Janak Puri to Palam & indra Gandhi Domestic Airport Under Ground Metro Station

In JUNE 2018 TECHFAB SYSTEMS (AP Sensing Germany’s local representative in India) successfully installed, tested & commissioned the AP sensing make Fiber Optical Linear Heat Detection System in full redundant architecture for monitoring of tunnel temperatures and its variation during congestion and other ventilation system operation modes.

The system monitors and provides maximum temperature values at every 20 meters (Zone) interval according to the tunnel chainage boards mounted at every 20 meter interval in tunnel and activates the alarm when temperature in any zone exceeds the pre-determined value.

Besides providing fire alarm capabilities, the fiber optic Linear Heat solution can activate the ventilation fans to extract smoke from tunnel and draw it away from stations. All alarms and temperature values are exported to a central SCADA platform to monitor potential fires, their sizes and the direction of spread in tunnel.

In terms of fire detection, the sensor cable has the highest priority. The complete system (DTS Device, sensor cable and differently –defined temperature zones along the cable) are configured in accordance with the DMRC Standard.

The Fiber optics based system detects the fire and its precise location as well as the direction the fire is spreading, due to the wind factors in the tunnel. And all the data is updated continuously, providing valuable information for additional firefighting measures.

Key project requirements of the project:

• Very high level of overall system availability.
• Class 1M laser, which is inherently safe and enables continuous operation even in the presence of fiber cuts.
• Open interfaces (TCP Modbus) for easy integration to the BMS SCADA systems.
• Fire monitoring capabilities – able to report temperatures up to 750°C to effectively control counter measures in emergency situations.

Installation-specific highlights:

• All LHDS Controller are used in full redundant ring arrangement.
• The complete tunnel length is continuously monitored by two fully independent controllers located in different Station control rooms to achieve the high availability & redundancy.
• The Fiber optic Linear Heat detection Controller at each station can monitor all of the tunnel space in the 2 neighboring stations.
• Each unit has an integrated LAN/Modbus interface to communicate with the SCADA & remote Metro OCC control center.
• The fiber cable length is mapped to the actual tunnel length to provide accurate location & distance from stations in event of temperature abnormality.