Overview

Metro is one of the main places of public gathering in modern cities. Once fire happens, it may bring great difficulties to safe evacuation of person in distress and timely rescue of firefighters, which may have a serious effect on the security of citizens’ lives and state property, thus it is necessary to strengthen the safety management of the fire control at metro public gathering places. According to the statistics, among metro fires both at home and abroad, fire accidents caused by electric account for the largest share of fire accidents, up to 37%. Leakage current of power supply line is the main cause of electrical fire.

As the subsystem of automatic fire alarm system (FAS), electrical fire monitoring system is mainly in charge of monitoring and alarming fires which may be caused by power system itself prior to fire. According to the regulations of JGJ 243-2011 Code for Electrical Design of Transportation Buildings, protected objects in case of fire in underground station of urban rail transit are Grade Ⅰ, so electrical fire monitoring system shall be set. It is required that electrical fire monitoring system shall be set during the fire control acceptance and expert review of urban rail transit all over the country at present.。

Reference Standards

GB 50157-2013 Code for Design of Metro

GB 50116-2013 Code for Design of Automatic Fire Alarm System

JGJ 243-2011 Code for Electrical Design of Transportation Buildings

GB 14287.1-2014 Electrical Fire Monitoring System - Part 1: Electrical Fire Monitoring Equipment

GB 14287.2-2014 Electrical Fire Monitoring System - Part 2: Residual Current Electrical Fire Monitoring Detectors

GB 14287.3-2014 Electrical Fire Monitoring System - Part 3: Temperature Sensing Electrical Fire Monitoring Detectors

Application of Electrical Fire Monitoring System in Metro

Electrical fire monitoring detectors mainly consist of residual current electrical fire monitoring detectors (hereinafter referred to as “residual current detectors”) and temperature sensing electrical fire monitoring detectors (hereinafter referred to as “temperature sensing detectors”). Regulations in Chapter IX of GB50116 - 2013 Code for Design of Automatic Fire Alarm System are as follows:

9.2.1 In principle residual current electrical fire monitoring detectors are set at the head terminal of low-voltage distribution system, they shall be set at the outlet terminal of first-level power distribution cabinet (box). When the leakage current of power supply line is greater than 500 mA, residual current electrical fire monitoring detectors shall be set on the power distribution cabinet (box) of next level.

As for power supply system of metro, residual current detectors shall be set in the feeder circuit of 400 V switch cabinet in step-down substation and feeder circuit of environmental control fan in environmental control electrical control room, and temperature sensing detectors shall be subject to corresponding set. Currently, electrical fire monitoring system is set according to the station. Due to the combined setting of fire control room and train control room in metro station, corresponding monitoring hosts are set in train control rooms and at the same time, communication interfaces such as hard wiring interfaces and RJ45 are respectively reserved for FAS and integrated supervisory and control system in the metro station on monitoring hosts to realize the uploading of monitoring information of system.

In the configuration proposal of our company, alarm information and parameters are uploaded to monitoring unit and electrical fire monitoring equipment (hereinafter referred to as “monitoring host”) by residual current detectors and temperature sensing detectors via two-line bus for fire control. Two-line bus for fire control is characterized by long effective communication distance, flexible wiring and non-polarity, supporting star topology, tree topology and bus type topology, thus power supply line and signal line are combined as one to save cost on construction, maintenance and cables.

Brief introduction of system function

Monitoring host can realize the handling, alarm, control, statistics, management and communication of signal of each feeder circuit and can upload alarm information and real-time information of temperature/residual current to integrated supervisory and control system via RJ45 interface. Electrical fire monitoring equipment can receive clock synchronization signal (correct its own clock signal) from the integrated supervisory and control system and commands such as host reset. At the same time, the monitoring host can transmit fire alarm signal from important equipment to FAS system monitoring module via relay output interface and can link special firefighting equipment via automatic fire alarm controller in FAS system.

Configuration Scheme for Metro Electrical Fire Monitoring System

Configuration scheme in single cabinet

Single cabinet is equipped with one SCK630D monitoring unit for centralized monitoring on residual current detector and temperature sensing detector in the cabinet and for uploading of alarm information. The setting of the monitoring unit provides convenience for user to carry out operation and maintenance in the future and for the delivery inspection by complete equipment manufacturer. Simultaneously, the monitoring unit has the function of bus isolator, effectively isolating the faulted communication bus and ensuring the normal operation of other equipment.

The uplink communication port of the monitoring unit of this cabinet is wired to the terminal block of this cabinet, which wiring to monitoring host in metro control room will be carried out together with the monitoring unit of other power distribution cabinets in unified method in site construction stage. For the scheme, a wall-mounted type monitoring host is adopted with small size, which is especially suitable for the use in places with limited space such as the station metro control room. The monitoring host provides the hardwire interface for the station FAS system, and RJ45 communication interface for the station integrated monitoring system, so as to realize the uploading of the system monitoring information.

Scheme characteristics:
1. Fully monitor the residual current and temperature of the related feeder circuits of 400V switch cabinet and environment control cabinet, with flexible configuration.
2. SCK630D electrical fire monitoring unit supports the measuring of 12-circuit temperature.
3. Use SCK600Y integrated residual current detector for electrical fire monitoring, with residual current value transmitted through the two-line bus, effectively avoiding the measurement errors caused by electromagnetic interference, as well as effectively improving the efficiency of operation and maintenance.
4. The monitoring host is equipped with backup power supply, printer, 2 relay outputs and a RJ45 communication interface.

Centralized configuration scheme

For each 400V incoming cabinet, 2 or 3 SCK630 monitoring units shall be set in centralized method (screen installation). A total of 64~96 parameters can be monitored. The monitoring unit of environmental control electric control room is set in a environment control cabinet with a large screen surface, and usually, one SCK630 monitoring unit is suitable for the monitoring of 32 parameters.

The detector is based on the number of monitoring circuits, with SCK600Y integrated residual current detector and SCK600YT temperature sensing detector adopted. SCK600Y and SCK600YT in 400V feeder cabinet of the same bus section are connected to the downlink communication ports of the monitoring unit of incoming cabinet with shielded twisted pair (supporting star topology, tree topology, and bus topology). SCK600Y and SCK600YT in environment control cabinet are closely connected to the downlink communication ports of monitoring unit with shielded twisted pair.

A power distribution cabinet for monitoring unit shall be set, and the uplink communication port of its monitoring unit is wired to the terminal block of this cabinet, which wiring to monitoring host in metro control room will be carried out in unified method in site construction stage. For the scheme, a wall-mounted type monitoring host is adopted with small size, which is especially suitable for the use in places with limited space such as the station metro control room. The monitoring host provides the hardwire interface for the station FAS system, and RJ45 communication interface for the station integrated monitoring system, so as to realize the uploading of the system monitoring information.

Scheme characteristics:
1. Fully monitor the residual current and temperature of the related feeder circuits of 400V switch cabinet and environment control cabinet.
2. Use SCK600Y integrated residual current detector for electrical fire monitoring, with residual current value transmitted through the two-line bus, effectively avoiding the measurement errors caused by electromagnetic interference, as well as effectively improving the efficiency of operation and maintenance.

Product Introduction

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