Requirements of Federal Law No. 123 Technical Regulations on Fire Safety Requirements for Warning and Evacuation Management Systems.

Requirements of Federal Law No. 123 Technical Regulations on Fire Safety Requirements for Warning and Evacuation Management Systems.

Requirements of Federal Law No. 123 «Technical Regulations on Fire Safety Requirements» for Warning and Evacuation Management Systems»

The main requirement for warning systems, which strikingly distinguishes Federal Law No. 123 from all previous regulatory documents, is monitoring their operability, in particular, we are talking about monitoring the integrity of warning lines (SP 3.13130.2009, clause 3.4 «..Radio channel connecting lines, as well as connecting lines in the fire alarm system with voice notification must also be provided with a system for automatically monitoring their operability»). Warning and evacuation system control devices have many different functions, among which we can highlight monitoring the circuits of actuators as one of the most important.

Arsenal Bezopasnosti Group of Companies promptly responded to the introduction of the following requirements from May 1, 2009: Federal Law No. 123 was put into effect. The Sonata brand voice notification system was immediately supplemented with two models of voice notification control units: Sonata-KL and Sonata-KLD, which support the function of monitoring the line for breaks and short circuits.

It is worth noting that most often four methods of monitoring load circuits are distinguished in the general classification of monitoring methods:
·         monitoring through additional lines;
·         monitoring by impedance (by installed power);
·         monitoring by address marks;
·         control by direct current using blocking elements.
 
Manufacturers of voice notification units use various methods of monitoring the performance of notification and control lines; let us look at each method in more detail.

1. Monitoring via additional lines.

The general meaning of control through additional lines is contained in the name of this method. The control is divided into two stages (see Fig. 1). At the first stage, the first control line «L1» is checked using the second control wire «Control 2». At the second stage of testing, the control line «L2» is checked using the first control wire «Control 1». The control method itself is This is a control of the alarm loop by direct current, while the end-of-line resistor is installed in the control panel.

Figure 1. Control via additional lines.

Control via additional lines is justified if it is necessary to use alarms from different manufacturers in one system, and if this need is more important than the cost of additional installation costs (the cost of control wires and their installation).
 
Advantages of the method:
— full control of lines along their entire length and the ability to control alarms on the «passage»;
— alarms from different manufacturers are allowed in one system.

Disadvantages of the method:
— additional costs for laying control wires.
— use of the control panel to control the integrity of lines.
 
2. Control by impedance.
The impedance control method is based on measuring the total resistance of the warning line for alternating current. Another name for the method, used by some manufacturers, is “control by installed power”. The control device measures the alternating voltage and current in the warning line, and then calculates the power (as the product of current and voltage) or total resistance (as the ratio of voltage to current). This value is recorded and then the device calculates deviations from it (see Fig. 2).

Figure 2 . Control by impedance (installed power).

Since alternating current is passed through the circuit, in order for the acoustic systems not to reproduce the test control signal, the alternating voltage frequency is selected above the sound barrier audible to the human ear, that is, in the region of 20-30 kHz. A higher frequency will increase the contribution of the reactive component of the communication line to the overall picture and will require higher computing resources of the monitoring device.

The main problem with the practical use of the method is the significant inductive and capacitive components of the warning line, as well as the influence of environmental factors (temperature, humidity, electromagnetic interference). As a result of such influence, the error can be 20 percent or more.
 
Advantages of the method:
— the ability to control the warning line and alarms (especially with a small number of them (error 20%);
— two wires are enough for operation and control.
— there is no need for additional blocking elements.

Disadvantages of the method:
— high cost of the control device;
— high error of the control method, especially with a large number of alarms.

3. Control by address marks.
The principle of operation of the system with control by address tags is very similar to the operation of addressable and addressable-analogue security and fire alarm systems. The essence of the method is that each alarm has its own address, which is transmitted to the control device. Together with the address, the alarm can transmit its status and various other parameters in digital form. It should be noted that this is the most promising method of control today, although its distribution is quite narrow due to the high price (see Fig. 3). The method is mainly used in radio channel voice notification systems.

Figure 3. Method of control by address marks.

Advantages of the method:
— automatic control of the transmission line and alarms;
— control of the alarm status and additional parameters.

Disadvantages of the method:
— high cost of equipment;
— use of alarms only from certain manufacturers.
 
4. DC control.
The DC control method is implemented by increasing the resistance of the sounder (or the primary winding of the sounder transformer in public address systems) to DC by series connection of a blocking element (capacitor). The blocking capacitor is selected with a sufficiently large capacity to avoid narrowing the sound range reproduced by the speaker (see Fig. 4).

Figure 4. Method of control by direct current with blocking elements.

The voice notification units (VBU) of the Sonata trademark use exactly this method of monitoring the notification line.
With this method of control, parasitic power losses are possible when reproducing messages, but in the BRO «Sonata-KL» and «Sonata-KLD» this is excluded by introducing a high-impedance end resistor into the line control circuit. The control itself is maximally simplified and comes down to classic loop control.
 
Advantages of the method:
— reliable control of the notification line along its entire length;
— control of removal of acoustic systems;
— two wires are enough for operation and control.

Disadvantages of the method:
— complexity of control of the operability of the alarm devices themselves;
— when using alarms from other manufacturers, it is necessary to install external capacitors for the control function to work.
 
In general, all the listed methods of monitoring warning lines have a right to exist and differ mainly in the depth of control; the complexity of the control device and the cost of installation work.

Marketer of the Arsenal of Security Group, Poll N. PollNP@arsec.ru,

Technical Director of the Arsenal of Security Group, Voltornist M. tech@arsec.ru