Firealarm system scheme

Our lead project engineer presents for review a working project for the automatic fire alarm system in a university building.

Cost-Effective Fire Alarm System Project Development

The protected facility is a three-story university building. The height of protected premises does not exceed four meters. The building is equipped with a heating system, maintaining air temperature above +15°C. Protected areas are classified as fire hazard category B due to combustible materials including furniture and office equipment.

Fire Alarm System Regulations

Understanding Fire Alarm Systems

FA stands for Automatic Fire Alarm System. The system in our example integrates with the building's overall fire safety system through dry contacts via input-output modules.

The fire alarm system installation serves the following purposes:

• automatic fire detection in protected areas;
• transmission of "Fire" and "Fault" signals to security personnel;
• issuing command signals to activate fire safety engineering equipment within the building's integrated system.

The automatic fire alarm system consists of the following components:

1. Two-wire communication line controllers;
2. Fire damper control and monitoring units;
3. Central control and programming unit;
4. Workstation and monitoring software;
5. Loops with addressable analog detectors.

Equipment selection and placement comply with current design standards and regulations. Based on room characteristics and fire load, protection is provided using smoke detectors and manual call points installed along evacuation routes.

Smoke detector signals are monitored through current measurement in detection loops.

During initial fire stages with smoke presence, corresponding detectors activate. Signals are transmitted via two-wire communication lines to the respective controllers, which process the information and relay appropriate signals to the security workstation. Signals include:

• Fault and system failure;
• Fire alarm.

The workstation displays activated or faulty detectors with room-level precision, indicated on the project plans. Through relay output modules, signals are transmitted to the main fire alarm system as shown in the table below.

Fire Alarm System Signal Summary Table

Upon receiving a FAULT signal, the building dispatcher notifies the maintenance service and directs fault resolution. Upon FIRE signal reception, the dispatcher implements necessary engineering equipment control procedures, either manually or automatically, as defined in the building's fire safety measures documentation.

This project scope excludes connection modules to the central fire detection system, the modules themselves, and reprogramming of the existing system.

System components include:

1. Two-wire communication line controller;
2. Addressable analog smoke detectors;
3. Addressable manual call points;
4. Redundant power supply unit;
5. Cable network.

Owner Installation Project Data

Integrated Security System

The primary information collection and processing system uses monitoring and control software.

The system is designed for:

1. Collecting, processing, transmitting, displaying and recording security, panic and fire alarm loop status;
2. Access control and management of barriers including gates, turnstiles, doors, etc.;
3. Video surveillance and monitoring of protected objects;
4. Building automation control;
5. Engineering systems management;
6. Voice alarm system control.

The fire alarm monitoring system provides:

1. Modular structure suitable for both small and large distributed facilities;
2. Cost-effective per loop or access point;
3. Secure communication protocol between console and devices;
4. Microprocessor-based smoke detection signal analysis for sabotage prevention;
5. Single credential capability for arming/disarming and access control.

Control Panel Purpose

The cost-effective fire alarm control panel is designed to monitor status and collect information from system devices, maintain event logs, indicate alarms, and manage fire automation. The panel integrates connected devices into a unified system, ensuring their interaction.

Main Fire Controller Functions:

• Monitoring up to 127 devices connected via communication interface;
• LCD display, non-volatile buffer storage of all system events and printing via serial interface;
• Fire hazard alarm signaling via built-in sounder;
• Remote monitoring of alarm loop status;
• Device configuration parameter programming, configuration printing, device and addressable device address setting;
• Access restriction to management and programming functions via passwords.

Additional configurable functions:

• Loop grouping into sections
• Display of section names and user identifiers in event logs
• Section arming/disarming and status monitoring from panel and keypads
• Permission management based on password system
• Automatic relay output control according to section status with delay capability
• Section status indication management on indicator units
• Event transmission to keypads for display and telephone line communicators
• Computer connection for event logging and status display
• Interface conversion capability for configuration without additional converters
• Workstation backup mode, automatically assuming control during computer disconnection
• Multiple subsystem integration capability with workstation software

Control Unit Technical Specifications

• Maximum connected devices via communication interface: 127
• Maximum sections: 255
• Maximum alarm loops: 512
• User passwords: 511
• Automatically controlled relay outputs: 255
• Event buffer capacity: 1023 messages
• Communication line length: up to 4000 m
• Printer interface length: up to 20 m
• Power supply voltage: 10.2 to 28.4 V
• Typical standby current consumption: 50 mA at 12V, 25 mA at 24V
• Keyboard: 16 backlit keys
• Display: backlit LCD, 16 characters
• Operating temperature range: +1 to +40 °C
• Dimensions: 146 x 105 x 35 mm

Interface Repeater Purpose

The cost-effective interface repeater with galvanic isolation converts communication signals, extends and isolates communication lines with short-circuit protection. Power is supplied from computer or external source.

Interface repeater versions differ by operating temperature ranges. The device is designed for continuous 24/7 operation.

Interface Repeater Characteristics

The repeater operates by transmitting information between interface lines with automatic direction determination. The LED indicates normal operation. The device supports multiple transmission speeds set according to configuration table.

The device provides protection against communication line short circuits: sustained logic zero due to short circuit isn't transmitted to other lines. Normal operation resumes upon detecting logic one. The LED indicates short circuit condition.

Technical Specifications

Power supply: +5 V from computer;

• 10 to 28 V from additional source; Maximum current consumption: 160 mA from computer;
• 120 mA from 12 V source;
• 60 mA from 24 V source.

Temperature range:

• Standard version: +1 to +45 °C;
• Extended version: -40 to +45 °C;
• Relative humidity: up to 93% at +40 °C;
• Dimensions: 150 x 103 x 35 mm maximum;
• Weight: 0.2 kg maximum.

Relay Module Purpose

1. The cost-effective signal relay module is designed for fire alarm and access control systems, working with control panels or computers. The module manages actuators, lamps, sirens, fire suppression systems, electromagnetic locks, etc., transmits alarm signals to monitoring stations via relay contact opening, and provides interaction with other devices and systems at relay level.
2. The module enables remote control of four relays via communication interface, each with switched normally closed and normally open contacts.
3. The module is designed for indoor installation and continuous 24/7 operation.
4. The design isn't suitable for aggressive environments, dust, or hazardous locations.

Relay Module Operating Characteristics

The module is powered by external DC power source, 12V or 24V nominal.

Power consumption: maximum 4W. Current consumption: maximum 150mA. Number of control relays: 4. Maximum switched current per relay: 2A. Maximum switched voltage: 100V. Maximum switched power: 30W per relay.

The module indicates relay status via LED indicators. Deactivated relays show closed normally closed contacts and open normally open contacts with corresponding indicator off. Activated relays show open normally closed contacts and closed normally open contacts with indicator on.

The module transmits alarm signals and status information via communication interface, and executes commands from network controller or computer. Transmitted messages include:

• "Power failure" - Supply voltage out of range;
• "Power restored" - Voltage normalized;
• "Tamper alarm" - Module enclosure opened;
• "Tamper restored" - Enclosure closed."

Events occurring more than 60 seconds before transmission due to communication failure are transmitted with actual time from internal clock. Internal clock synchronization occurs via time synchronization command.

The module buffers events transmitted via communication interface. Buffer size: 55 events. The module executes commands received via communication interface:

• "Relay control" - Activate relay per programmed sequence;
• "Write configuration";
• "Read configuration";
• "Assign network address";
• "Time synchronization".

The module enables activation, deactivation, and switching of built-in relays according to programmed sequences via communication interface commands.

Proper Alarm System Power Supply

Fire alarm systems are classified as Category 1 power consumers, requiring uninterrupted power from two independent AC sources. Power is supplied from 220V 50Hz AC network through guaranteed power source. All metal components of low-current systems must be grounded according to electrical installation requirements.

University Equipment Placement

Fire alarm system placement and installation must comply with project specifications and installation standards. Central fire alarm equipment is located in building security rooms with permanent duty personnel.

Cable Communication Description

All fire alarm system cable connections use cables specified in equipment and materials documentation, installed in PVC corrugated conduits above suspended ceilings.

Contractor Work Execution and Acceptance Procedure

Installation and commissioning must comply with project requirements and installation standards. Acceptance of construction, installation and concealed works must be commission-based and documented according to regulatory requirements.

Grounding Purpose

All metal parts of automatic fire alarm equipment normally not energized but potentially energized due to insulation failure must be grounded according to project drawings. Protective grounding resistance must not exceed 4 ohms. Grounding must be implemented according to electrical installation requirements.

Maintenance Work Implementation

Only personnel trained in safety procedures are permitted to maintain fire alarm systems. Training completion is recorded in logbooks. Installation and repair work in electrical networks, low-current systems, or nearby areas, including wire connection and disconnection, must be performed with power disconnected. Electrical technicians must be provided with protective equipment that has passed appropriate laboratory tests.

All electrical installation work, electrical equipment maintenance, testing frequency and methods for protective equipment must comply with electrical installation operation and safety regulations.

Environmental Impact Source

The installed fire alarm system equipment doesn't constitute an environmental hazard source. Special environmental protection measures are not required.

Civil Defense Measures Project Pages

The fire alarm system design assignment contains no specific civil defense or emergency measures requirements.

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