Introduction
Buildings are becoming more and more advanced and the demands on building automation systems are increasing. A modern building is expected to provide conditions for a number of services with high security, energy efficiency safety and comport. For a building with complex requirements due to the activity, such as a hospital, schools and school hostels, the services provided are even more advanced and the requirements on them are higher. Many of these services benefit from communicating with each other, sharing functions and being monitored together from a centralized station. To provide all these building services in an efficient way, a more or less advanced building automation system is required. The advantages of using an advanced building automation system are:
a. Monitoring of several devices from one place
b. Sharing of the same alarm and network
1.1 What is Building Automation?
Building Automation System (BAS) are centralize network of hardware and software components used to monitor and control the electrical devices for safety, security and comport in a building, and also, used for energy savings such as light control, Heating, Ventilation and Air Conditioning (HVAC).
When defining building automation systems, it is advantageous to state that, the system comprises of field devices level, automation level and field network.
1.2 Field devices level
The Field devices level consists of all devices that physically control or detect the building functions. They are devices like actuators, motion sensors, smoke detectors, glass break detector, valves, dampers, fans, card readers, motors, sprinklers, light switches, hospital specific equipment etc. Most of these devices do not have any “intelligence” of their own.
They either send their status or react to control signals. In the very most basic system, Field level devices are not connected to anything and are controlled manually. For simple automatic control, a control device can be connected to a sensor for example a light switch connected to a motion sensor.
1.3 Automation level
The Automation level includes all the advanced controllers that controls and regulates the Field level devices in real time. Today, these controllers are usually digitals and based on microprocessors. This makes it possible to freely program them with any other logic control or combination of logic controls. The controllers can be divided into two categories:
a. PLC – Programmable Logic Controller and
b. RTU – Remote Terminal Unit
A PLC works similar to a modern computer. It can be feely programmed to act on any number of input data and control any number of output data as long as it has sufficient processing power and ports. A PLC can often be expanded with racks containing I/O ports connected to one of the PLCs internal buses. There are also more advanced PLCs, often called Soft-PLC. They run on a more advanced operating system (like Windows) and can be connected to a display and a keyboard. A RTU usually has less processing power and fewer ports then a PLC.
This is because a RTU is built for a specific task and is dimensioned accordingly. It is common that a RTU is shipped pre-programmed so that the user only has to adjust it. In most other aspects are PLCs and RTUs similar and there is not a strict boundary between the classifications. It is common that the manufacturer of a unit includes a control system containing a RTU, a Field network and all Field level devices commonly referred to as a entity unit with integrated control.
In the simplest case a PLC or RTU works as a standalone unit with no interaction with other PLCs, RTU or equipment in the Management level. In order to communicate, a PLC or RTU can either be connected to the Primary network and communicate through a SCADA system or CCS, Central Control Station or have a small local peer-to- peer network in which a limited amount of PLCs or RTUs can communicate.
These solutions work fine for many applications, but for more advanced building services systems a more advanced control system is usually desired. This is usually achieved by connecting the Field level devices to a more advanced controller such as Programmable Logic Controller (PLC) in the Automation level through a Field network. The Field level devices then act, as slaves while their Automation level controllers are masters. There are also Field level devices that connect to a building automation system in other ways. For example an outside weather station could be connected to the Primary network, either directly or through a gate way.
1.4 Field network
The Field network is the network that connects the Field level sensors with the Automation level. The main purpose with this network is to connect the actuators, sensors and other Field level devices to a Programmable Logic Controller (PLC), or Remote Terminal Unit (RTU) in the Automation level. The physical connection between the two levels can be of four various types.
a. Wired network
b. Bus network
c. Wireless network
One or more of these four types will be the backbone of a Field network. A building automation system usually contains several Field networks.
1.4.1 Wired network
If the devices in the Field level are connected by hard wiring, each device is connected by an individual cable to an individual port on an Automation level device. What type of signals that is sent over the Field network depend on what devices that form the system. For example a common way to control a valve is to supply a voltage between 0 V and 10 V.
This is an analogue control signal that tells the valve what position it should have. A more advanced example could be an outside weather station hard wired to a PLC via some sort of data cable. The signals sent in this example consist of digital data. Hard wiring is usually a satisfying solution for systems with a limited number of connections.
1.4.2 Field bus network
Another solution is to connect the Field level devices through one or several Field busses. A Field bus usually consists of twisted pair copper cables for communication. Power supply can either be connected separately to the devices or included in an extra wire in the bus cable. The origin of the field bus was to replace any point-to-point links between the field devices (Field Devices are simply the Sensors and Actuators of the plant) and their controllers (like PLC’s, CNC’s …etc.) by a digital single link on which all the information is transmitted serially and multiplexed in time. We will see that the field bus transfers, in most cases, this information in small-sized packets in serial manner.
Choosing the serial transmission has many advantages in comparison with other kinds of transmission like parallel transmission. For instance, the sequential or serial transmission reduces the total required number of the connecting lines over greater distances than that of the point-to-point or even parallel transmissions. A set of rules must be defined in order to accomplish data transfer between the units along the bus. This set of rules is called Communication Protocol or just the Protocol. This is unlike the case of the ordinary point-to-point transmission where any two connected entities send and receive data from each other whenever the data is available. The protocol is responsible for two important rules on the bus, the mechanism that any unit can acquire or seize the bus (from the network terminology this means the way of Medium Access), and the synchronization between those multi-units on the bus.
The Field bus can be compared with a Local Area Network. In a Field bus no switches are needed in intersections where the devices connect to the main cable. Local Area Network on the other hand has a bit rate of about 100-1000 megabit per second. This means that if there would not be any switches to split and isolate the communication between two nodes, the network would have a constant overflow of reflecting signals.
Due to the lack of switches, all devices along the bus receive messages sent over the cable but only the addressed devices react to it. Common bit rates for these types of networks are around 1-40 kilobit per second, less than a thousandth of a common Ethernet network. This is enough for most appliances since a common message only consists of a couple of bytes. [1]
The numbers of components that can be connected in one bus vary from tens to thousands depending on the protocol used, cable length and connection types.
1.4.3 Wireless network
The far most common wireless communication technology for Field networks is radio frequency in the middle frequency band (868 MHz). Data is transmitted by modeling frequency, phase or amplitude of the radio waves, ZVEI (2006). Common range for a transmitter is around 30 m horizontally in a building with lightweight partition walls made of for example timber and gypsum. The range can be greatly reduced if the walls contain metal, are made of concrete or if there are other special circumstances. Amplifiers can be used to extend the range; often they are included in the transmitters in the Field level devices.[1]
1.5 Objective of Dissertation work
The main objective of this dissertation is to design a building automation system for safety and security in Mandela hostel of Sharda University sing appropriate sensor devices in student’s rooms, corridors, dining halls, attached offices to ensure the safety and security of the students, properties and other staffs leaving in the hostel against unauthorized entry and fire out breakage.
The needs of the security and safety systems in Mandela hostel arise due to the increase in the number of students and staffs leaving in the hostel in which some unauthorized people may have the chance of entering the premises without permission. This will help the security operators in the hostel for proper monitoring the activities within the hostel.
1.6 Layout of the Dissertation work
Chapter 1: The first chapter is an introduction to building automation systems where we defined what is building automation? We also discussed the different levels of building automation. The objective of dissertation and layout of the dissertation is also presented.
Chapter 2: In this chapter the review of works done related to this dissertation is presented and their different technologies has been analyzed and effectively applied in the proposed design.
Chapter 3: The third chapter of this dissertation shows the detail diagrams of structures in the building.
Chapter 4: The proposed safety and security devices used in the design are described, it also covers the discussion CCTV cameras to be installed and the selected type is proposed in this chapter.
Chapter 5: This chapter gives the introduction of access control and the different technologies of access control we also discussed the type of access control technology to be used for Mandela hostel.
Chapter 6: We discussed the suitable sensors locations and their wiring to PLC in this chapter.
Chapter 7: This chapter contains the PLC and SCADA programming.
Chapter 8: In this chapter the conclusion and future scope of the work is presented.