Безопасность жизнедеятельности. Теория и практика

ɍȾɄ 614.8 
ȻȻɄ 68.9 
ɋ34 
 
Ɋɟɰɟɧɡɟɧɬɵ: 
ɞ. ɬ. ɧ., ɩɪɨɮɟɫɫɨɪ, ɡɚɜ. ɤɚɮɟɞɪɨɣ ȻɀȾ ɉɟɪɦɫɤɨɝɨ ɧɚɰɢɨɧɚɥɶɧɨɝɨ ɢɫɫɥɟɞɨɜɚɬɟɥɶɫɤɨɝɨ  
ɩɨɥɢɬɟɯɧɢɱɟɫɤɨɝɨ ɭɧɢɜɟɪɫɢɬɟɬɚ (ɉɇɂɉɍ) ɑɺɪɧɵɣ Ʉ. Ⱥ.; 
ɤ. ɩ. ɧ., ɞɨɰɟɧɬ ɤɚɮɟɞɪɵ ɢɧɨɫɬɪɚɧɧɵɯ ɹɡɵɤɨɜ ɘɠɧɨ-ɍɪɚɥɶɫɤɨɝɨ ɝɨɫɭɞɚɪɫɬɜɟɧɧɨɝɨ  
ɦɟɞɢɰɢɧɫɤɨɝɨ ɭɧɢɜɟɪɫɢɬɟɬɚ (ɘɍȽɆɍ) Ȼɨɹɥɶɫɤɚɹ Ɍ. Ⱥ. 
 
Reviewers: 
Doctor of Technical Sciences, Professor, Head of the Department of the Belarusian Railways  
of Perm National Research Polytechnic University Cherny K. A.; 
Candidate of Pedagogical Sciences, Associate Professor of the Department of Foreign Languages  
of the South Ural State Medical University Boyalskaya T. A. 
 
 
 
ɋɢɞɨɪɨɜ, Ⱥ. ɂ. 
ɋ34  
Ȼɟɡɨɩɚɫɧɨɫɬɶ ɠɢɡɧɟɞɟɹɬɟɥɶɧɨɫɬɢ. Ɍɟɨɪɢɹ ɢ ɩɪɚɤɬɢɤɚ : ɭɱɟɛɧɨɟ ɩɨɫɨɛɢɟ / 
Ⱥ. ɂ. ɋɢɞɨɪɨɜ, Ɉ. Ⱥ. ɏɚɧɠɢɧɚ. – Ɇɨɫɤɜɚ ; ȼɨɥɨɝɞɚ : ɂɧɮɪɚ-ɂɧɠɟɧɟɪɢɹ, 
2024. – 108 ɫ. : ɢɥ., ɬɚɛɥ. 
ISBN 978-5-9729-1998-7 
 
ɍɱɟɛɧɨɟ ɩɨɫɨɛɢɟ ɩɪɟɞɧɚɡɧɚɱɟɧɨ ɞɥɹ ɫɬɭɞɟɧɬɨɜ, ɦɚɝɢɫɬɪɚɧɬɨɜ, ɚɫɩɢɪɚɧɬɨɜ, ɢɡɭɱɚɸɳɢɯ ɚɧɝɥɢɣɫɤɢɣ ɹɡɵɤ ɢ ɞɥɹ ɢɡɭɱɟɧɢɹ ɛɟɡɨɩɚɫɧɨɫɬɢ ɠɢɡɧɟɞɟɹɬɟɥɶɧɨɫɬɢ ɤɚɤ ɭɱɟɛɧɨɣ 
ɞɢɫɰɢɩɥɢɧɵ. ȼ ɭɱɟɛɧɨɦ ɩɨɫɨɛɢɢ ɫɨɞɟɪɠɚɬɫɹ ɬɟɨɪɟɬɢɱɟɫɤɢɟ ɨɫɧɨɜɵ ɛɟɡɨɩɚɫɧɨɫɬɢ ɠɢɡɧɟɞɟɹɬɟɥɶɧɨɫɬɢ, ɪɚɫɫɦɚɬɪɢɜɚɸɬɫɹ ɭɫɥɨɜɢɹ, ɨɩɪɟɞɟɥɹɸɳɢɟ ɨɬɫɭɬɫɬɜɢɟ ɜɪɟɞɧɨɫɬɢ ɞɥɹ 
ɨɪɝɚɧɢɡɦɚ ɱɟɥɨɜɟɤɚ, ɜɨɡɞɟɣɫɬɜɢɟ ɷɥɟɤɬɪɢɱɟɫɤɨɝɨ ɬɨɤɚ ɧɚ ɱɟɥɨɜɟɤɚ. ɉɟɪɟɱɢɫɥɟɧɵ ɦɟɪɵ 
ɡɚɳɢɬɵ ɨɬ ɜɪɟɞɨɧɨɫɧɵɯ ɢ ɨɩɚɫɧɵɯ ɮɚɤɬɨɪɨɜ. Ɍɚɤɠɟ ɤɧɢɝɚ ɫɨɞɟɪɠɢɬ ɫɛɨɪɧɢɤ ɡɚɞɚɧɢɣ. 
ɉɨɫɨɛɢɟ ɦɨɠɟɬ ɛɵɬɶ ɢɫɩɨɥɶɡɨɜɚɧɨ ɞɥɹ ɩɟɪɟɜɨɞɚ ɬɟɯɧɢɱɟɫɤɢɯ ɢ ɧɚɭɱɧɵɯ ɬɟɤɫɬɨɜ ɜ 
ɪɚɦɤɚɯ ɞɢɫɰɢɩɥɢɧɵ «ɂɧɨɫɬɪɚɧɧɵɣ ɹɡɵɤ ɞɥɹ ɩɪɨɮɟɫɫɢɨɧɚɥɶɧɨɝɨ ɨɛɳɟɧɢɹ». 
 
The training manual is intended for students, undergraduates, postgraduates studying 
English and in the course of studying Life Safety as an academic discipline. It contains theoretical framework of life safety, conditions are considered that determine the absence of 
harmfulness to the human body, the effect of an electric current on a person. Measures are 
provided to protect against harmful and dangerous factors. It also contains collection of 
Tasks. 
The manual can be used for translation of technical and scientific texts within the 
framework of the discipline “Foreign language for professional communicatiɨn”. 
 
ɍȾɄ 614.8 
ȻȻɄ 68.9 
 
ISBN 978-5-9729-1998-7 
© ɋɢɞɨɪɨɜ Ⱥ. ɂ., ɏɚɧɠɢɧɚ Ɉ. Ⱥ., 2024 
 
© ɂɡɞɚɬɟɥɶɫɬɜɨ «ɂɧɮɪɚ-ɂɧɠɟɧɟɪɢɹ», 2024 
 
© Ɉɮɨɪɦɥɟɧɢɟ. ɂɡɞɚɬɟɥɶɫɬɜɨ «ɂɧɮɪɚ-ɂɧɠɟɧɟɪɢɹ», 2024 
2 

CONTENTS 
 
 
INTRODUCTION 
............................................................................................... 4 
1. Theoretical basis of life safety ........................................................................ 6 
1.1. “Human – technology – environment” system: general description ........... 6 
1.2. “Human – technology – environment” system model ................................. 6 
1.3. The effectiveness of the security system 
...................................................... 9 
1.4. The cost of security system ........................................................................ 11 
1.5. Danger and it’s sources. Quantitative characteristic 
               of the danger. The concept of acceptable risk 
............................................ 11 
1.6. The concept of security. Security Systems. Principles and methods  
               of safety ensuring ....................................................................................... 16 
2. WORKING CONDITIONS .......................................................................... 19 
2.1. The microclimate of industrial premises 
.................................................... 19 
2.2. Harmful substances .................................................................................... 27 
3. MANUFACTURING ILLUMINATION ..................................................... 39 
3.1. Types of manufacturing illumination 
......................................................... 39 
3.2. Sources of artificial lighting 
....................................................................... 44 
3.3. Luminaire ................................................................................................... 51 
4. NOISE OF ELECTRICAL MACHINES ..................................................... 53 
4.1. An effect of the noise on the body ............................................................. 53 
4.2. Noise of rotating electrical machines 
......................................................... 56 
4.3. Noise of transformers ................................................................................. 59 
5. THE EFFECT OF AN ELECTRIC CURRENT ON A HUMAN BODY 
...... 
64 
5.1. Modern ideas about the mechanism of electrical injuries 
.......................... 64 
5.2. Electrical parameters of the human body 
................................................... 66 
5.2.1. General characteristics and assessments ................................................. 66 
5.2.2. Threshold Voltages ................................................................................. 67 
5.2.3. Threshold currents 
................................................................................... 68 
6. TECHNICAL METHODS OF ENSURING THE SAFETY  
            OF OPERATION  OF ELECTRICAL INSTALLATIONS ......................... 71 
6.1. Safety analysis of electrical installations ................................................... 71 
6.2. Protective grounding .................................................................................. 77 
6.3. Zeroing out ................................................................................................. 78 
6.4. Control and prevention of insulation damage ............................................ 79 
7. ENSURING FIRE SAFETY IN POWER-SUPPLY SYSTEMS ................. 82 
7.1. Ensuring fire safety at the ODD (open distribution device) ...................... 82 
7.2. Fire safety of cable rooms .......................................................................... 84 
8. COLLECTION OF TASKS 
.......................................................................... 88 
8.1. Risk analysis of electric shock in networks with different neutral  
               conditions ................................................................................................... 88 
8.2. Tasks 
........................................................................................................... 92 
APPENDIX ....................................................................................................... 98 
BIBLIOGRAPHIC LIST ................................................................................ 104 
3 

INTRODUCTION 
 
The word “Safety” seems to be familiar to everyone. Safety, as the absence of 
danger, parents convince their children, there is a school subject called “Principles of 
personal and social safety” (Life Safety), but this does not reduce the number of injuries and deaths. Thousands of children die and get injured in games, everyday life, 
kindergartens, and schools. Thousands of working age people die or get injured in the 
streets, in cars, at houses, on vocation, during work activities. Almost all of them, 
however, are warned about dangers, but for some reasons, they sincerely think that 
nothing can happen to them. However, this is exactly what happens. The reason of it 
is the person himself. This person projects and produces different technical devices 
that are insufficient safe, this person organizes technological process, in which safety 
requirements are not sufficiently taken into account, this person exploits equipment 
and does not observe safety rules. All of new over different people, for sure lure still 
people. 
Every person lives in the world of danger. Stair steps, open windows, appliances, gas device system in the kitchen – all this surrounds most people from childhood. 
Bicycle, motor bicycle, car, public transport – all these things surround us during all 
our life. Various equipment accompanies a person in his working activity with its 
special dangers. How can a person avoid exposure to these dangers?  
“Health and safety” “life safety” as the academic subject serves precisely to 
study consistent pattern of appearance, development, prevention of dangers and also 
is for practical realization of dangers prevention.  
The descriptive material at the dawn of modern humanity contains characteristics of floods, earthquakes, volcanic eruptions, droughts, epidemics and the behavior 
of people that managed to survive in these situations. Chronicles, religious treatises, 
other sources of literature make a point out those actions that help to prevent diseases 
and the deaths of people during natural disasters. 
In the latest millennium experimental proof of various dangers appeared, because of modern science development – Riemann death from lightning, chemical poisonings of people, workers’ injuries on the woods and metal working machines, on 
knitting looms, miners’ diseases, burns of people working with steam engine machines, steam boiler explosions, etc. All this accrued by experience, human victims, 
disability and so on. Regretfully, the humanity did not have some other ways, as discovery of something new is the beginning of uncertainty. The first works with radioactive radium were held with bare hands, without any protection. The protection necessity was explored long after when a lot of people suffered from radiation disease. 
Facts accumulation has always obligated the scientists who have analyzed these 
facts to establish patterns of the appearance and development of danger, and also to 
find the ways to prevent them and to protect from them. 
All sorts of individual and collective remedies have a meaning as protection to 
keep All kinds of individual and collective protective equipment allow to accomplish 
technological operations in conditions of significant dangers, saving the workers’ 
lives. A lot of things have been done to prevent professional diseases and to reduce 
the results of their consequences. However, there is no scientific approach to the sub4 

stantiation of personal protection measures from equipment in the development stage, 
testing, and exploitations.  
It was offered to use a method similar to reliability. Indeed, as in reliability, an 
injury is an accident. A person is an element of the “person- technology” system. A 
person’s injury is an element’s refusal. So it was attractive to many people that it is 
possible to speak about safety with, for example, 0,95 of probability.  A little detail is 
forgotten, firstly, we can’t carry out a test to refusal with a person taking part in it, 
secondly, figure 0,95 shows that in 5 cases from 100 a person will have an injury or 
will die. Will we find any people that want to work with the equipment on which  
5 people must die during 3 months? 
Nowadays the biggest expansion gets the “risky” method, the main contents of 
which consists of risk assessment of getting injured or dying. After rejecting the reliability method, the theory remains under the probable assessment of getting injured 
and dying with disadvantages that have been already pointed out. The most important 
of them is that there is no possibility to set quantitative requirements for equipment 
safety, the workplace, and technological process to verify their implementation at the 
design, manufacturing, testing, and operation stages. 
“Health and safety” academic discipline is synthetic applied discipline, basing 
on common principles of physics, on knowledge of mathematics, physics, chemistry, 
biology, medicine, ecology, meteorology, geology, geophysics, volcanology, seismology, and other disciplines. The knowledge of mechanics, structural resistance, 
stability theory, electrical technology, hydrodynamics, acoustics, oscillation theory, 
electromagnetic field theory, combustion and explosion theory and other applied disciplines let identify the influence of dangerous and harmful factors on the human 
body and develop methods and means of personal protection from them.    
With the using of other scientific achievements, “Health and safety” has its own 
object and subject matter. The object matter of “Health and safety” is a system “human-technology-environment” and a subject matter is the regularity of dangers appearance, development and methods and protective equipment from dangerous, and 
harmful factors. 
Consequently, it is necessary to find regularities of dangers appearance and development and protection from them in simple, understandable and measurable dangers parameters, their changes, transformation and mutual influence. 
As safety we understand lack of danger for a person (V.I. Dahl).  
However, a person can not be in abstract space. He is always connected with 
technology and natural environment, in other words he is in the “human-technologyenvironment” (HTE) system. 
5 

1. THEORETICAL BASIS OF LIFE SAFETY 
 
1.1. “Human – technology – environment” system:  
general description 
 
People are never alone; a certain environment and technical devices always surround them. Furthermore, they are constantly interacting with technologies and environment using them for their own purpose. All these allow to define the system as “a 
set of interrelated elements, which interaction is aimed at achieving certain goals”. 
These goals are set by man. Achievement of the goals requires appropriate technology and means. Human interaction with technology and environment is a certain process – therefore, it is a system-forming factor. This process is controlled by man and 
always accompanied by the emergence of the relevant information. 
This is the most common description of a model that defines “human – technology – environment” system that is necessary for the analysis and synthesis of the 
safety system. As we know, people operate with dangerous technology devices all the 
time. They do it in different locations (indoors, outdoors)that have a lot of natural 
factors (low temperature, rain, snow storms, rock falls, mudflow, flood, earthquakes) 
that either increase or decrease various effects from that technology. People need 
technology in order to achieve their goals. Human-technology interaction – is a process that can involve only one person in his workplace as well as several people in 
different places. During this interaction both people and technology could be dislocated. Dislocation equipment and people can change the environment. 
The technological process is accompanied by the creation of informationinstrument readings, creation of sound, vibratory and electromagnetic fields, temperature, etc.  
This information makes possible to manage the system of safety. On the basis of 
information on the state of security, measures are planned to improve it, which are 
provided with the necessary information, human, material resources, are promptly 
managed by the relevant authorities, and the results of improving security are recorded and analyzed. 
Thus, the definition of a safety system overlaps the requirements of system elements selected from general variety. The system of safety can be considered as a 
complex system that needs to be studied and analyzed. 
 
1.2. “Human – technology – environment” system model 
 
Analysis and synthesis of the safety system are only possible with its mathematical description, i.e. using the models However, modeling a security system is extremely difficult, since the variety of elements of the system is very difficult in describing the elements, their interconnections and interactions. Therefore, it is necessary to use mathematical apparatus, which has a high degree of abstraction. In this 
case: 
 
6 

L – amount of people; 
T – amount of technology; 
E – amount of environmental elements; 
J – amount of information; 
Y – amount of control elements. 
R – the relationship between the elements is defined by the relations R, which 
can be understood as functional features, preferences, choices and other interactions. 
Thus we have: 
 
LR1T, 
TR5L, 
ER9L, 
JR13L, 
YR17L, 
(1.1)
LR2E, 
TR6E, 
ER10T, 
JR14T, 
YR18T, 
LR3J, 
TR7J, 
ER11J, 
JR15E, 
YR19E, 
LR4Y, 
TR8Y, 
ER12Y, 
JR16Y, 
YR20J. 
 
The system of equations (1.1) is a model of a security system, if of all human 
properties, only those that are relevant to safety are considered, of all the properties 
of technical devices, only those that are associated with hazards or human safety are 
considered, of all properties of nature only those that pose a danger to humans are 
considered, and finally, information only on the dangers and safety of people. Management is initially formulated as a safety management. 
As for as the abstract description (1.1) does not allow us to directly analyze and 
synthesize safety systems, we make the following transformations. As is known, binary relations can be decomposed into more complex ones with the introduction of an 
additional variable, called the state C, if only the sets connected by a relation can be 
divided by some criterion into at least 2 subsets. In our case, such a division is quite 
possible, for example, on the basis of danger: “dangerous – not dangerous”. In this 
case the system (1.1) is transformed in the following manner: 
 
LRଵ
ଵൣC୐
୘, Tଵ൧, C୐
୘Rଵ
ଶTଶ; 
TRହ
ଵൣC୘
୐, Lଵ൧, C୘
୐Rହ
ଶLଶ; 
ERଽ
ଵൣC୉
୐, Lଵ൧, C୉
୐Rଽ
ଶLଶ; 
LRଶ
ଵൣC୐
୉, Eଵ൧, C୐
୉Rଶ
ଶEଶ; 
TR଺
ଵൣC୘
୉, Eଵ൧, C୘
୉R଺
ଶEଶ; 
ERଵ଴
ଵൣC୉
୘, Tଵ൧, C୉
୘Rଵ଴
ଶTଶ; 
LRଷ
ଵൣC୐
୎, Jଵ൧, C୐
୎Rଷ
ଶJଶ; 
TR଻
ଵൣC୘
୎, Jଵ൧, C୘
୎R଻
ଶJଶ; 
ERଵଵ
ଵൣC୉
୎, Jଵ൧, C୉
୎Rଵଵ
ଶJଶ; 
LRସ
ଵൣC୐
ଢ଼, Yଵ൧, C୐
ଢ଼Rସ
ଶYଶ; 
TR଼
ଵൣC୘
ଢ଼, Yଵ൧, C୘
ଢ଼R଼
ଶYଶ; 
ERଵଶ
ଵൣC୉
ଢ଼, Yଵ൧, C୉
ଢ଼Rଵଶ
ଶYଶ; 
 
JRଵଷ
ଵൣC୎
୐, Lଵ൧, C୎
୐Rଵଷ
ଶLଶ;   
YRଵ଻
ଵൣCଢ଼
୐, Lଵ൧, Cଢ଼
୐Rଵ଻
ଶLଶ;   
 
JRଵସ
ଵൣC୎
୘, Tଵ൧, C୎
୘Rଵସ
ଶTଶ; 
YRଵ଼
ଵൣCଢ଼
୘, Tଵ൧, Cଢ଼
୘Rଵ଼
ଶTଶ; 
(1.2) 
JRଵହ
ଵൣC୎
୉, Eଵ൧, C୎
୉Rଵହ
ଶEଶ; 
YRଵଽ
ଵൣCଢ଼
୉, Eଵ൧, Cଢ଼
୉Rଵଽ
ଶEଶ; 
JRଵ଺
ଵൣC୎
ଢ଼, Yଵ൧, C୎
ଢ଼Rଵ଺
ଶYଶ; 
YRଶ଴
ଵൣCଢ଼
୎, Jଵ൧, Cଢ଼
୎Rଶ଴
ଶJଶ.   
 
 
Based on (1.2) it is possible to determine condition (C) for all elements of the 
safety system:  
 
C୐ൌFଵൣሼS୐ሽ, C୐
୘ , C୐
୉, C୐
୎ , C୐
ଢ଼൧, 
(1.3)
 
7 

C୘ൌFଶൣሼS୘ሽ, C୘
୐ , C୘
୉, C୘
୎ , C୘
ଢ଼൧, 
(1.4)
 
C୉ൌFଷൣሼS୉ሽ, C୉
୐ , C୉
୘, C୉
୎ , C୉
ଢ଼൧, 
(1.5)
 
C୎ൌFସൣ൛S୎ൟ, C୎
୐ , C୎
୘, C୎
୉ , C୎
ଢ଼൧, 
(1.6)
 
Cଢ଼ൌFହൣሼSଢ଼ሽ, Cଢ଼
୐ , Cଢ଼
୘, Cଢ଼
୉ , Cଢ଼
୎൧, 
(1.7)
 
Cு்ாൌF଺ൣሼSୗୗሽ, ʠ୐, C୘, C୉, C୎, Cଢ଼൧. 
(1.8)
 
Man’s condition depends on its own properties (health, education, discipline, 
accuracy of actions, mindfulness) as well as on the safety of technology and environment and the information that is given to people, how effective is security management. 
The quality of technology depends on the personal safety of the technician, on 
how safe people work on the technology, how much the environment affects the security of the technology, how much information about the technology is disseminated 
among the maintenance personnel, how the security management system affects the 
technology. 
The state of the environment depends on the intrinsic properties of the environment – air dispersion, dissolution in water, congestion in lowlands, etc., on the actions of people to change the safe state of the environment, on how technology 
changes the safe state of the environment, from information about the security of the 
environment, from the impact of the control system on the environment. 
The condition of the information also depends on its own properties (complete, 
timeliness and reliability), as well as the influence of people on information, the condition of technology issuing information, and the influence of management on information. 
The condition of security management depends on one's own propertiesmanagement effectiveness and efficiency, as well as on how people are prepared and 
relate to security controls, how the environment can be influenced, how information 
makes it possible to adopt the optimal security management solution. 
The condition of the safety system (“human – technology – environment”) determines by system properties (efficiency, accuracy) and condition of system elements. 
The cost of the safety system is obvious and determined by funds invested in the 
designing, testing, manufacturing and installation of such system. The effectiveness 
of the system – the degree of achievement of the goal and requires a separate consideration. 
The condition of a system can be “safe” Cு்ா
ௌ
: when the sources of danger cannot lead to injury, death or disease of a person. If some sources can lead to human 
health deterioration or cause death or disease, but there are no sufficient conditions, 
i.e. other parameters do not allow damage to a person, the condition is “dangerous 
8 

situation”  Cு்ா
஽ௌ. The condition in which trauma, death or disease of a person occurs 
can be called the state of an “accident”  Cு்ா
஺
 (Fig. 1.1). 
ܥு்ா
஺
 
ܥு்ா
஽ௌ 
ܥு்ா
ௌ
 
 
Fig. 1.1. Graph of system transition  
from one condition to another 
 
Originally the system is in the condition ܥு்ா
ௌ
. During the process of work parameters of the sources of danger change and system can transform into condition 
ܥு்ா
஽ௌ. A transition into the state ܥு்ா
஺
is possible only from the condition ܥு்ா
஽ௌ.The 
duration of the ܥு்ா
஽ௌ can vary from years to milliseconds, but the system must be in a 
dangerous situation. From the state ܥு்ா
஽ௌ the system can transit into ܥு்ா
ௌ
 or ܥு்ா
஺
. 
After the ܥு்ா
஺
 transition ends – there can be only another system. 
 
1.3. The effectiveness of the security system 
 
The effectiveness of the securitysystem depends on the formulation of its purpose. Apparently, there can be no other aim, except for exclusions of injuries, death, 
diseases. In this regard, a criterion for the effectiveness of the security system should 
be a criterion that assesses the absence of injuries, deaths or occupational diseases. 
Consequently, it must determine the possibility of the HTE system to avoid ܥு்ௌ
஺
. The 
possibility of getting or not getting into any state can be estimated by probability – 
 
 
 P୅ሺtሻ or [1 െP୅ሺtሻ] = Q஺ሺtሻ. 
(1.9) 
 
It is clear that the requirements for the system of this indicator cannot be specified. Existing systems can only be evaluated and compared. 
From Fig. 1.1. the probability of the HTE system getting into ʠு்ா
஺
 can be determined as follows. 
ʠு்ா
ௌ
 will be the state “1”; ʠு்ா
஽ௌ as – “2”, and ʠு்ா
஺
 –  “3”. 
Then: Ƚଵଶ – is probability of transition from “1” to “2”, Ƚଶଵ – probability of 
transition from “2” to “1”, and Ƚଶଷ – probability of transition from “2” to “3” 
(Fig. 1.2). 
9 

Ƚଶଷ 
Ƚଶଵ 
2 
1 
Ƚଵଶ 
Fig. 1.2. Probability transition graph 
 
It is advisable to consider such processes using the apparatus of semi-Markov 
random processes. The semi-Markov process is used because there is no confidence 
in the exponentially of the distribution law of random events of transition from one 
state to another. 
The system of algebraic equations of probabilities of getting into each state and 
the normalizing equation can be written as follows: 
 
P
ଷ= P
ଶή Ƚଶଷ 
(1.10)
P
ଶ= P
ଵή ȽଶଵെP
ଶή ȽଶଷെP
ଶή Ƚଶଵ 
P
ଵ= P
ଶή ȽଶଵെP
ଵή Ƚଵଶ 
P
ଵ+ P
ଶ+ P
ଷ= 1. 
 
Substituting P
ଶ in P
ଵ and then in P
ଷ we get: 
 
. 
 (1.11)
P
ଷ= P
ଵή ሺȽଵଶή Ƚଶଷሻ
1 + Ƚଶଵ+ Ƚଶଷ
 
The probability of HTE system to get or avoid the condition of the accident determines the effectiveness of the system: 
 
቉. 
(1.12)
Q஺ሺtሻ= 1 െPୗሺtሻቈȽଵଶሺtሻή Ƚଶଷሺtሻ
1 + Ƚଶଵ+ Ƚଶଷ
 
When the probability of system transition from the state of the dangerous situation into the safe condition Ƚଶଵሺtሻ equals the probability of transition from the safe 
condition into the dangerous situation Ƚଵଶሺtሻ, the effectiveness coefficient is defined 
by probability P
ଵ and Ƚଶଷ. If Ƚଶଵሺtሻ is greater than Ƚଵଶሺtሻ, which means the probability of returning is greater than the probability of transitions in a dangerous situation, 
then the protection system is good. 
The most interesting variable, of course, is  Ƚଶଵሺtሻ. It is defined by information 
about sources of danger, protection system, and management system. 
 
 
10 

1.4. The cost of security system 
 
The cost of security system Gୌ୘୉ is the totality of the money resources required to ensure the absence of injuries, death or illnesses in the enterprise, in the 
shop, and in the office, in the school, etc. At the same time, this means of protection 
includes the cost of protection equipment, the cost of training, the cost of signaling, 
the cost of automation, switches, the cost of maintaining the control system, the cost 
of additional premises to accommodate equipment (for example, computers), the 
cost of special clothing. All this is supplemented by operating costs associated with 
equipment maintenance, its periodic inspections and certification, as well as depreciation charges. 
The increase in funds invested in the security system should improve the efficiency. The qualitative dependence of the Q஺ሺtሻ embedded in the security system 
creation Gு்ா looks like this (Fig. 1.3). 
 
 
1.0 
Q஺ሺtሻ 
Gୌ୘୉ 
 
 
Fig. 1.3. Qualitative dependence of efficiency on invested funds 
 
With a minimum investment of funds, first of all, on organizational measures, 
the increase in efficiency is not too noticeable. However, it becomes noticeable when 
the use of technical safety tools starts. Especially the increase in efficiency is noticeable with the use of a comprehensive automated security system. 
 
1.5. Danger and it’s sources.  
Quantitative characteristic of the danger.  
The concept of acceptable risk 
 
Negative impacts in the "human-habitat" system are commonly called danger. 
Danger – a complex of properties of human environmental factors (or a specific 
situation) that can cause adverse health effects under certain exposure conditions.  
The source of danger might be all living and non-living things and all living and 
non-living things can also be endangered. When analyzing dangers, one must proceed 
from the principle “everything affects everything”. Dangers do not possess an elective property and, if they occur, negatively affect on the entire surrounding them material environment. They are realized in the form of flows of energy, substance and 
11