Article

Development of Lift Control System Algorithm andP-M-E Analysis in the Workplace

Inikuro Afa Michael

Department of Computer Engineering, Taras Shevchenko National University of Kyiv, 01033 Kyiv, Ukraine;afamichaelinikuro@yahoo.co.uk; Tel.: +380-63-226-1958

Received: 4 September 2018; Accepted: 10 October 2018; Published: 12 October 2018

Abstract: Lifts play an important role in human transportation in multi-storage buildings, whichexperience continuous improvements to their architecture and structure. As a result of theseimprovements, the development of efficient lift systems with more programs is required to meetthese changes. In this work, a lift control system based on a programmable logic controller(PLC) is introduced, elucidating the development of the lift control algorithm and network basedon a dispatching algorithm that utilizes a fuzzy system and exploits the traffic situation andcondition. The PLC language ladder logic is implemented to facilitate a reduction in the averagewaiting time of passengers and the power consumption. Ladder diagrams for different scenariosare compared. The analysis of personnel-machine-environment (P-M-E) system conditions wasconducted, examining numerous physical factors that could pose health and safety threats to workers.The present study opens doors for future lift systems studies based on PLC and the estimation of asafe workplace for machines and operators.

Keywords: PLC; ladder logic; lift control system; P-M-E system; fuzzy systems

1. Introduction

Lifts are essential motor-powered vertical media of transportation in residential, commercial andindustrial buildings that play a huge role in the movement of people around these environments.Nowadays, as a result of tremendous development in the structural and architectural engineeringin multi-storage buildings, lifts have become inevitable and a key requirement for humantransportation [1]. Lifts are used in almost all the multi-storage buildings of metropolitan areasand hence, it is important to replace the traditional relay logic controlled lifts with more programmabletechnology based lifts for better efficiency, such as PLC [2,3].

These relay controlled systems have several limitations, such as a high fault ratio, difficulty inreplacing flawed parts of the automated system and highly complex circuitry. Another drawbackis the difficulty in providing fault tolerance using relay logic. PLC serves as a more enhancedreplacement for designing modern lift control systems to circumvent these shortcomings and improvethe troubleshooting of the system by allowing for easy monitoring of the inputs and outputs viahuman-machine interaction (HMI) devices, such as the HMI–LED indicator, better operational speed,reliability and relatively lower costs compared to other programmable control systems [4–8]. PLC hasbeen successfully demonstrated in several control studies, including lift control systems [9–14].

When designing lifts with PLC, the dispatching algorithm is one of the most important aspectsin the control system and therefore, an efficient algorithm can reduce the average waiting time ofpassengers to a remarkable average of 25 s or less and also reduce the power consumption of thelift system. Six main types of dispatching algorithms are generally implemented, which are namely:(i) Collective up—CU; (ii) Collective down—CD; (iii) Selective up—SU; (iv) Selective down—SD;

Appl. Syst. Innov. 2018, 1, 38; doi:10.3390/asi1040038 www.mdpi.com/journal/asi

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(v) Selective-collective up—SCU; and (vi) Collective-selective down—CSD algorithms [5]. The choiceof the preferred algorithm is selected on a specific instance based on the traffic amount and percentage.

To achieve an efficient control system, the algorithm employs a fuzzy scheme to improve controlbased on logical reasoning and implementing systems through programmed expert knowledge.The concept of a fuzzy control system was first introduced by L.A. Zadeh as he introduced theconcept of linguistic variables that serve as fuzzy sets (i.e., input variables in the fuzzy control) [15,16].The fuzzy system is normally divided into four main parts, which are namely fuzzy knowledgerules, fuzzifier, fuzzy inference engine and the defuzzifier. This is done to transfer the input signalinto linguistic terms and the inference makes the calculations and decision to prioritize certain liftassignment. Furthermore, the output information is converted by the defuzzifier into a single signalthat serves as the control instructions [17]. The concept of fuzzy control and fuzzy logic has beenextended to lift control and group control systems. The early to mid 1990s led to a boom in theimplementation of fuzzy logic in lift systems [18–22]. Kim et al. [23,24] demonstrated a design basedon a fuzzy control model that identifies traffic patterns and implements the traffic patterns and trafficmode based on information, such as traffic percentage, time, area-weight and other linguistic terms.Dewen et al. further demonstrated a fuzzy logic in group supervisory control, which demonstrates anoptimum lift vehicle assignment with control devices [25].

Recent studies have introduced novel approaches for applying fuzzy logic in order to improvethe expert prediction of lift control as compared to the old methods to increase efficiency in lift systemsand energy optimization [26–28]. Jamaludin et al. further extended conventional fuzzy lift systems byintroducing a self-tuning mechanism to adapt the control system to the continually changing trafficwith better precision [29,30]. Some recent studies have demonstrated a lift system that employs fuzzycontrol systems and PLC. PLC is shown to be fast and adaptable to multiple inputs and outputs tomeet traffic demands, which makes it suitable for this present study [31,32]. Other benefits of usingPLC in this type of design is that it can be incorporated in more complex applications and can be easilyadapted to other systems, such as the control of automated machinery systems, including cranes androbotic arm manipulator [33,34].

P-M-E refers to the optimal relationship between personnel (people in the work place andresponsible for the operation of machine), machine (the computer and other control systems) andthe environment (the prescribed work conditions for personnel–machine interaction). Even thoughfuzzy logic systems are very intelligent, they still lack the full mastery of the entire system, especiallyrelating to installation, troubleshooting and maintenance. As a result, lifts can be considered to bea purely personnel-machine-environment system. Therefore, they require operators to oversee theoptimal functioning. Sometimes, depending on the number of operators required, the conditions ofthe workplace change. Hence, the need for this analysis is to achieve a safe, highly efficient and costeffective system and work environment for the operators [35,36]. Lifts are considered to be vital assetsin corporate buildings and as a result, its maintenance is paramount.

In this paper, the development of the lift control network is briefly introduced in Section 2, withthe development of the control algorithm explained; the fuzzy control system described based onits input variables, fuzzification, fuzzy inference and defuzzification processes; and the PLC tasksillustrated. The ladder logic diagram is introduced and compared for different scenarios in Section 2.2.Finally, the analysis of the P-M-E system in the workplace is discussed in Section 3. The present studypresents a simplified lift control system using a PLC algorithm based on fuzzy logic scheme that canbe easily implemented and adapted to other control system designs.

2. Control Network Development

The lift system controller design operates with division zoning technique and a fuzzy controlsystem for the efficient computing of fitting values Fp for a quicker lift hall-call. These fitting valuescomputation is based on numerous lift performance conditions, such as the waiting time of thepassengers, load capacity and distance between floor hall-calls. The controller implements a fuzzy

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system in traffic pattern recognition, while the division zoning scheme helps in tailoring the controlleraccording to the patterns from the fuzzy system [23,24,37].

The fuzzy system used in this work is divided into three main parts: (i) fuzzification; (ii) fuzzyinference; and (iii) defuzzification. The fuzzifier helps to classify the traffic patterns by converting thesignal into a set of fuzzy variables. The signal is translated into five linguistic terms, which are namelyvery large (VL), large (L), medium (M), small (S) and very small (VS). The traffic patterns are receivedin terms of the number of passengers going in different directions, which is namely upwards (UP) ordownwards (DN), and also in the case of steady state traffic. The priority is given to the direction withhigher traffic, i.e., if UP = VL and DN < VL (L, M, S, VS), Fp = High Priority is thus assigned to UP.

Once the traffic direction is identified, the input information is passed to the fuzzy inferenceengine along with extra linguistic variables, such as (a) waiting time (WT); (b) space availability in lifts(SA); and (iii) distance between the elevators and distance of hall-calls floors and destination floors(Dist). The inference engine serves as the fuzzy decision block, which calculates the entire Fp to setthe priority for the number of lifts (N) based on a rule sets (Fp = High, Medium or Low) as shown inTable 1.

Table 1. Fuzzy knowledge rules for waiting time (WT), space availability (SA) and distance (Dist).

IF THEN (Fp)

WT = Short HighWT = Medium Medium

WT = Long Low

SA = Large HighSA = Medium Medium

SA = Small Low

Dist = Less HighDist = Medium Medium

Dist = High Low

This means that for a smaller loading, closer proximity of lifts, shorter waiting times and highernumber of passengers waiting, the priority is assigned to a lift with highest combined Fp. These detailsare sent to the defuzzifier, which generates a single output based on the total priority assigned. This isconducted on the number of lifts (N) and the traffic mode is subsequently set.

The defuzzification process employs the center of gravity method, which assigns the priorityaccording to the total fitting values for 1 to N lifts. The lift with the highest total priority fittingvalue is assigned as the main preference and the information is passed as a single real traffic output.This output value serves as control instructions for responding to lifts according to the traffic data andhall-call assignment.

In this section, we will look at the development of the lift control algorithm and the programminglanguages used.

2.1. Development of Lift Control Algorithm

As stated previously, the algorithm employed is used to control the lift system through thedivision zoning and a fuzzy system. This takes into account the fact that the division zones representlifts in the building, which are dependent on the hall-call requests. The present algorithm is comprisedof three phases: (i) the identification in phase 1; (ii) the response in phase 2; and (iii) the execution inphase 3.

In phase 1, the algorithm assigns zones with the aid of a fuzzy traffic controller, which wassimilarly described in the work of Patiño-Forero et al. [31], that identifies if a lift is free or not byanalyzing information, such as the occupation and capacity of the lift on the floor from which the

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hall-call was made. Furthermore, it also utilizes the information related to whether this call wasintended to go upwards or downwards.

Phase 2 is only initiated in a case of a free lift. In this case, the fuzzy system fitting valuecalculations for quick hall responses are initiated by the algorithm. Once the lift is considered to beoccupied, phase 3 commences, in which the algorithm executes the inputted information from thehall-call until the lift is free again. The lift control algorithm employs an open platform communication(OPC) between the fuzzy control system and the PLC, which is suitable for the reception of data fromdevices, such as HMI devices. The flowchart for the algorithm design is shown in Figure 1.

The main task of the design is related to the logic that is essential for controlling the movement ofthe lift between the floors of the building. The main conditions are stated as follows. (1) There must beupward and/or downward button(s) to make a hall-call. If there is no call, the lift retains its currentposition. In the cases of multiple calls from different floors, the response is made based on the timeorder of when the call was made. (2) The door of the lifts will have a programmed door that opensand closes automatically on every floor of the building.

PLC programming languages that are generally used in lift control system design includethe follows: (i) Structure text (ST); (ii) Instruction list (IL); (iii) Function block diagram (FBD);(iv) Sequence function chart (SFC); and (v) Ladder (logic) diagrams (LL/LD). Ladder logic is agraphical programming language that is extracted from the circuitry evolution of the relay controlwiring [13]. In this present work, the ladder logic, which is the most commonly used language toprogram the PLC, was employed.

Appl. Syst. Innov.2018, 2, x FOR PEER REVIEW 4 of 10

Phase 2 is only initiated in a case of a free lift. In this case, the fuzzy system fitting value

calculations for quick hall responses are initiated by the algorithm. Once the lift is considered to be

occupied, phase 3 commences, in which the algorithm executes the inputted information from the

hall-call until the lift is free again. The lift control algorithm employs an open platform

communication (OPC) between the fuzzy control system and the PLC, which is suitable for the

reception of data from devices, such as HMI devices. The flowchart for the algorithm design is

shown in Figure 1.

The main task of the design is related to the logic that is essential for controlling the movement

of the lift between the floors of the building. The main conditions are stated as follows.(1) There

must be upward and/or downward button(s) to make a hall-call. If there is no call, the lift retains its

current position. In the cases of multiple calls from different floors, the response is made based on

the time order of when the call was made. (2) The door of the lifts will have a programmed door that

opens and closes automatically on every floor of the building.

PLC programming languages that are generally used in lift control system design include the

follows: (i) Structure text (ST);(ii) Instruction list (IL); (iii) Function block diagram (FBD); (iv)

Sequence function chart (SFC); and (v) Ladder (logic) diagrams (LL/LD). Ladder logic is a graphical

programming language that is extracted from the circuitry evolution of the relay control wiring [13].

In this present work, the ladder logic, which is the most commonly used language to program the

PLC, was employed.

Figure 1.Flowchart representing the algorithm execution in different phases.

2.2.Ladder Logic

The ladder logic network is established based on the pre-selected PLC prerequisites, such as the

input signal from the hall-call. Some of the ladders that are responsible for tracking the status of

different pushes are described in Figures 2 and 3.

Ladder diagrams are interpreted from left to right and from top to bottom. The rungs, which are

also referred to as networks, have several control elements with a single output coil. Table 2

describes the logic input information from the ground floor as illustrated in network 1 of Figure 2a.

Table 2.Logic input information from the ground floor as seen in Figure 2.

Symbol Address Comment

indcatr_Gnd Q0.0 indicator of ground floor request

Figure 1. Flowchart representing the algorithm execution in different phases.

2.2. Ladder Logic

The ladder logic network is established based on the pre-selected PLC prerequisites, such asthe input signal from the hall-call. Some of the ladders that are responsible for tracking the status ofdifferent pushes are described in Figures 2 and 3.

Ladder diagrams are interpreted from left to right and from top to bottom. The rungs, which arealso referred to as networks, have several control elements with a single output coil. Table 2 describesthe logic input information from the ground floor as illustrated in network 1 of Figure 2a.

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Table 2. Logic input information from the ground floor as seen in Figure 2.

Symbol Address Comment

indcatr_Gnd Q0.0 indicator of ground floor requestMax Entries_Qu VWO maximum no. of entries in the queue/starting address of tableReq_Gnd_Floor 10.0 request coming from ground floor

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Max Entries_Qu VWO maximum no. of entries in the queue/starting address of table

Req_Gnd_Floor 10.0 request coming from ground floor

Figure 2.Ladder diagrams for: (a) Reception and storage of information from touch sensor on the

ground and first floor represented as networks 1 and 2; and (b) Storage of information related to the

current position of the lift.

It is important to take a look at the ladders tracking the touch sensors. We can see that from

Figure 2, the normal open contact here is responsible for receiving and storing the information

received from the touch sensor. After this, the second symbol stores the position of the lift. The

information is sent to the counter for processing and the position of the lift is stored in the counter

ready for execution.

Figure 3.Ladder diagrams for: (a) Combining, storing and checking all required conditions; (b)

Driving the conditions in the output; and (c) Automated movement of the doors of the lift.

The ladder diagram in Figure 3a is responsible for combining and storing all the conditions

received (i.e., ladders for checking all required conditions). Based on the results of this condition, the

Figure 2. Ladder diagrams for: (a) Reception and storage of information from touch sensor on theground and first floor represented as networks 1 and 2; and (b) Storage of information related to thecurrent position of the lift.

It is important to take a look at the ladders tracking the touch sensors. We can see that fromFigure 2, the normal open contact here is responsible for receiving and storing the information receivedfrom the touch sensor. After this, the second symbol stores the position of the lift. The information issent to the counter for processing and the position of the lift is stored in the counter ready for execution.

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Max Entries_Qu VWO maximum no. of entries in the queue/starting address of table

Req_Gnd_Floor 10.0 request coming from ground floor

Figure 2.Ladder diagrams for: (a) Reception and storage of information from touch sensor on the

ground and first floor represented as networks 1 and 2; and (b) Storage of information related to the

current position of the lift.

It is important to take a look at the ladders tracking the touch sensors. We can see that from

Figure 2, the normal open contact here is responsible for receiving and storing the information

received from the touch sensor. After this, the second symbol stores the position of the lift. The

information is sent to the counter for processing and the position of the lift is stored in the counter

ready for execution.

Figure 3.Ladder diagrams for: (a) Combining, storing and checking all required conditions; (b)

Driving the conditions in the output; and (c) Automated movement of the doors of the lift.

The ladder diagram in Figure 3a is responsible for combining and storing all the conditions

received (i.e., ladders for checking all required conditions). Based on the results of this condition, the

Figure 3. Ladder diagrams for: (a) Combining, storing and checking all required conditions; (b) Drivingthe conditions in the output; and (c) Automated movement of the doors of the lift.

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The ladder diagram in Figure 3a is responsible for combining and storing all the conditionsreceived (i.e., ladders for checking all required conditions). Based on the results of this condition,the output (i.e., motor drive) is driven by the ladder seen in Figure 3b. The motor executes its actionfrom the output received from the other ladders. The examples of the conditions include: next floorwaiting for service, the current lift position and next destination, etc.

The door of the lift is also automated based on the movement of the lift, which means that whenthe lift is in motion, the door of the lift will be closed and will remain open for the rest of the time.The ladder to achieve this goal is shown in Figure 3c.

3. P-M-E System Analysis in the Workplace

Labor protection is important for creating a workplace with safe and healthy labor terms.The major labor protection terms are examined in order to reduce the influence of any dangerous workenvironment factors on workers [38,39]. Therefore, P-M-E system analysis is done as described inFigure 4, showing the relationship of personnel (P), machine (M) and environment (E).

The important part of this project was conducted in the workplace of a small lab with dimensionsof 8 m × 6 m × 4 m. Accordingly, the area of the room is equal to 48 m2. The area of the windows was3 m × 2 m = 6 m2. The workplace has double-sided windows and a door, which allows for an amountof air entrance for ventilation. The width of the evacuation exit is equal to 2 m × 0.8 m = 1.6 m2. In theworkplace, there are five people (p = 5) working on different projects and they all use computersto operate particular functions for these projects. An equipment in the workplace feeds from thethree-phase, four-wire electric system with the dead earthed neutral, as shown in Figure 5. This has atension of 380/220 V and a working tension of 220 V. Furthermore, the working frequency was 50 Hz.

With regards to the normal terms of labor, the volume of workplace should not be less than 20 m3

and area of 6 m2 forone operator of the PC. In this present study, we ran the following calculations: thearea (A) of working place = 8 m × 6 m = 48 m2 and the volume (V) = 8 m × 6 m × 4 m = 192 m3. Atpresent, the area/no. of people = 192/5 = 10.6 m2 and volume/People = 192/5 = 41 m3. Hence, thevolume and area on one operator of the working place are in accordance to the terms of labor [40,41].

Appl. Syst. Innov.2018, 2, x FOR PEER REVIEW 6 of 10

output (i.e., motor drive) is driven by the ladder seen in Figure 3b. The motor executes its action

from the output received from the other ladders. The examples of the conditions include: next floor

waiting for service, the current lift position and next destination, etc.

The door of the lift is also automated based on the movement of the lift, which means that when

the lift is in motion, the door of the lift will be closed and will remain open for the rest of the time.

The ladder to achieve this goal is shown in Figure 3c.

3. P-M-E System Analysis in the Workplace

Labor protection is important for creating a workplace with safe and healthy labor terms. The

major labor protection terms are examined in order to reduce the influence of any dangerous work

environment factors on workers[38,39]. Therefore, P-M-E system analysis is done as described in

Figure 4, showing the relationship of personnel (P), machine (M) and environment (E).

The important part of this project was conducted in the workplace of a small lab with

dimensions of 8m×6m×4m. Accordingly, the area of the room is equal to 48m2. The area of the

windows was 3m×2m = 6m2. The workplace has double-sided windows and a door, which allows for

an amount of air entrance for ventilation. The width of the evacuation exit is equal to

2m×0.8m=1.6m2. In the workplace, there are five people (p=5) working on different projects and they

all use computers to operate particular functions for these projects. An equipment in the workplace

feeds from the three-phase, four-wire electric system with the dead earthed neutral, as shown in

Figure 5. This has a tension of 380/220V and a working tension of 220V. Furthermore, the working

frequency was 50 Hz.

With regards to the normal terms of labor, the volume of workplace should not be less than

20 m3 and area of 6m2forone operator of the PC. In this present study, we ran the following

calculations: the area (A) of working place = 8m×6m =48m2 and the volume (V) =8m×6m×4m =192m3.

At present, the area/no. of people = 192/5= 10.6m2and volume/People = 192/5= 41m3. Hence, the

volume and area on one operator of the working place are in accordance to the terms of labor[40,41].

Figure 4.The general structure of the P-M-E system with descriptions in Table 3.

Table 3. List of connections in the general system of P-M-E shown in Figure 4.

Number of

Connection Directions Comment

1 P1-M1 Influence of personnel on management

Figure 4. The general structure of the P-M-E system with descriptions in Table 3.

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Table 3. List of connections in the general system of P-M-E shown in Figure 4.

Number ofConnection Directions Comment

1 P1-M1 Influence of personnel on management2 M1-P1 State information machine processed by personnel3 M1-TW Influence of machine on the goal of work4 TW-P3 Influence of the goal of work on the psycho-physiological state of personnel5 P3-P1 Influence of the state of organism of personnel on quality of his work6 M2-P3 Personnel under the influence of dangerous production factors7 M3 . . . M7-E Influence of machine on an environment8 E-P3 . . . P7 Influence of environment on the state of organism of personnel9 E-M1 Influence of environment on the machine

10 P1-M2 Influence of personnel on the emergency state of machine11 P2-E Influence of personnel as a biological object on an environment

12 P3-P2 Influence of the psycho-physiological state on the intensity of exchange ofmatters between an organism, environment and physiology of personnel

13M1-M2 Necessary information for making emergency influenceM2-M1 Managing emergency influences

AThe system of

external controlA- P1

Managing information about technological process from the externalcontrol of the system

Task 1. Calculation of current passing through the body of man at a unipolar and bipolar touch.

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2 M1-P1 State information machine processed by personnel

3 M1-TW Influence of machine on the goal of work

4 TW-P3 Influence of the goal of work on the psycho-physiological state of personnel

5 P3-P1 Influence of the state of organism of personnel on quality of his work

6 M2-P3 Personnel under the influence of dangerous production factors

7 M3…M7-E Influence of machine on an environment

8 E-P3…P7 Influence of environment on the state of organism of personnel

9 E-M1 Influence of environment on the machine

10 P1-M2 Influence of personnel on the emergency state of machine

11 P2-E Influence of personnel as a biological object on an environment

12 P3-P2 Influence of the psycho-physiological state on the intensity of exchange of

matters between an organism, environment and physiology of personnel

13 M1-M2 Necessary information for making emergency influence

M2-M1 Managing emergency influences

A

The system

of external

control A- P1

Managing information about technological process from the external

control of the system

Task 1.Calculation of current passing through the body of man at a unipolar and bipolar touch

Figure 5.The body of a man at a unipolar and bipolar touch.

In this variant, a man touches two phase wires (biphasic touch). In this case, a current flowing

through the human body can be calculated using this formula:

Ipeople =Vlinear

Rpeople

whereVlinear is the linear voltage =380 V;Rpeople is the resistance of people = 1.4; and Ipeople: current of

people = unknown. To calculate the value of current, we use the following formula:

Ipeople =380

1.4 × 103= 0.27 A

This current (271mA) with 50-Hz frequency causes cardiac arrest without fibrillation. If the

effect of the current last 1 to 2 s and causes no damage to the heart, a person usually resumes normal

activity on their own after the power failure.

Task 2.Calculation of crossing of send-offs and cables for the economy of density current

The formula for its calculation is given as:

Sec =Imax

Jec

where Imax is the current line during the normal work of network with a SI unit of A; and Jec is the

economical current density with a SI unit of A/mm2, which is determined depending on the material

and time of usage of the maximal loading. In the case of bare copper conductors with current, Sec =9

3.0= 3 mm2 . Anything less than 3mm2 can cause electrocution due to the high current flowing

through the copper wire, which increases the heat and causes the wire to change to heated red color.

Figure 5. The body of a man at a unipolar and bipolar touch.

In this variant, a man touches two phase wires (biphasic touch). In this case, a current flowingthrough the human body can be calculated using this formula:

Ipeople =VlinearRpeople

where Vlinear is the linear voltage = 380 V; Rpeople is the resistance of people = 1.4; and Ipeople: currentof people = unknown. To calculate the value of current, we use the following formula:

Ipeople =380

1.4 × 103 = 0.27 A

This current (271 mA) with 50-Hz frequency causes cardiac arrest without fibrillation. If the effectof the current last 1 to 2 s and causes no damage to the heart, a person usually resumes normal activityon their own after the power failure.

Task 2. Calculation of crossing of send-offs and cables for the economy of density current.

The formula for its calculation is given as:

Sec =Imax

Jec

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where Imax is the current line during the normal work of network with a SI unit of A; and Jec isthe economical current density with a SI unit of A/mm2, which is determined depending on thematerial and time of usage of the maximal loading. In the case of bare copper conductors with current,Sec =

93.0 = 3 mm2. Anything less than 3 mm2 can cause electrocution due to the high current flowing

through the copper wire, which increases the heat and causes the wire to change to heated red color.

Task 3. Estimation of shut-down ability of devices maximal current defense.

The short circuit current, Ish is calculated as Ish =Vph

Zph−0, where Vph is the phase tension with a SI

unit of V; and Zph-0 is an impedance of loop a «phase-zero» with a SI unit of Ω.The device of maximal current defense is provided by the reliable disconnection of users of electric

power from the network if a condition is executed, which is calculated as:

Inom ≤ Ish

E

where Inom is the nominal current of the fusible insertion of safety device. The current electromagneticinsertion of circuit breaker on short-circuit has a SI unit of A. Furthermore, E is a coefficient of multiplesof current (according to NPAOP 40.1-1.21-98 [42] for fuse E = 3 or for the electromagnetic breaker,E = 1.4 or 1.25).

For a fuse:

Vph = 220 v; Zph − 0 = 20 Ω; Ish =Vph

Zph−0=

22020

= 11VΩ

Inom ≤ Ish

E=

113

= 3.66

Inom ≤ 3.66

Another important task is the calculation of the necessary amount and types of fire-extinguishers.For safety purposes, the computer room should be provided with these types of denotation of fireextinguisher: (i) BBk-1,4, BBk-2 Carbon-dioxide and (ii) BBk-3,5, BBk-5 Carbon-dioxide. Fire safety isan important condition of security of the personnel, property, society and state from fires. In additionto the provision of fire extinguishers, alarm systems are installed for the detection of fire by initiatingaudiovisual signals as hazard warnings.

4. Conclusions

In this paper, the development of the lift control system algorithm is discussed. It is shown thatthe network development is based on the traffic patterns and the zoning division using the fuzzy liftcontrol system. The ladder logics for understanding the evolution of the electrical circuitry of the PLCcontrolled lift system are discussed and compared.

The personnel-machine-environment system analysis is conducted to ensure not only the safety ofworkers but also the smooth operation of the machine and the workplace. The present study providesan insight for future studies that should focus on the implementation of lift control systems andcreating an excellent working environment for their efficient operation.

Funding: This research received no external funding.

Acknowledgments: The author acknowledges the support of the research technicians of the Faculty of ComputerEngineering of the Kharkov National University of Radio-electronics and the regular research visits hosted.

Conflicts of Interest: The author declares no conflict of interest.

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