Arkori Qingqing

Jiangsu Ankerui Electric Manufacturing Co., Ltd. Jiangyin, Jiangsu 214405, China

Abstract: Building electrical fires account for a large proportion of building fires, and there are many causes of fire, including short circuit, overheating, electric leakage, lightning strikes and electrical faults, and the fire hazard is also large. Therefore, fires caused by various reasons should be effectively controlled. At present, protection measures such as short circuit, overheating and lightning strike are becoming more and more mature, and due to the prevalence of normal leakage current, leakage often does not attract enough attention, resulting in fire. Obviously, the use of leakage current detection, given the fire alarm and warning system is very necessary. This paper introduces the application of Ankerui Acrel-6000/B electrical fire monitoring system in Yutong energy-saving and new energy bus production base production supporting project, analyzes relevant national standards and design specifications, and outlines electrical fire monitoring system in electrical fire prevention. The specific architecture and its superiority.

Keywords: public buildings; electrical fire; Ankerui; electrical leakage;

 

0, foreword

With the continuous improvement of the people’s living standards, the use of electricity continues to increase, but electrical fires have also increased dramatically. This has also caused huge losses to the country’s economy and people’s lives and property. According to the "China Fire Statistical Yearbook" statistics, electric fires rank first in recent years, and the proportion is 30%, and it is rising year by year, causing heavy losses. In fact, electrical fires have become the main disaster-causing factors for fire safety, not only because of the large number of times, but also because of large losses, and they have remained high for many years.

The main causes of electrical fire in public buildings are the following:

0.1 The use of wires in buildings has been in disrepair for a long time, and its insulation has deteriorated.

0.2 The installation of conductors in buildings is not standardized. If conductors are not protected by pipelines, they are buried directly in walls or placed on components.

0.3 When public places such as entertainment venues are in the second renovation, the wires are laid in disorder, causing hidden fire hazards.

The construction quality of 0.4 conductors is rough, and workers cut corners and materials. The use of steel pipe threading is the insulating layer of the wire wound on the inner wall of the steel pipe.

0.5 The line is affected by natural conditions, such as the humidity of the air causing the insulation level of the wire to drop.

In view of the above aspects, Ankerui Electric Co., Ltd. based on its self-developed ARCM series electrical fire monitoring detectors, through the integration of RS485 bus technology and terminal microcomputer software display technology, developed Acrylic Acrel-6000 /B electrical fire monitoring system. The background of the system displays the data of each detection point, and also provides functions such as over-limit sound and light alarm and humanized interface. The system realizes 24-hour unmanned real-time monitoring of the power distribution system, reduces labor costs, and improves the efficiency of eliminating electrical fire hazards.

This paper briefly introduces the practical application of the Acry-6000/B electrical fire system and its practical significance in the application of the electrical fire system in the production project of Yutong Energy Saving and New Energy Bus Production Base.

1. Project Overview

Yutong energy-saving and new energy passenger vehicle production base production supporting project is located in Yutong Industrial Park, Zhengzhou City, Henan Province, east of Qiancheng Road, about 100 meters north of Hongri Road. Total building area: 27167.88 square meters, building layers: underground 2 floors, above ground 12 stories; Building height: 67.65m. Building fire classification: Class I building, Fire rating: Grade 1. Main structure type: Frame shear structure, use function: underground parking garage and equipment room, from one to twelve floors for office. A type of high-rise office building.

The project is divided into administrative office buildings, canteens, research and development centers and underground garages.

Our company selected the residual current type electrical fire detector ARCM300L-J1, the residual current type electrical fire monitoring equipment and the electrical fire monitoring system Acrel-6000 for the project. The system has the functions of centralized scheduling, control, protection, monitoring, display, etc. It has the advantages of intelligent management, control, protection, analysis and recording of electricity, which can greatly reduce the incidence of electrical fires in applications.

A wall-mounted electrical fire monitoring host is installed in the fire control room, and the data of the administrative office building, the canteen, and the research and development center are uploaded to the fire control room background monitoring host.

For the characteristics of this project, in order to prevent electrical fires caused by ground faults, combined with the importance of this project, all lighting and power distribution systems of this project are equipped with a leakage fire alarm system. The system mainly includes a system host, a field monitor, and a data centralized controller. The leakage fire alarm host is set in the fire control room. The system installs a leakage fire detector on the incoming line of the distribution box of each floor, and monitors the leakage current at the place. When the leakage current of the distribution circuit is detected to be greater than 300 mA and the working current exceeds the alarm value set by the time limit, the system issues Acousto-optic alarm signal, accurately report the address of the fault point, monitor the change of the fault point, display its status, and only give an alarm signal to the equipment power circuit, and does not cut off the power supply.

2, reference standards

In view of the fire in public buildings, it is easy to cause loss of life and property. In order to increase the intensity of electrical fire monitoring and control, in recent years, the state has successively formulated or revised a number of relevant standards and specifications. The relevant standard specifications have put forward specific requirements for the electrical fire monitoring system. The design standards for the design of the Acrylic-Acrel-6000/B electrical fire system selected in this project are as follows:

2.1 GB50045-95 (2005 edition) "High-rise Civil Building Design Fire Protection Code", which provisions in Article 9.5.1: High-rise buildings in the fire risk, personnel intensive and other places should be set up a leakage fire alarm system.

2.2 The relevant provisions of the national standard “Building electrical fire prevention requirements and detection methods” also clearly require that “the residual current protection device that automatically cuts off the power supply or alarm should be installed at the power input end.

2.3 The products of the electrical fire monitoring system shall meet: GB14287.1-2014 "Electrical fire monitoring equipment", GB14287.2-2014 "Residual current type electric fire monitoring detector", GB14287.3-2014 "Temperature type electric fire monitoring" detector"

2.4 The installation and operation of the electrical fire monitoring system should meet the GB13955-2005 "Installation and Operation of Residual Current Operation Protection Device"

2.5 The power supply for the electrical fire monitoring system should meet the requirements of GB50052 "Design Specification for Power Supply and Distribution System"

2.6 The design of the electrical fire monitoring system should meet the requirements of the "Design Method for Electrical Fire Monitoring Systems" (Interim Provisions)

3. System architecture and design

Electrical fire monitoring system topology

3.1 Station Control Management

The management of the station control management system for the electrical fire monitoring system is the direct window of human-computer interaction and the uppermost part of the system. The Encore Electric Fire Monitoring System mainframe fully takes into account the user's operating habits and continuous and stable operation, with reference to the corresponding national standards and specifications. The host is mainly composed of monitoring software, touch screen, UPS power supply, printers and other equipment. The site's various types of data information are calculated, analyzed, and processed, and graphically, digitally displayed, voiced, and indicator lights reacted to terminal managers. Enables managers to grasp system dynamics in real time, and realizes functions such as fault information can be traced and information can be exported.

In view of the scale of the instrument point and the amount of data in this project, the Acrel-6000/B host is now configured for the project. The specific parameters of this host are described below.

3.2 Network Communication Layer

All instruments in this project must be connected in a strictly hand-in-hand manner, and all communication buses must be laid along weak bridges. The meters of this project are distributed among the power distribution cabinets on the floors.

The data bus of this project is designed as two buses. The independent bus facilitates the maintenance of the later system. When a leakage current alarm occurs, the fault circuit can be quickly located according to the checklist provided by us in the later stage to quickly eliminate the fault.

The on-site electrical fire detectors use a twisted-pair cable (ZR-RVSP2*1.0) to communicate with each other in a hand-in-hand manner. The number of meters per bus is within 30.

3.3 Field device layer

In this project, the Ankerui rail-type electrical fire detector ARCM300L-J1 is installed for the incoming circuit of the floor distribution box. The leakage current of the distribution circuit is monitored in real time by the rail-type electrical fire detector to display the entire power distribution system. The working state.

The ARCM series residual current type electrical fire monitoring detector is designed for TT and TN systems below 0.4kV. It monitors and manages the fire hazard parameters such as residual current and wire temperature of the distribution circuit to prevent electrical fires. And real-time monitoring of multiple power parameters to provide accurate data for energy management. Products using advanced microcontroller technology, high degree of integration, compact size, easy installation, intelligent, digital, network in one, is the building electrical fire prevention and control, insulation insulation system, such as the ideal choice. The product meets the standard requirements of GB14287.2-2014 "Electrical fire monitoring system Part 2: Residual current electrical fire monitoring detector".

4, system characteristics and working principle

In view of the scale of this project, the actual situation of the project's electrical fire detection point. Whether in the terminal residual current detector or the background host is designed according to the actual situation of the project.

4.1 The system features of this project can be summarized as follows:

4.1.1 Terminal detectors use panel-type electrical fire detectors to facilitate installation, save costs, and facilitate future maintenance.

4.1.2 RS485 bus connection is convenient and operability is strong. When the bus is routed, it is a weak bridge, which is not affected by strong electricity, ensuring stable communication of the entire system.

4.1.3 Taking into account the amount of meter data in this project, customer requirements. The host of this project is wall-mounted. The wall-mounted host has a simple interface and is easy to operate. It is suitable for the distribution room environment and customer related operation requirements in this project.

4.2 Working Principle of Electrical Fire System

4.2.1 Residual current measurement is based on Kirchhoff's current law: At the same time, the vector of current flowing into and out of a node in the circuit is zero. Taking the TN-S system as an example, A/B/C/N is simultaneously passed through the residual current transformer. When there is no leakage in the system, the current vector sum of the residual current transformer flowing into and out is zero. At this time, the residual current The secondary current induced by the transformer is also 0; when a leakage occurs on a relatively large ground, the current vector at the time of flowing into and out of the residual current transformer is no longer zero, and its magnitude is equal to the current flowing from the ground, ie the leakage current. The leakage signal is transmitted to the electrical fire detector through the secondary wiring of the residual current transformer, and is transmitted to the CPU after operation amplification, A/D conversion. After a series of algorithms, the amplitude of the change is analyzed, judged, and The alarm set value is compared. If the set value is exceeded, an audible and visual alarm signal is sent and sent to the background electrical fire monitoring device.

4.2.2 The terminal detector is responsible for monitoring the residual current value of each loop and transmitting the residual current data to the system host. The terminal detector is also responsible for the real-time display of the residual current value of the monitoring circuit, and can set the limit value. When the residual current value exceeds the limit, it can emit an audible and visual alarm to remind the management personnel to maintain and rectify in time.

4.2.3 The instrument transmits data to the system host through the RS485 bus. The system host will upload the data to reflect the running status of the entire system through the form of graphs, reports, and event records.

5, system design considerations and methods

5.1 The electrical fire monitoring system mainly monitors the following two types of objects: residual current and temperature.

5.1.1 About Residual Current

Since the principle of residual current monitoring adopts Kirchhoff's current law, there is a certain requirement for the form of the applied low-voltage power distribution system. At present, low-voltage power distribution systems that can apply residual current transformers are: TT system, IT system, TN-S system, and cannot be used in TN-C system. For users who will design and install an electrical fire monitoring system, whether it is a new project or an old engineering project, first check the system grounding form of the user's low-voltage power distribution system. Otherwise, design and install the residual current transformer. Testing is simply not possible.

With regard to the AC220V single-phase power supply system, the residual current transformer can only cover two L/N power lines, but it is required that the neutral line N is not allowed to be grounded thereafter. For the AC380V three-phase power supply system, due to the use of three-phase three-wire system, three-phase four-wire system, three-phase five-wire system, etc., according to the specific circumstances of the residual current transformer will be at the same time jacketed A / B / C three-phase power line, Or cover the A/B/C/N line at the same time. Similarly, it is required that the neutral line N is not allowed to be grounded after that and the protection line PE must not pass through the transformer.

When the system is grounded in the form of a TN-C type industrial automation network, it must be converted to a TN-S type, TN-CS type, or a local TT type system before the residual current detection device can be installed.

5.1.2 About Temperature

The temperature measurement has nothing to do with the form of system grounding. It mainly considers the temperature of key parts in low-voltage power distribution equipment, including cables, and is generally applied in the secondary protection circuit. The temperature probe Pt100 can adopt the contact arrangement method. When the object to be detected is an insulator, the temperature sensor of the detector should be directly disposed on the surface of the object to be detected. When the detected object is a change in the internal temperature of the distribution cabinet, a non-contact arrangement can be used, close to the heat-generating components.

5.2 Point allocation in system design

According to the provisions of the national standard GB13955-2005 “Installation and Operation of Residual Current Operation Protection Device” 4.4, concerning graded protection, when installing the residual current fire monitoring device, the steps of point allocation principle are:

5.2.1 Study and analyze the relevant drawings of the controlled low-voltage AC380V distribution line, investigate and verify the distribution of building electrical, and determine the location of the distribution equipment (such as power distribution cabinets, boxes, disks, cables, etc.), The monitoring detectors are assigned to the corresponding power distribution equipment to determine the number of detectors and avoid resetting waste.

5.2.2 Determine the hierarchical protection. In order to reduce the range of power failure caused by the occurrence of personal electric shock accidents and ground faults, three-stage (or two-stage) residual current protection devices of different capacities are usually installed at different locations of the power supply line to form hierarchical protection. According to the power load and line conditions, it is generally divided into two or three levels of protection, suitable for urban and rural first and second level protection.

Among them, important routes should include security, fire, emergency power, channel lighting and important places that do not allow power outages.

5.2.3 In the secondary protection, all switches shall be installed with the residual current fire monitoring detector installed, ie at the power end of the line (first level protection) and at the beginning of the branch (second level also called end protection). Install residual current detectors and access electrical fire monitoring systems for fire monitoring alarms only.

5.2.4 Temperature detection is based on the basic principle of heat generation in abnormal distribution equipment.

1) transformer low voltage side outlet terminal, transformer body temperature (wind temperature, oil temperature, water temperature) test point, load switch contacts.

2) Access points of the power distribution cabinets (boxes), contact points of automatic switches (circuit breakers, knife switches), concentrated current conductors, and cable connection points.

3) Master contact, knife switch contacts.

4) Compensation capacitor terminals and transfer switch contacts.

5.2.5 According to the total number of points installed, select the appropriate wall.

6, the configuration of system parameters

6.1 Setting range of alarm value

The residual current alarm value of the field instrument in this project is set at 600mA, and the setting of the residual current value has detailed provisions in the relevant national standards.

According to the provisions of the national standard GB14287.2-2014, the alarm value of the residual current electrical fire monitoring detector is set in the range of 20~1000mA. According to this requirement, the residual current action value at the power supply main line is generally set to 400~800mA, and the residual current action value on the power branch line is set to 100~400mA. Generally, the residual current type electrical fire monitoring detection is set at the actual site. The alarm value of the device shall not be less than 2 times the maximum value of the leakage current during normal operation of the protected electrical circuit and equipment, and shall not be greater than 1000 mA. Electrical fire detectors' alarm settings should take into account the normal leakage currents of the distribution system and electrical equipment.

6.2 About the cable temperature rise alarm setting reference, according to "power cable design specifications" on the cable temperature requirements

6.2.1 Locations above 60°C should withstand high temperatures and their duration and type of insulation. Heat-resistant PVC cables, cross-linked polyethylene or ethylene-propylene rubber insulation, etc. should be selected. High temperature above 100°C. Insulated cable. High-temperature places should not use ordinary PVC insulated cables.

6.2.2 The ambient temperature of the continuous allowable current carrying capacity of the cable shall be determined according to the multi-year average of the meteorological temperature of the area of ​​use and shall comply with the regulations. When laying the cable trench in the house, the ambient temperature is the average value of the day's hottest month temperature plus 5°C.

6.2.3 The temperature rise of the cable is related to the laying and heat dissipation conditions.

7 major equipment parameters

Yutong energy-saving and new energy bus production base production supporting project consists of the electrical fire monitoring equipment Acrel-6000/B, leakage current fire detector ARCM300L-J1 leakage current transformer AKH-0.66L.

7.1 Main Technical Parameters

7.1.1 Power Supply:

1 rated working voltage AC220V (-15% ~ +10%)

2 Standby power supply: When the main power supply is under voltage or power failure, maintain the monitoring equipment working time ≥ 4 hours

7.1.2 Work system:

24-hour work

7.1.3 Communication Methods:

RS485 bus communication, Modbus-RTU communication protocol, transmission distance 1.2km, can extend communication transmission distance through repeater

7.1.4 Monitoring Capacity:

1 monitoring equipment can monitor 1024 (to be customized) monitor unit (detector)

2 can be connected with ARCM series monitoring detector

7.1.5 Monitoring Alarm Items:

1 Residual current fault (leakage): fault unit attribute (part, type)

2 Temperature alarm (over temperature): Fault unit attribute (part, type)

3 Current fault (overcurrent): Fault cell attributes (part, type)

Monitoring alarm response time: ≤30s

Monitoring alarm sound pressure level (A weighting): ≥70dB/1m

Monitoring alarm light display: red LED indicator, red light alarm signal should be maintained until manual reset

Monitoring alarm sound signal: Can be eliminated manually, when it is alarm signal input again, it can start again

7.1.6 Fault Alarm Project:

1 The communication cable between the monitoring device and the detector is open or shorted.

2 Monitoring equipment main power supply undervoltage or power failure

3 An open circuit or short circuit occurred in the connection between the battery charger and the battery

Fault alarm response time: ≤100s

Monitoring alarm sound pressure level (A weighting): ≥70dB/1m

Monitoring alarm light display: yellow LED indicator, yellow light alarm signal should be maintained until troubleshooting

Fault alarm sound signal: can be eliminated manually, when the alarm signal input again, can start again

During faults, normal operation of non-failed circuits is not affected

7.1.7 Control Output:

Alarm control output: 1 set of normally open passive contacts, capacity: AC250V 3A or DC30V 3A

7.1.8 Self-inspection project:

1 Indicator Check: Alarm, Fault, Operation, Main Power, Standby Power Indicator

2 display check

3 audio device inspection

Self-check time ≤60s

7.1.9 Event Recording:

1 Record content: record type, occurrence time, detector number, area, fault description, no less than 20,000 records can be stored

2 record query: according to the record of the date, type and other conditions

7.1.10 Operational Rating:

1 daily shift: real-time status monitoring, event record query

2 Monitoring operation level: real-time status monitoring, event record query, detector remote reset, device self-test

3 System management level: real-time status monitoring, event record query, remote reset of detector, device self-check, system parameter query of monitoring equipment, individual detection of each module of monitoring equipment, operator addition and deletion

7.1.11 Use environmental conditions:

1 Workplace: fire control room, manned power distribution (distribution room), on-call room walls

2 working environment temperature: 0 °C ~ 40 °C

3 working environment relative humidity: 5% to 95% RH

4 Altitude: ≤2500m

7.2 Basic functions

7.2.1 Monitoring alarm function:

The monitoring equipment can receive the leakage and temperature information of multiple detectors. When the alarm sounds, an audible and visual alarm signal is emitted. At the same time, the red “alarm” indicator light on the equipment is on. The display indicates the alarm location and type of alarm, records the alarm time, and the sound and light alarm keeps Until the display resets the detector remotely. The audible alarm signal can also be manually cancelled using the display “Mute” button.

7.2.2 Failure alarm work

Communication failure alarm: When a communication failure occurs between the monitoring device and any connected detector, the corresponding detector in the monitoring screen displays a fault prompt, and the yellow “fault” indicator light on the device is on, and a fault alarm sound is emitted. .

Power failure alarm: When the main power supply or standby power supply fails, the monitoring device also emits an audible and visual alarm signal and displays the fault information. You can enter the corresponding interface to view the detailed information and cancel the alarm sound.

Check that all status indicators, display, and speakers in the device are normal.

7.2.4 Alarm record storage query function

When leakage, over-temperature alarm or communication or power failure occurs, the alarm part, fault information, alarm time and other information are stored in the database. When the alarm is cancelled or the fault is eliminated, the same is recorded. Historical data provides a variety of convenient and fast methods for searching.

7.2.5 Power Function

When the main power supply has a power failure, undervoltage, etc., the monitoring equipment can automatically switch to the standby power supply. When the main power supply returns to normal power supply, it automatically switches back to the main power supply, ensuring continuous and smooth operation of the monitoring equipment during the switching process.

7.2.6 Probe Control Functions

By monitoring the software operation, remote reset control can be performed on all detectors connected to the device.

7.2.7 Rights Control Function

In order to ensure the safe operation of the monitoring system, the monitoring device software operation authority is divided into three levels, and different levels of operators have different operation rights.

Conclusion

In summary, the electric leakage fire alarm system can accurately detect the faults and abnormal conditions of the electric lines, and can discover the hidden dangers of fire in the electric fires. The timely alarm reminds the personnel to eliminate these hidden troubles. From the perspective of building safety, the design of building leakage fire alarm system is very important. In the long run, the electric leakage fire alarm system can be used as a subsystem in the fire automatic alarm system, so as to realize the combination of strong and weak electric power in a real sense, and constitute a perfect fire automatic alarm system.

references

[1]. Ren Zhicheng Zhou Zhong. Principles and Application Guide of Digital Measurement of Electric Power Measurement [M]. Beijing. China Electric Power Press. 2007. 4

[2]. Zhou Zhong. Application of power meter in electric energy metering of large public buildings [J]. Modern Building Electric 2010. 6

[3]. Anyang Shenyang Fire Research Institute. GB 50116 - 2013 Fire Alarm System Design Specification [S]. Beijing: China Planning Press, 2014

[4]. Department of Fire Services. Fire Safety Technology Practice [M]. Beijing: Mechanical Industry Press, 2014.

   

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