistor (R1) and the Zener diode (D1) is a diode whose temperature coefficient compensating diode is located. Security alarm system according to one of the claims 3 to 5, characterized in that in series with the resistor (R1) and the zener diode (D1) a zener diode of identical design to the latter (D2) lies in the forward direction. Security alarm system according to one of the claims 3 to 7, characterized in that z signal lines (z ≥ 1) connected to the control center via at least one coupler are that provides at least the reporting line voltage over a communication bus is connected to the center and a Microcontroller includes, which has the quiescent current and at least at least a detector measures and evaluates the alarm current of each reporting line.