4.1 Introduction
Safety and Security is a growing need throughout the world, and lack of safety and security can result in great damage of properties and even lost of lives. Today’s security required the use of Automation System devices that can be integrated in our buildings to provide security and safety alert to the concern persons (Monitoring Station). These suggested devices are connected to the Programmable Logic Controller (PLC) and the later is to be connected to the master PLC in the control room via Ethernet switch to be discussed later.
4.2 Security devices
Simple intrusion detection is probably the most familiar concept of security to most people. Intrusion detection involves the use of door or window contacts, glass break detector, motion sensors, in combination with some type of audible alarm that sounds when a person has forced entry into a student’s room or other building within the hostel. An alert is sent to the monitoring station (Manager’s office) or security desk to notify authorities of the time and location of the incident. Security officers respond in person to evaluate the situation.
The following sensors ware proposed for this design based on their sensing range or detection area and their efficiency in detecting the specified change in parameter.
4.2.1 Passive Infrared motion detector (PIR)
Passive Infrared sensor (PIR) is an electronic device that detects and measures infrared light radiating from an object in its field of view. All objects with a temperature above absolute zero degree emit heat energy in the form of radiation.
Figure 4. 1 PIR motion sensor
Usually this radiation is invisible to the human eye because it radiates at infrared wavelengths, but it can be detected by electronic devices designed specifically for such a purpose. The term “Passive” in this instance means that the PIR sensor do not generate or radiate any energy for detection purposes, but merely passively accepts incoming infrared radiation. “Infra” meaning below our ability to detect it visually with our eyes, and “Red” because this colour represents the lowest energy level that our eyes can see before it becomes invisible.
4.2.2 Glass break detector
A glass breakage detector can help ensure safety and security in buildings and homes. It is a simple mechanism to detect illegal entry through glass windows and doors of our buildings.
Glass break detector is a sensor work using two different technologies which are acoustic detection and shock detection.
Acoustic detection senses the sound of breaking glass and triggered an alarm when a noise occurs that is on the same decibel level as the sound of breaking glass, while a shock detector or surface-mount sensor, senses and respond to the vibration and shock of breaking glass. These sensors can be used to provide a security in our home or hostels when we are away from home and during night time to alert us on the presence of an intruder trying to access or enter our premises.
Glass break detector is to be placed at the edge corner of the window, because the sensor senses the sound or vibration of the glass which is concentrated more at the edge corner. Certain natural obstacles such as high speed air, and other thinks has been put into considerations before choosing the right sensor.
Figure 4. 2 Glass break detector
Vibration window sensors work by monitoring windows for vibration. When a window is struck by an object, it vibrate before shattering, which sends an alert to the alarm or monitoring system.
These systems are particularly useful for non-opening windows, but they can be set off by natural events, such as birds flying into the window or hail and high wind. Sensitivity settings may allow you to adjust the level of vibration that sets off the alarm.
4.2.3 Door/Window contact
The ultimate purpose of developing an electromagnetic door lock is to enforce security features of the student’s rooms to prevent unauthorized entry during class hours, holidays and other times which the students engaged in some particular activities outside the hostel area.
Door sensors are magnetic switches that activate an alarm signal when a door is opened, after the system is placed into “armed” mode. They are also commonly called contacts, and can be used on windows as well.
Figure 4. 3 N/O Reed switch
Figure 4. 4 N/C Reed switch
The switch is mounted on the door and the magnet is mounted to the frame directly in line with the switch. This holds the switch in closed position. When the door is opened, the switch moves away from the magnet, causing the switch to open, which in turn cause the alarm panel to activate an alarm signal indicating an intrusion.
Magnetic door contact work on the principle of Reed switch which come in two varieties called normally open (normally switched off) and normally closed (normally switched on). They are normally open contact and normally closed contact. The normally open contact has two contacts which look like metal reeds that are made from magnetic material. One of the contacts (blades) is a magnetic north pole, while the other is a South Pole and vice-versa. As you bring a magnet up to the switch, it affects the contacts in opposite ways, attracting one and repelling the other, so they spring together and a current flow through them. While the normally closed contact type the two contacts are normally separated. When you bring a magnet up to the switch, the lower contact is attracted to the magnet and the upper contact is repelled, so the contacts split apart, opening the switch and breaking the circuit.
4.2.4 Closed Circuit Television (CCTV)
The purpose of CCTV in security solutions is to provide remote ‘eyes’ for security operators by providing live-action displays from a distance and/or to keep a video record of the spaces under monitoring.
There are two basic categories of CCTV systems: analogue CCTV systems and digital CCTV systems.
4.2.4.1 Analogue CCTV System
A typical analogue CCV system includes the basic components of camera, monitor, video switcher and video recorder. A camera is basic of any CCTV system. The camera creates the picture that will be transmitted to the monitoring or control position. However, CCTV is not just a simple camera-cable-monitor arrangement.
The basic function of a CCTV camera is to convert the physical scene viewed by the camera into an optical picture. By a focusing process, the scene is placed upon a special camera imaging tube which scans the imaged scene and breaks it down into various picture elements. These elements are then transmitted and converted into varying illumination levels that correspond to the video signal, which is ultimately converted into a visual scene on the system monitor. [13]
Figure 4. 5 Analogue CCTV camera
4.2.4.2 Digital CCTV (IP Surveillance)
An Internet Protocol camera, or IP camera, is a type of digital video camera commonly employed for surveillance, and which, unlike analogue cameras; it has an embedded video server having an IP address, capable of streaming the video (and sometimes, even audio) and can also send and receive data via a computer network and the internet.
Figure 4. 6 IP Camera
The CCTV systems should have the means of recording, such as using video cassete recorder (VCR), computer disc or other storage media, to maintain permanent records of whwt the cameras have seen. The recorded information could be used for future investigations or as evidence in prosecutions.
This type of camera offer many obvious advantages over the analogue systems, such as remote accessibillty, large storage capacity,simultaneous record and play back and the possibility of using the existing network and sharing the network with other building automation systems. Also, IP cameras can be connected directly to the IP network without pasing through the video server as in the case of analogue CCTV camera system.
4.3 Camera selections
Since there is an exixstng Local Area Network (LAN) in the hostel an IP camera was proposed and designed to be install in the hostel using an existing LAN which will allow the authorized person and security divisions to monitor and access the cameras from a remote locations over the Interne. Also, provide the option of recording video directly to a network video recorder (NVR).
These cameras should be Pan Tilt Zoom (PTZ) type, which they can be controlled through the DVR, remote viewing software, they can go up, down, left, and right, they also have zoom capability.
4.4 Locations of cameras
The locations of the cameras will be in different places of the building so as to have a total coverage of the building. The first set of two cameras were designed to be install in the ground floor one directly to the lifts side and the other one will covers reception facing the direction of non vegetarian dining hall near the manager’s office.
Figure 4. 7 Ground floor cameras
Four cameras to be install in the corridor of the building, the corridor is dived into three zones the first zone covers twelve rooms is called zone ‘A’, the middle zone (i.e. zone B) covers the highest number of rooms and the last zone i.e. zone ‘C’ also covers the same rooms with zone A.
One camera will be installed in zone ‘A’ facing East direction so that it will cover the whole zone. Two cameras will be installed in zone ‘B’ at each end edge of the zone in an opposite direction and one camera in the last zone in an opposite direction of the camera in zone A.
All the cameras have different IP address and can be program with camera software that connects to the network router.
Figure 4. 8 First floor cameras
4.6 Safety devices
Safety devices proposed in this work are those that detect the presence of unwanted harzads in the protected spaces by monitoring environmental changes such as rise in temperature above normal level, or changes associated with the combustion. These devices include fire detector, smoke detector, gas leak detector and water leakage detector to provde accurate measures against lost of lifves and properties..
4.6.1 Fire detector
A heat detctor detects fire by sensing changes in ambient temperature which is called Rate-of-Rise (ROR).
Rate-of-Rise (ROR) heat detectors operate on a rapid rise in element temperature of 12° to 15°F (6.7° to 8.3°C) increase per minute, irrespective of the starting temperature. This type of heat detector can operate at a lower temperature fire condition than would be possible if the threshold were fixed. It has two heat-sensitive thermocouples or thermistors. One thermocouple monitors heat transferred by convection or radiation. The other responds to ambient temperature. Detector responds when first’s temperature increases relative to the other.
Figure 4. 9 Fire detector
Rate of rise detectors may not respond to low energy release rates of slowly developing fires. To detect slowly developing fires combination detectors add a fixed temperature element that will ultimately respond when the fixed temperature element reaches the design threshold.
As the temperature of the surroundings rises above a prederminied threshold an alarm signal is triggered and send the signal to PLC in which the output will be seen in the monitoring room for an immediate action. Heat detector is selected for used in kitchen or utility areas where smoke detectors should not be installed, and the use of heat detector may not replace smoke detectors in student’s rooms, common rooms and corridor of the hostel.
4.6.2 Smoke detector
Smoke detectors detect smoke and issue signal to fire alarm systems. There are many different smoke detectors based on different mecahnisms and designs. Which include: ionization smoke detector, photoelectric smoke detector and air sampling smoke detctor.
4.6.2.1 Ionization smoke detector
An ionization smoke detctor contains a small amount of radioactiv material that ionizes the air between a positive and negative electrode. The conductance between the elctrode is measured. Introduction of smoke into the sampling chamber of the detector reduces the conductance between the electrodes. When the conductance falls below a pre-set threshold, the detector is triggered.
4.6.2.2 Photoelectric smoke detector
A key element of a photoelctric smoke detector is the light sensor. In a smoke detector, the light sensor is provided with the light source (e.g. Infrared LED) and lens to concentrate the light into a beam at an angle to the light sensor. In the absence of smoke, the light passes in front of the detector in a straight light.
When smoke enters the optical chamber across the path of the light beeam, some light is scattered by the smoke particles and directed at the sensor; thus the alarm is triggered.
Figure 4. 10 Smoke detector www.engineersgarage.com
4.6.2.3 Air sampling smoke detector
An air sampling smoke detector detects microscopic particles of smoke. Most air sampling detectors are work by actively drawing air through a network of small-bore pipes laid out above or below a ceiling in parallel runs covering a protected area. Small holes drilled into each pipe form a matrix of holes (sampling points), providing an even distribution across the pipe network.[13]
4.6.3 Gas leak detector
A gas detector is a device that detects the presence of gases in an area, often as part of a safety system. This type of equipment is used to detect a gas leak and interface with a control system so a process can be automatically shut down. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave.
This type of device is important because there are many gases that can be harmful to organic life, such as humans or animals.
www.securitysystemspune.com
Figure 4. 11 Gas leakage detector
4.6.4 Water leak detector
A water leak detector is an electronic device that is designed to detect the presence of water in a particular building and provide an alert in time to allow the prevention of water damages against properties. A common design is a small cable or device that lies flat on a floor or above some certain distance from the floor. It relies on the electrical conductivity of water to decrease the resistance across two contacts. The device then triggered an alarm to the control panel or station. These are useful in a normally occupied area near any infrastructure that has the potential to leak water, such as heating ventilation and air conditioning (HVAC), water supply pipes and water drainage.
4.7 Guide for safety devices selections
The purpose of this guide is to provide information concerning the proper selection and application of smoke, fire, and gas leakage detectors proposed. The guide outlines basic principles that should be considered before the selection. It presents operating characteristics of detectors and environmental factors, which may aid, delay, or prevent their operation. The national fire protection association (NFPA) has set up some standards for proper application, selection, installation and maintenance of automatic smoke, and fire detectors. The principal codes and standards have been reviewed before specifying these detectors. Some of these codes are listed below:
a. NFPA 101: Life Safety Code NFPA 101 specifies the requirements for smoke detection in both new and existing buildings depending on the type of occupancy.
b. NFPA 72: National Fire Alarm Code and Signaling Code NFPA 72 cover minimum performance, location, mounting, testing, and maintenance requirements of automatic fire detectors.
c. NFPA 90A: Standard for the Installation of Air Conditioning and Ventilating Systems
d. NFPA 92B: Smoke Control Systems in Malls, Atria, and Large Areas
e. NFPA 90A and 92B provide information for the use of smoke detectors in ducts of heating, ventilating, or air conditioning (HVAC) systems and smoke control systems. [20]
These are some of the standards followed for selection the proposed fire detectors for this designed to come with the proper and accurate design. Also, for each of the sensors to be used the manufactures data sheet guidelines should be strictly applied in addition to the NFPA standards.
Although smoke and fire detectors are based on simple concepts, certain design considerations need to be observed. They should produce an alarm signal when smoke is detected, but should minimize the impact of an unwanted signal which can arise from a variety of causes.
For example an ionization detector, dust and dirt can accumulate on the radioactive source and cause it to become more sensitive.
In a photoelectric detector, light from the light source may be reflected off the walls of the sensing chamber and be seen by the photosensitive device when no smoke is present. Insects, dirt, drywall dust, and other forms of contamination can accumulate in the sensing chamber and reflect light from the light source onto the photosensitive device.
Electrical transients and some kinds of radiated energy can affect the circuitry of both ionization and photoelectric smoke detectors and be interpreted by the electronic circuitry to be smoke, resulting in nuisance alarms.
LOCATIONS OF SENSORS AND WIRING TO PLC
6.1 Introduction
In this chapter we will discuss how these sensors smoke detector, fire detector, gas leakage detector and water leakage detector will be integrated in each room or structure in Mandela hostel for ensuring safety and security for the students and other staffs. We will also show how these sensors will be connected to programmable logic controller as remote terminal unit and finally to the master terminal units in manager’s office on the ground floor.
6.2 Smoke detectors locations
Because detector placement is critical to early warning functions, smoke and fire detectors should be installed in all areas of the protected premises. Total coverage as defined by NFPA 72 should include all student rooms, corridors, common rooms, kitchens and other places in the ground floor. Manufactures guide is also to be observed and followed accordingly.
6.3 Ground floor sensors locations
The ground floor of Mandela hostel has three building which include Non vegetarian dining hall, vegetarian dining hall, reception and manager’s office. All
Figure 6. 1 Locations of sensors in the ground floor
KEY:
D1 ————–Manager’s office door
D2—————Non vegetarian dining hall door
D3—————Dining hall kitchen door
D5—————Dining hall wash room door
Since all the proposed smoke and fire detectors are ceiling mounting, the spaces between them is followed according to the NFPA and manufactures guide lines.
Figure 6. 2 Parallel connections of sensors
The distance designed between each detector is 3m from the wall close to it.
6.3 Locations of Sensors in Students rooms
Since the rooms in the entire floors are and same and identical the figure below shows the suitable locations of sensors in a room for the first floor which represents the remaining floors.
et
Figure 6. 3 Sensor locations in students’ rooms
D1 stand for room door and all the dimensions are in meters (m)
Safety sensors i.e. smoke; fire and water leak detectors are connected in parallel and same connections throughout the design also, same standard is applied.
Figure 6. 4 Common room sensor locations
6.4 Programmable Logic Controller
Programmable controllers are often defined as miniature industrial computers that contain hardware and software used to perform control functions. A controller consists of two basic sections: the central processing unit (CPU) and the input/output interface system. The CPU, which controls all system activity, can further be broken down into the processor and memory system. The input/output system is physically connected to field devices (e.g., switches, sensors, etc.) and provides the interface between the CPU and the information providers (inputs) and controllable devices (outputs). To operate, the CPU “reads” input data from connected field devices through the use of its input interfaces, and then “executes” or performs the control program that has been stored in its memory system. Programs are typically created in ladder logic, a language that closely resembles a relay-based wiring schematic, and are entered into the CPU’s memory prior to operation. Finally, based on the program, the PLC “writes” or updates output devices via the output interfaces. This process, also known as scanning, typically continues in the same sequence without interruption, and changes only when a change is made to the control program.
6.4.1 PLC Selection
To select the best PLC suitable for any design, the following conditions must be observed:
a. Proposed System: Determine whether your system is new or existing: Will your system be installed from scratch or are there existing products already installed? The rest of your system will need to be compatible with new components.
b. Environmental Issues: Consider any environmental issues that will affect your application (temperature, dust, vibration, codes specific to your facility, etc.).
c. Discrete Devices: Determine how many discrete devices your system will have. Which types (AC, DC, etc.) are needed?
d. Analog Devices: Determine how many analog devices your system will have. Which types (voltage, current, temperature, etc.) are needed?
e. Determine whether your system will require any specialty features: Will your application require high-speed counting or positioning? What about a real-time clock or other specialty feature?
f. Determine the type of CPU you will need: How much memory wills your system require? How many devices will your system have (determines data memory)? How large is your program, and what types of instructions will your program include (determines program memory)? How fast a scan time do you need?
g. Determine where your I/O will be located: Will your system require only local I/O, or both local and remote I/O locations?
h. Determine your communication requirements: Will your system be communicating to other networks, systems or field devices?
i. Determine your programming requirements: Does your application require only traditional programming instructions, or are special instructions necessary? [21]
The sensors outputs are connected to the PLC inputs placed closed to the distribution box. For every floor we have three PLCs to be placed closed to each of the three available distribution boxes.
Figure 6. 5 Sensors connection to PLC
Safety and security sensors are connected to PLC were smoke, fire, and water leak detectors are connected in parallels so that one input of the PLC is used to customize the number of inputs to be used. The output of the PLC is monitored on the SCADA in the control room. Ethernet port is used for Ethernet connection as discussed in the next chapter.