The general objective of the research is to establish a procedure for calculating maintenance costs by systems at the "Carlos Manuel de Céspedes" Thermoelectric company in Cienfuegos, contributing to achieving greater efficiency and effectiveness of the maintenance process and continuous improvement. of the actions of the organization.
The incorporation of the procedure implies a fundamental element in the information system, since it allows controlling and managing the expense elements with accuracy and veracity; in addition to the timely information that it provides for the flow of data in the evaluation of costs in taking corrective actions. The results of this research allow us to determine the costs by systems, particularly those that generate more than 80% of the problems in the object of study, allowing the division of the equipment according to its characteristics and the degree of unavailability, relying on a set of techniques, tools and business management that also facilitated the validation of the procedure.
Introduction
The industrial development of electricity generation, in the territory of Cienfuegos, is becoming more competitive every day. To achieve this objective, work is being done to improve its availability and reliability as the only way to reduce costs and increase its efficiency, as one of the priority tasks of any great modern industry.
However, given the evidence of a real technical-economic recovery in the current moments of the Energy Revolution, there are still notable deficiencies in infrastructure, support for the execution of maintenance, such as: Lack of technical documentation or its obsolescence, lack of a list of equipment and components or insufficient lists, lack of information and technical data. The number of failures cannot be reduced, in many occasions the diagnostic activity is not given the importance it requires ignoring the technical guidelines that the central group derives and there is no adequate way to know the real cost of maintenance and especially the against breakdowns, not only for the inopportune losses that the latter offers the company,but because of the impact they have on the total cost of maintenance.
The present investigation tries to endorse the previous idea through the design of a procedure that allows determining the maintenance costs in the thermoelectric company "Carlos Manuel de Céspedes" in Cienfuegos, made up of Basic Business Units that provide answers to the new associated structure with the Business Improvement.
This leads us to trace the following:
Scientific Problem: How to calculate maintenance costs at the "Carlos Manuel de Céspedes" Thermoelectric company in Cienfuegos?
The following were drawn as solution routes:
Hypothesis: The design and validation of the procedure in the "Carlos Manuel de Céspedes" Thermoelectric Company in Cienfuegos, allows us to know the cost of maintenance by systems.
It is pursued as:
General Objective: To establish a procedure for calculating maintenance costs by systems in the "Carlos Manuel de Céspedes" Thermoelectric company in Cienfuegos.
Specific objectives:
1. Analyze the state of science in the subject under study through a bibliographic compilation.
2. Carry out a technical assessment of the maintenance organization at the Cienfuegos Thermal Power Plant.
3. Present and validate the proposed procedure for determining the maintenance cost for systems at the "Carlos Manuel de Céspedes" Thermoelectric company in Cienfuegos.
Practical benefit
Preparation of a methodological guide for the classification of equipment, managing to determine the systems and equipment in categories according to their productive and economic importance in very important category A, important category B and less important category C, according to their technological complexities, expenses of repair and losses due to unavailable energy, an aspect that is demonstrated in the results of the work.
From the results of the work, the values determined for the highest loss systems according to the analysis of the Pareto application: Feed Water Pumps and Forced Draft Fan, the maximum and minimum expenses for breakdowns and Planned Preventive Maintenance range from 7 to 9% of the total maintenance cost, which differs from traditionally planned, which is between 3 and 5%.
Work Methodology
For the development of the research, different quantitative research methods and techniques were used that, in unity and particular differences, allow the solution of the problem. These methods and techniques favor the fulfillment of the following tasks:
• Review of the specialized theoretical and empirical bibliography for the construction of the state of the art of general reference related to the maintenance activity.
• Verify the proposed procedure.
Development
World and national maintenance trend
The insertion of our industry within the current development in terms of innovative techniques and maintenance systems, rather than a luxury, is a necessity because the country's economy currently depends largely on the search for economic efficiency, which is only It achieves with the quality of the productions, the quantities of productions, for this the efficiency with which the industry can work is closely related to the activity of maintaining the availability of the equipment, in high parameters.
The new techniques that are used in the world related to the maintenance activity that in fact Cuba is at national level in most of its industries applying it, refer to the use of new measurement instruments for the control of state parameters, This allows in a more accepted way to plan only the stops for repairs when necessary, maintenance systems are currently used, adapting them to the productive needs, the cost of spare parts, the safety of the operator, the economy of the company, among other factors. for analysis.
The most recent maintenance systems used are:
• Alternate Maintenance System.
It contains the combinations of maintenance to be used in each particular case in each equipment, which can be:
- Preventive Maintenance by diagnosis (According to State)
- Predictive Maintenance.
- Corrective maintenance.
Instruments used in these new maintenance modalities:
• Vibro meters
• Vibro analyzers
• Infrared lamps for temperatures
• Thickness Gauges
• Novel Computer Programs for statistics and parameter analysis.
Inspective Support Systems:
* Continuous Monitoring Systems: as continuous recorders of status parameters during equipment operation.
* Periodic Monitoring Systems: for inspection purposes with highly qualified workers or technicians for noise control, study of state parameters, use of the 5 senses to detect probable failures in time. In addition to the experience of operators and maintenance personnel.
Types of costs involved in maintenance.
According to Yohn Moubray (2000), maintenance currently ranks second or even first in operating costs. Due to these high costs, and for what an unworked machinery or equipment means economically, new techniques, methods and tools have been developed to try to have zero stops, zero defects within the processes and a detailed study of their costs.
Maintenance involves different costs: direct, indirect and general.
Direct costs:
They are related to the performance of the company and are lower if the conservation of the equipment is better; They influence the amount of time the equipment is spent and the attention it requires. These costs are set by the number of reviews, inspections and in general the activities and controls carried out on the equipment, including:
• Costs of direct and contracted labor
• Costs of materials and direct and contracted spare parts
• Costs of using tools and equipment directly and with contracting.
• Contract costs for carrying out interventions.
Indirect costs:
They are those that cannot be directly attributed to a specific operation or job. In maintenance, it is the cost that cannot be related to a specific job. In general, they are usually: supervision, warehouse, facilities, workshop service, various accessories, administration, public services, etc.
General Costs:
These are the costs incurred by the company to sustain the areas of support or functions that are not properly productive and which in turn support the areas that carry out tasks that are directly related to the business.
For general maintenance expenses to be useful as an analysis tool, they must be classified carefully, in order to separate the fixed cost from the variable, which in some cases are assigned as direct or indirect.
Generally, the costs assigned to maintenance areas due to indirect influences from support areas are not considered since, according to some analysis models, maintenance management has no action, however, when providing the service, there would be no money management infrastructure, security, etc.
It is true that the costs assumed by maintenance areas for administration costs are called assigned costs and are set by levels of authority that go beyond maintenance areas. And also that these costs are generally not considered, because they are not controllable by the maintenance organization, as they are managed by external information systems and their determination is costly.
This point is debatable because although it is true that maintenance is generally not mastered in these aspects, it is also true that maintenance consumes these resources in order to perform its function. One way to visualize this is the abstraction that maintenance is a company, therefore if it did not have that support, it has to be assumed and acquired in order to function.
It is worth acknowledging the difficulty in prorating or calculating the overall maintenance contribution on that resource use. There is the following possibility: determine how much of that global cost corresponds to maintenance and at that point it is best to make a proportional distribution, for example:
- Per person: It is reasonable, therefore, to have as a factor of possession of the resource a value that the administration demands, related to the number of maintenance people with respect to the total. This subsequently allows it to be associated with work as follows: By activity: It is quite appropriate, because it involves a global consumption, the idea is to make a direct relationship of the cost of completing the work order and distribute the general costs with based on a value of total costs.
Validation of the proposed procedure
Next, the proposed procedure is validated to determine the cost of maintenance at the Cienfuegos ETE, validating it through its corresponding stages, a cost that will be separated into planned preventive maintenance (MPP) and maintenance against breakdowns.
Stage I. Classification of plant equipment
It begins by validating the procedure by classifying the teams based on expert criteria to establish classification criteria. Correspondingly, the following tasks are carried out in each of the steps described:
Formation of the work team.
The application of the logical steps of the Delphi Method follows:
1. Initial conception of the problem.
2. Selection of experts.
For the selection of the 13 experts, the following procedure was applied, which consists of the following stages:
1st. Preparation of a list of candidates for experts within the institution who meet the following requirements: Scientific category (Dr., MSc, Ing, Lic.), Years of experience and willingness to participate.
Taking these requirements into account, a group of 22 experts is brought together.
2nd. Determination of the competence coefficient of each expert.
This is a totally anonymous self-assessment method (Ronda Pupo, 2002). The aforementioned survey was applied, in which the candidate expresses the degree of knowledge on the subject of maintenance management in power plants.
It is then concluded that:
As a result of the processing, 13 of the 22 candidates for experts rated themselves as "highly competent" on this topic, 7 candidates were assessed as "medium proficient" and 2 were assessed as "low proficiency".
Classification of plant equipment
The categorization of equipment constitutes one of the elementary steps for carrying out maintenance operations, referring to its organization and technical application. This will determine the type of maintenance that must be performed on each particular equipment.
For the application of this step, all the plant equipment was taken and evaluated according to the 11 evaluation points, ranging from aspects:
- SelectiveDirectivesGeneral
For the processing and analysis of the information contained in the methodology presented above, the SPSS statistical program package in version 12.0 was used.
The following scale was used to categorize the teams in the first round, which was used for all the teams in the first round: very important, normal and conventional.
In order to carry out the first round of the method, the proposed methodology was proposed to the experts, providing the experts with the technical statistical information of the teams, to confirm their agreement regarding the productive importance of the plant equipment, after applied and processed this round the results were the following:
The Kendall's W coefficient, which measures the agreement of the experts, was 0.587 with a significance level of 0.000, the Chi Square statistician was also calculated, which was 320,362 and was compared with the Chi-Square Tabulated with K-1 degrees of freedom equal to 42 and a significance level of 0.05. As can be seen in the results, they show the acceptance of the null hypothesis, they are therefore sufficiently satisfactory, since the Kendall coefficient is high, which indicates that the agreement between the experts is high, the criterion offered by the level of significance it was 0.000 and that is the ideal level of significance that the method should calculate.
As a result of the applied procedure, from the analysis carried out on all the teams, they were finally categorized into category A, B, and C according to their technical-economic importance within the process.
Establish classification criteria
In order to establish classification criteria, it is more convenient to group plant teams by systems, according to the category analyzed to order the necessary data, to facilitate the viability of the procedure, since the systems include several teams that carry out similar maintenance and incur similar breakdowns..
Resulting in six integral systems that group the previously classified teams, listed as follows:
- Forced Draft Fan System Feed Water Pump Systems Circulation Pump Systems Turbine Systems Condensate Pump Systems Gas Recirculator Fan System
To carry out the selection of the integral systems, a study was carried out of all the losses due to plant equipment systems, in the period from 2000 to 2008.
As a result, approximately 83.52% of the failures between the years 2000 and 2008 correspond to the Forced Draft Fan Systems and the Feed Water Pump Systems, with 36.54 and 46.98% respectively, so It can be concluded that in the analyzed period the greatest losses due to unavailable energies are focused on said systems.
In the same way, the planned maintenance by systems was analyzed, observing that the highest% of the necessary losses continues to be focused on the aforementioned systems, despite the fact that the behavior of the other systems cannot be ignored.
From the previous results, the Pareto technique is applied, being defined in the analysis of its characteristics, the systems that are many trivial and few trivial. Despite how it has been shown that the systems that most affect both necessary and unnecessary losses are fan and pump systems.
Application of the "Pareto" Technique
To achieve the selection of the most representative equipment in terms of maintenance and breakdowns, the total of the same defined above is determined, which are organized from highest to lowest number of failures.
Next, a summary table will be prepared with the% of failures and maintenance for the pareto analysis.
Table No. 3.5 Pareto analysis. Source: self made
Finally, the pareto technique is applied to select the teams that are generating the most losses due to unplanned failures. Result shown in the following graph:
Graphic No. 1 Pareto technique. Source: self made
Where:
SBAA: Feed Water Pump Systems
SVTF: Forced
Draft Fans SBCAM: Seawater Circulation
Pumps SBC: Condensate Pumps
S.TURB: Turbines
SVRG: Gas Recirculating Fan
From the previous graph, it could be definitively determined that the teams with the highest losses generated in the plant are those grouped in the following systems:
- Water pumps to feed. Forced draft fans.
Because they are those that are below 80% and that in the other systems it is a loss of the same importance as in the other failures. Here, rather than thinking that the problems of unplanned failures are mainly due to the quality and monitoring of maintenance, it is more convenient to exclusively study the behavior of the selected systems, because by reducing breakdowns and in turn cost we could improve more than 80% in unnecessary losses.
Stage II. Determine the cost for unavailable energy
The objective of this stage is to calculate the cost for losses of Unavailable Energy for rotating equipment, losses that will form part of the total maintenance cost.
After determining the necessary data from historical values from 2000-2008 such as:
- Number of breakdowns and planned maintenance by systems. Hours left to generate. MW quantity. Production values in pesos.
The causes of the breakdowns were first determined for each of the selected systems and later the unavailable energy cost was determined for years. Summarizing the results in the following tables:
Table No. 3.7 Cost for unavailable energy. Breakdowns Source: self made.
Table No. 3.8 Cost for unavailable energy. Maintenance. Source: self made.
From the previous results, it can be concluded that during the analyzed period, $ 6,031,674.74 in unnecessary failures and $ 52,838,190.83 in planned maintenance have ceased, although they are losses that are assumed necessary to be able to win in the future., they must be taken into account when calculating the profit because these losses definitely influence the total cost of maintenance.
Stage III. Determination of total maintenance cost
The objective of this stage is to determine the total cost of maintenance, a result that will be shown on the cost sheet by type of maintenance.
Identification of the elements of the maintenance cost.
In this step, the materials, spare parts, own and contracted direct labor and indirect costs that are used in the maintenance of the chosen systems will be determined by experts. Then they will be classified as direct and indirect.
For this, the team must reflect on the elements that affect the identification of the elements of the maintenance cost.
Determination of the cost of materials and / or spare parts used by types of maintenance.
To obtain the cost of materials and / or spare parts, the gross standard of each type of material and part was multiplied by their corresponding prices, offering the cost of each material for maintenance and grouped by systems.
In summary, in 2008 the total cost of direct material amounted to $ 5,816.4115, 80.76% of which corresponded to breakdowns.
As for the Water Pump System, maintenance is general and variable, it amounted to a cost of $ 22 483.3463 and $ 1 152.9535 related to breakdowns.
Determination of the cost of direct labor by types of maintenance.
Firstly, the hourly wage is obtained, as a result of the division of the basic wage by categories and 190.5 (average wage), then the time standards are obtained for the hourly rates corresponding to the different maintenance operations, resulting in the cost of the basic wage. by type of maintenance. Including the established percentages of complementary salary and social security at the hourly rates of the basic and total salary, respectively.
To show an example of the calculation of the cost of direct labor, we took the year 2008 as a reference. In the case of the feed water pump system, 3 planned maintenance operations were carried out during the year and 9 failures occurred in unit III, equivalent at 96 and 150.91 hours respectively.
The direct maintenance workforce in the Feed Water Pump System is listed resulting in:
• Maintenance mechanic A
• Maintenance mechanic B
• Maintenance mechanic C
• Welder A
To continue the procedure, the hourly wage is determined, as a result of dividing the monthly wage by the average wage of the workers at the plant:
Mechanic A $ 360.00 / 190.50 = $ 1,88976378 x hours
Mechanic B $ 335.00 / 190.50 = 1,75853018 x hours
Mechanic C $ 650.00 / 190.50 = 3.41207349 x hours
Welder A $ 350, 00 / 190.5 = 1,83727034 x hours
Subsequently, the salary expense determined by the multiplication of the hourly wage and the hours worked in maintenance is searched, data reflected in the maintenance technical sheets.
Maintenance Mechanic A is taken as a reference in the case of planned maintenance:
Maintenance mechanic A $ 1,88976378x 96 hours = $ 181.32 salary expense.
Subsequently, 9.09% (Vacations) will be determined based on $ 181.32 and multiplied by the number of mechanics in year (2), resulting in the direct cost of labor for maintenance mechanic A in maintenance planned $ 362.64.
Likewise, the cost of the remaining direct labor will be determined for both planned maintenance and breakdowns in the year itself.
Calculation of the cost of indirect maintenance items.
In this step, the indirect maintenance cost will be determined from the cost inductors in order to make a more accurate allocation of all the indirect elements by type of maintenance, for which the following tasks will be taken into account:
Identification of cost inductors by indirect elements.
The selection of the most suitable inductors is a function of the parameter that most influences the variation in costs.
In each indirect element it is possible to establish or detect the existence of several different cost drivers, so the problem that appears is to choose the most appropriate to undertake the allocation process.
The inductors selected by indirect elements are shown below:
Table No.3.12 Inductors of costs for indirect elements. Source: self made.
Assignment of indirect elements to types of maintenance.
The objective of this task is to determine an allocation rate for the indirect elements to the types of maintenance, through the inductor previously selected, which makes it possible to assign them more accurately.
In the case of depreciation, a rate was determined from the balance of the equipment that makes up the systems under study, calculated by the ratio between the depreciation and the selected inductor.
For the remaining indirect expenses, a% distribution was determined in each inductor selected by type of maintenance, represented by the division of the inductor of each maintenance and the total of the inductors previously defined in table 3.12 Representing the measure of resource consumption that each inductor has needed to carry out its mission, or in other words, the% that the inductor represents within each type of maintenance.
Preparation of cost sheet by types of maintenance
In this step, the total maintenance cost in the periods analyzed was determined, through the preparation of a cost sheet by type of maintenance, which will contain all the costs of materials and spare parts, wages, and other indirect costs, which they are required for the maintenance in each system, serving for the preparation of the work order and the selection of a minimum and maximum range of costs by types of maintenance, for future planning of the maintenance cost.
To determine the range that maintenance cost has fluctuated, the cost summary for the study years was shown.
It is concluded that the maintenance cost in the Food Water Pump System has fluctuated within the analyzed period 2000-2008, between $ 1,012.33 and $ 410,254.71, a cost that includes the elements of the maintenance cost.
When analyzing the behavior of the cost by types of maintenance, it is appreciated that the planned maintenance has a greater range, since it represents 92.71% of the total maintenance cost of the pump system. The summary is shown in the following table:
|
Feed Water Pump System |
||
| Maximum cost | Minimal cost | |
| Breakdowns |
$ 25 741.27 |
$ 1012.33 |
| Planned Maintenance |
$ 410 254.71 |
$ 30 237.40 |
Table No. 3.15 Cost range of the feed water pump system.
Source: self made.
Likewise, the cost behavior of the forced draft fan system was analyzed, the results are shown below:
The maintenance cost on the forced draft fan system has ranged from a cost range of $ 1,811.34 to $ 383,948.25. In summary, the highest-ranking maintenance is general, as it represents 70% of the total maintenance cost in the fan system. The selected ranges are shown below:
|
Forced Draft Fan System |
||
| Maximum cost | Minimal cost | |
| Breakdowns |
$ 57 911.86 |
$ 1,811.34 |
| Light |
$ 46 022.06 |
$ 8 897.24 |
| general |
$ 383 948.25 |
$ 6 831.79 |
Table No. 3.16 Cost range of the forced draft fan system. Source: self made.
Analysis of the results
The proposed procedure allows the following results from a process, quantitative and qualitative:
- Determine the systems and equipment in categories according to their productive and economic importance in very important category A, important category B and less important category C, according to their technological complexities, repair costs and losses due to unavailable energy, an aspect that is demonstrated in the results of the work.
The application of analysis in groups of experts, as well as the collection of data from archives of the area of planning, operation, maintenance inspection and economic results in the following:
- Know the flow and how to acquire the necessary data for the analysis of maintenance and expenses, both direct and indirect, that are incurred. Carry out a more realistic assessment of the cost of maintenance in a more detailed way by particular systems, which is done in a general way in the current applied system. The proposed procedure allows to assess and compare the expenses in a more real way according to what was planned, since it allows to assess the possible deviations, between the expenses in the workshops not quantified by the warehouses for the use of surplus resources and those not controlled in the orders issued by not putting the materials actually extracted.The information of the expenses in each one of the issued work orders is not submitted to final analysis, remaining in the files of each one of the teams. In economics, only the costs of materials removed from the warehouse for a generally determined maintenance are valued as an essential aspect, but the specific expense for each system is not identified. In the planning area, only what is planned is valued in detail, but the final result is not taken into account for the comparative analysis of what is planned against what is actually spent.In the planning area, only what is planned is evaluated in detail, but the final result is not taken into account for the comparative analysis of what is planned against what is actually spent.In the planning area, only what is planned is valued in detail, but the final result is not taken into account for the comparative analysis of what is planned against what is actually spent.
From the results of the work, the values determined for the systems with the highest loss according to the analysis of the Pareto application: BAA and VTF, the maximum and minimum expenses for breakdowns and MPP range between 7 and 9%, which differs from what was traditionally planned. which is between 3 and 5%.
Conclusions
The maintenance control activity in the company requires scientific-technical rigor, since otherwise it is a good intention that can discredit it and cause problems in the subsequent development of its productive activity.
1. The results provided by the current information system do not allow the determination of maintenance costs for systems in plants, as they do not assess specific characteristics of the equipment in the maintenance activity.
2. The proposed procedure allows:
• Control the systems that generate the most losses and take preventive measures to reduce them.
• Compare more accurately the expenses for the two access routes, both economic and maintenance planning, giving you a better use and application of the existing data in files of the maintenance planning area.
3. The actual costs of system maintenance have fluctuated as follows:
• Forced Draft Fan Systems: $ 1,811.34 and $ 383,948.25.
• Food Water Pump System: $ 1,012.33 and $ 41,0254.71.
recommendations
1. Create a group of experts, familiar with all areas of the ETE and maintenance activities, who work together with a computer scientist to manage to automate the procedure, adapt it and exploit it.
2. Provide knowledge, information, and experiences gained to other thermoelectric companies in order to obtain good feedback.
3. Improve the planning of expenses for both materials and labor.
4. Apply the proposed procedure in order to achieve a better distribution and control of maintenance costs.
Bibliography
Anay Rivero Ávila,, Moreira,, RJV & Bernal, SC, 1990. Maintenance by Diagnosis and Balance of Rotating Equipment in Thermoelectric Power Plants, p.96 h.
Ángel Sáez Torrecilla, A. Fernández Fernández and G. Gutiérrez Díaz, 1993. Cost Accounting and Management Accounting. In Spain: McGrawHill, p. 438p.
Banco, F., 1993. Cost and management accounting., Bilbao:: Ediciones Deusto SA,
Bravo., OG, 1997. Cost accounting, Colombia: Mc Graw - Hill, Lerner Ltda.
Bruel, Kjaer. -: /ss/,1984.-34 p., 2008. Bruel Predictive Maintenance. Available at:.
CDA, 1987. General Guidelines for Planning and Cost Determination. Planned economy. In Havana, p. 178-226.
Castillo Morales, Gabriel, 1999. Maintenance of Equipment, Machines and Installations, Cienfuegos.
Collective of Authors. 1992. Colloquium on maintenance training. Maintenance (Spain), p.25-32.
Corrales, Antonio.: 25-27., 1993. Reflection on maintenance in modern industries. Maintenance (Spain).
De Gusmao, CA, 2001. Indices de Desempenho da Manutencao: A Practical Approach. Maintenance Club., (No 4. Year 1. Brazil.).
FGS, 1994. Comprehensive Diagnosis.
FGSD, 1994. Comprehensive Diagnostic Methodology for Power Plants and Sub-Stations.
Fernández, Antonio., Cost Accounting and Management Accounting: A delimiting proposal. Available at:.
HT Jonson, RS Kaplan., 1988. Cost accounting, Barcelona.
Hargadón, BJ, 1995. Cost Accounting 2nd ed., Mexico: Mac-Graw-Hill Interamericana.
Hernández Cruz, E and Navarrete Pérez, E., 2001. System for calculating indicators for maintenance. Maintenance club.Brazil., (No 6).
Tavares, LA, 2000. Maintenance Outsourcing., (December No. 3), p.2.
