How to draw up an annual maintenance schedule for electrical equipment? I will try to answer this question in detail in today’s post.
It's no secret that the main document by which electrical equipment is repaired is the annual schedule of preventive maintenance of electrical equipment, on the basis of which the need for repair personnel, materials, spare parts, and components is determined. It includes each unit subject to major and routine repairs of electrical equipment.
To draw up an annual preventive maintenance schedule (preventive maintenance schedule) for electrical equipment, we will need standards for the frequency of equipment repairs. This data can be found in the manufacturer’s passport data for electrical equipment, if the plant specifically regulates this, or use the reference book “System for Maintenance and Repair of Power Equipment.” I use the A.I. reference book. FMD 2008, therefore, further I will refer to this source.
Download the reference book A.I. Foot and mouth disease
So. Your household has a certain amount of energy equipment. All this equipment must be included in the maintenance schedule. But first, some general information about what the annual PPR schedule is.
Column 1 indicates the name of the equipment, as a rule, brief and clear information about the equipment, for example, name and type, power, manufacturer, etc. Column 2 – number according to the scheme (inventory number). I often use numbers from electrical single-line diagrams or process diagrams. Columns 3-5 indicate service life standards between major repairs and current ones. Columns 6-10 indicate the dates of the last major and current repairs. In columns 11-22, each of which corresponds to one month, the symbol indicates the type of planned repair: K - capital, T - current. In columns 23 and 24, respectively, the annual equipment downtime for repairs and the annual working time fund are recorded. Now that we have examined the general provisions about the PPR schedule, let’s look at a specific example. Let's assume that in our electrical facilities, in building 541, we have: 1) a three-phase two-winding oil transformer (T-1 according to the diagram) 6/0.4 kV, 1000 kVA; 2) pump electric motor, asynchronous (designation according to scheme N-1), Рн=125 kW; Step 1. We enter our equipment into the empty PPR schedule form.
Step 2. At this stage, we determine the resource standards between repairs and downtime. a) For our transformer: open the reference book p. 205 and in the table “Standards for the frequency, duration and labor intensity of repairs of transformers and complete substations” we find a description of the equipment that is suitable for our transformer . For our power of 1000 kVA, we select the values of the frequency of repairs and downtime during major and current repairs, and write them down in our schedule.
b) For an electric motor according to the same scheme - p. 151 Table 7.1 (see figure).
We transfer the found standards in the tables to our PPR schedule
Step 3. For the selected electrical equipment, we need to decide on the number and type of repairs in the coming year . To do this, we need to determine the dates of the last repairs - major and current. Let's say we are making a schedule for 2011. The equipment is operational, we know the dates of repairs . For T-1, a major overhaul was carried out in January 2005, the current one was in January 2008 . For the N-1 pump motor, the major one is September 2009, the current one is March 2010. We enter this data into the chart.
We determine when and what types of repairs the T-1 transformer will undergo in 2011. As we know there are 8640 hours in a year. We take the found service life standard between major repairs for the T-1 transformer, 103680 hours, and divide it by the number of hours in a year, 8640 hours. We calculate 103680/8640 = 12 years. Thus, the next major overhaul should be carried out 12 years after the last major overhaul, and since the last one was in January 2005, which means the next one is planned for January 2017. For current repairs, the operating principle is the same: 25920/8640 = 3 years. The last current repair was carried out in January 2008, so 2008+3=2011. The next routine repair is in January 2011, it is for this year that we draw up a schedule, therefore, in column 8 (January) for the T-1 transformer we enter “T”.
For the electric motor we get; major repairs are carried out every 6 years and are planned for September 2015. The current one is carried out 2 times a year (every 6 months) and, according to the latest current repairs, we plan for March and September 2011. Important note: if the electrical equipment is newly installed, then all types of repairs, as a rule, “dance” from the date of commissioning of the equipment. Our graph looks like this:
Step 4. Determining annual downtime for repairs . For a transformer it will be equal to 8 hours, because in 2011 we planned one routine repair, and in the resource standards for routine repairs the denominator is 8 hours . For the N-1 electric motor, there will be two routine repairs in 2011; the standard downtime for routine repairs is 10 hours. We multiply 10 hours by 2 and get annual downtime equal to 20 hours. In the annual working time column, we indicate the number of hours that this equipment will be in operation minus downtime for repairs. We get the final look of our graph.
Important note: at some enterprises, power engineers in their annual production schedules, instead of the last two columns of annual downtime and annual capital, indicate only one column - “Labor intensity, man*hour”. This labor intensity is calculated by the number of pieces of equipment and the labor intensity standards for one repair. This scheme is convenient when working with contractors performing repair work. Do not forget that repair dates must be coordinated with the mechanical service and, if necessary, the instrumentation service, as well as with other structural units directly related to the repair and maintenance of related equipment. If you have any questions about drawing up the annual PPR schedule, ask questions, I will try, if possible, to answer them in detail.
Distribution of personnel into groups
After selecting the form of service and the structure of the electrical service of the farm, electricians and engineers are distributed among structural units.
The required number of personnel in maintenance and repair groups or at service areas is determined by the formula.
where N x is the number of personnel in the group (at the site, people);
T i - annual labor costs for performing the first type of work in a group (at a site), person/hour;
The number of personnel in the operational (duty) group is determined.
where KD is the coefficient of shared participation of labor costs for operational (duty) maintenance in the planned costs of maintenance, repairs, and equipment
(K D =0.15…..0.25).
The number of personnel in the repair group is determined as
where N repair is the number of personnel in the repair group (persons);
T i - annual labor costs for repairs, man/hour;
F D - actual working time fund per worker, hours.
The number of personnel in the maintenance group is determined
When distributing personnel, it should be taken into account that, according to the requirements of safety regulations for the operation of consumer electrical installations, at least two electricians must be assigned to each site (facility), one of whom is appointed senior.
The total number of electricians in groups (in areas) of the electrical service, determined by labor costs (without major repairs), should not differ sharply from the total number of electricians determined by average load.
Drawing up schedules for electrical equipment maintenance
Requirements for maintenance and repair schedules
The basis for organizing work on the operation of electrical equipment are monthly, quarterly and annual maintenance and repair schedules. When developing them, the following must be taken into account:
TR dates for electrical equipment should be combined with repair dates for the machines on which it is used;
It is advisable to repair electrical equipment used seasonally before the period of its intensive use;
The planned duration of work must correspond to the complexity category of electrical equipment;
The time for electricians to move around service facilities during the working day must be reduced as much as possible;
The entire working day of electricians should be filled with work as much as possible.
The procedure for drawing up maintenance and maintenance schedules
The schedules are drawn up in the following order:
1. A worksheet is developed, on the basis of which a monthly schedule of preventative maintenance is drawn up. The work tables (Appendix 1) provide a list of electrical equipment of individual production divisions of the economy (complex, farm, mechanical repair shops, subsidiary enterprises, etc.) indicating the timing of installation of equipment, carrying out the latest major, current and emergency repairs, maintenance . Each piece of equipment is shown on a separate line.
Maintenance planning begins with a more complex type, i.e. from major repairs, then routine repairs are planned and lastly the time for maintenance is set.
The duration of a particular type of maintenance work is determined by the frequency and date of its last implementation. If the days of repairs fall on Sundays (Saturdays) or pre-holidays, then the repairs are postponed to a later or earlier date
If the dates of maintenance, repair or repair coincide, a more complex type of repair is planned. Calendar days for major equipment repairs are set depending on the specific conditions of the farm or the organization involved. The timing of subsequent maintenance and technical repairs is determined by the frequency of their implementation. If the frequency of scheduled preventative repairs or maintenance is violated, they are scheduled for the beginning of the month.
The type of repair (overhaul, current) or maintenance is indicated in the calendar day columns, respectively, with the letters KR, TR or TO. The table also marks weekends (W) and holidays (P).
2. Based on the worksheet data, a monthly PPR schedule is drawn up (Appendix 2). Using data on the labor intensity of maintenance and repairs, the labor costs of electricians are determined by day to complete the planned amount of work. Repair costs are not taken into account if this type of repair is performed by a third party.
In some cases: with territorial dispersion of units and low labor costs for performing maintenance (0.5-1h) and routine repairs (2-8h); If there is a lack of means of transporting workers, the frequency of routine repairs and maintenance can be neglected. In this case, planning is carried out based on: a full shift workload of electricians (at least two people) and minimal violation of the deadlines for carrying out maintenance work. It is not advisable to violate the frequency of performing maintenance work on electrical equipment operating under conditions of ammonia release in damp rooms.
Schedules for subsequent months are drawn up in the same way.
3. Based on monthly schedules, quarterly and annual schedules are compiled (Appendix 2).
When drawing up general PPR schedules for all departments of the economy, it is necessary to ensure that there is no overlap in the deadlines for work at various facilities for the same services. After drawing up the schedules, they are carefully checked.
To ensure the continuity of technological processes, maintenance and repair of electrical equipment is carried out during technological breaks. Current repairs of electrical equipment are planned simultaneously with routine repairs of process equipment. Seasonal maintenance and repairs, as well as major repairs of electrical wiring of livestock buildings and grain storage areas are planned for the period of their downtime. This work must be completed before the start of the operating season of the production facility.
At the same time, the schedule must ensure: uniform workload of electricians throughout the day, month and year; minimal loss of time for transition and transfers between objects; compliance with the standardized frequency of preventive measures (deviations should not exceed ±35%).
Main stages of PPR equipment
Planned and preventative well-designed repairs include:
Planning;
Preparation of electrical equipment for scheduled repairs;
Carrying out scheduled repairs;
Carrying out activities related to scheduled maintenance and repairs.
The system of scheduled preventive maintenance of equipment includes a couple of stages:
1. Inter-repair phase
Performed without disturbing the operation of the equipment. Includes: systematic cleaning; systematic lubrication; systematic examination; systematic adjustment of electrical equipment; replacement of parts that have a short service life; elimination of minor faults.
In other words, this is prevention, which includes daily inspection and care, and it must be properly organized in order to maximize the service life of the equipment, maintain high-quality work, and reduce the cost of scheduled repairs.
The main work performed during the overhaul phase:
Monitoring the condition of equipment;
Enforcement of appropriate use policies by employees;
Daily cleaning and lubrication;
Timely elimination of minor breakdowns and adjustment of mechanisms.
2. Current stage
Planned preventative maintenance of electrical equipment is most often carried out without disassembling the equipment, only stopping its operation. Includes the elimination of breakdowns that occurred during operation. At the current stage, measurements and tests are carried out, with the help of which equipment defects are identified at an early stage.
The decision on the suitability of electrical equipment is made by repairmen. This ruling is based on a comparison of test findings during routine maintenance. In addition to scheduled repairs, unplanned work is performed to eliminate defects in equipment operation. They are carried out after the entire resource of the equipment has been exhausted.
3. Middle stage
Carried out for the complete or partial restoration of used equipment. Includes disassembly of components intended for viewing, cleaning mechanisms and eliminating identified defects, replacing some quickly wearing parts. The middle stage is carried out no more than once a year.
The system at the middle stage of scheduled preventive maintenance of equipment includes setting the cyclicity, volume and sequence of work in accordance with the regulatory and technical documentation. The middle stage affects the maintenance of equipment in good condition.
4. Major renovation
It is carried out by opening electrical equipment, checking it completely and inspecting all parts. Includes testing, measurements, elimination of identified faults, as a result of which electrical equipment is modernized. As a result of a major overhaul, the technical parameters of the devices are completely restored.
Major repairs are possible only after the inter-repair phase. To carry it out you must do the following:
Draw up work schedules;
Conduct preliminary inspection and verification;
Prepare documents;
Prepare tools and necessary replacement parts;
Carry out fire prevention measures.
Major repairs include:
Replacement or restoration of worn mechanisms;
Modernization of any mechanisms;
Carrying out preventative checks and measurements;
Carrying out work related to the elimination of minor damage.
Malfunctions discovered during equipment testing are eliminated during subsequent repairs. And breakdowns of an emergency nature are eliminated immediately.
PPR systems and its basic concepts
The system of scheduled preventive maintenance of power equipment (hereinafter referred to as the SystemPPREO) is a set of methodological recommendations, norms and standards designed to ensure the effective organization, planning and implementation of maintenance (MOT) and repair of power equipment. The recommendations given in this System of PPR EO can be used at enterprises of any type of activity and form of ownership that use similar equipment, taking into account the specific conditions of their work.
The planned and preventive nature of the EO PPR System is implemented by: carrying out equipment repairs at a given frequency, the timing and logistics of which are planned in advance; carrying out maintenance operations and technical condition monitoring aimed at preventing equipment failures and maintaining its serviceability and performance in the intervals between repairs.
The EO PPR system was created taking into account new economic and legal conditions, and in technical terms, with maximum use of: the capabilities and advantages of the aggregate repair method; the entire range of strategies, forms and methods of maintenance and repair, including new tools and methods of technical diagnostics; modern computing technology and computer technologies for collecting, accumulating and processing information about the condition of equipment, planning repair and preventive actions and their logistics.
The operation of the PPR EO System applies to all equipment of energy and technological workshops of enterprises, regardless of the place of its use.
All equipment operated at enterprises is divided into basic and non-core. The main equipment is the equipment with the direct participation of which the main energy and technological processes of obtaining a product (final or intermediate) are carried out, and the failure of which leads to a cessation or a sharp reduction in the output of products (energy). Non-core equipment ensures the full flow of energy and technological processes and the operation of the main equipment.
Depending on the production significance and functions performed in energy and technological processes, equipment of the same type and name can be classified as either primary or non-core.
The EO PPR system provides that the equipment’s need for repair and preventive actions is satisfied by a combination of various types of maintenance and scheduled equipment repairs, differing in frequency and scope of work. Depending on the production significance of the equipment, the impact of its failures on personnel safety and the stability of energy technological processes, repair actions are implemented in the form of regulated repairs, repairs based on operating hours, repairs based on technical condition, or a combination of them.
Table 5 - number of repairs in 12 months
Table 6 - Planned balance of working time for the year
Payroll ratio
- 1. For discontinuous production =1.8
- 2. For continuous production =1.6
PZ No. 4. Calculation of equipment maintenance schedule.
Task No. 1. The operating time of the pump between major repairs is 8640 hours, medium - 2160 hours, current - 720 hours. The actual number of days of work per year is 360. The number of work shifts is 3, the duration of the shift is 8 hours. By the beginning of the year, the equipment had a mileage after major repairs of 7320 hours, average - 840 hours, current - 120 hours. Draw up a pump maintenance schedule for a year.
Solution.
To draw up a pump maintenance schedule for a year:
1. Number of working days in a month: 360 / 12 = 30 days
2. Month of shutdown for repairs:
Capital (8640 – 7320) / 3 * 8 * 30 = 1.8 months, take February.
Current (2160 – 840) / 3 * 8 * 30 = 1.8 months, take February
RTO (720 – 120) / 3 * 8 * 30 = 0.8 months, we take January.
3. Determine how many months later it is necessary to carry out subsequent repairs:
Capital 8640 / 3 * 8 * 30 = 12 months, we take 12 months, i.e. next year;
Current 2160 / 720 = 3 months, we accept after 3 months, those in February, May, August, November.
RTO 720 / 720 = 1 month, accepted after 1 month, i.e. every month except February, May, August and November.
4. We draw up a PPR schedule for the pump:
Month: Jan. Feb. Mar Apr May June July Aug Sep. Oct. Nov. Dec
View TO TO TO TO TO TO TO TO TO TO
repairs
Task 2. There are 20 dryers in the polyvinyl chloride resin production workshop. The actual operating time of one dryer per year is 6480 hours, the duration of the cycle between repairs is 8640 hours, from major to current repairs is 4320 hours, between repairs and maintenance is 864 hours. The calendar operating time of the equipment per year is 8640 hours. Determine number of overhauls, routine repairs and maintenance of dryers per year.
Methodical instructions.
The required number of repairs per year for each type and type of equipment is determined by the formula:
n repair = Ood.ob. * Tfact * n in. repair / Shopping center, where
Ood.ob. – the number of units of the same type of equipment in operation;
Tts – duration of the overhaul cycle, hour;
Tfact – actual operating time of the equipment, hour;
n in. rem. – the number of all repairs (major, medium, current) of the overhaul cycle.
The number of repairs of each type is determined by the formulas:
capital
n cap. = Tk / Tts
current
n avg. = Tk / Tts.t. - 1
repair and maintenance services
n pto = Tc / Tc.t. - ∑ (drip + current), where
Тк – calendar operating time of the equipment, hour.
Tts.t. – duration of the overhaul period from major to current repairs, hour;
∑ (overhaul + current..) – the sum of capital and current repairs.
Task 3. Calculate the number of compressor repairs based on the following data: number of compressors - 8, duration of the cycle between repairs = 8640 hours, period between overhauls - 7130 hours, between current ones - 2160 hours, between technical repairs - 720 hours. Actual number of days of work per year – 358, number of shifts – 3, shift duration – 8 hours.
Methodical instructions.
To complete the task, use the calculation formulas given in the guidelines for task 2.
Task 4. Draw up a equipment maintenance schedule based on the data given below:
|
Indicators |
Option 1 |
Option 2 |
Option 3 |
|
Equipment |
Compressor |
Dryer |
Autoclave |
|
Operating time between repairs, hours |
|||
|
Capital |
7130 |
14700 |
8238 |
|
Current |
2160 |
2880 |
2880 |
|
RTO |
|||
|
Actual number of working days per year |
|||
|
Number of shifts |
|||
|
Cont. working day, hour |
|||
|
Cont. mileage after repair by the beginning of the year, h. |
|||
|
Capital |
5310 |
12200 |
7310 |
|
Current |
1950 |
||
|
RTO |
Methodical instructions.
To complete the task, use the calculation formulas given in the guidelines for task 1.
Task 5. Determine the equipment downtime for repairs using the data below:
|
Indicators |
Pump |
Distillation column |
Bake |
|
Labor intensity of repairs, person-hours |
|||
|
number |
|||
|
riggers |
|||
|
locksmiths |
|||
|
welders |
|||
|
Working hours |
|||
|
Number of shifts |
Guidelines
Downtime is equal to the quotient of the division: the numerator is the labor intensity of the repair, the denominator is the product of the number of repairmen by the length of the working day and the rate of completion of the norm.
Preventative maintenance is the simplest and most reliable way to plan repair work.
The main conditions ensuring planned preventive relations regarding equipment repair are as follows:
The main need for electrical equipment to be repaired is satisfied by performing scheduled repairs after a specific number of hours worked, thanks to which a periodically repeating cycle is formed;
Each scheduled preventative repair of electrical installations is carried out to the extent necessary to eliminate all existing defects, as well as to ensure the natural operation of the equipment until the next scheduled repair. The period of planned repairs is determined according to the established periods;
The organization of scheduled preventive maintenance and control is based on the usual scope of work, the implementation of which ensures the operational condition of the equipment;
The normal volume of work is determined due to the established optimal periods between scheduled periodic repairs;
Between scheduled periods, electrical equipment undergoes scheduled inspections and checks, which are a means of prevention.
The frequency and alternation of scheduled equipment repairs depends on the purpose of the equipment, its design and repair features, dimensions and operating conditions. Preparation for scheduled repairs is based on identifying defects, selecting spare parts and spare parts that will need to be replaced during repairs. An algorithm for carrying out this repair is specially created, which ensures uninterrupted operation during repairs. This approach to preparation makes it possible to carry out complete repairs of equipment without disrupting the usual production operations.
Planned and preventative well-designed repairs include:
Planning;
Preparation of electrical equipment for scheduled repairs;
Carrying out scheduled repairs;
Carrying out activities related to scheduled maintenance and repairs.
The system of scheduled preventive maintenance of equipment includes a couple of stages:
1. Inter-repair phase
Performed without disturbing the operation of the equipment. Includes: systematic cleaning; systematic lubrication; systematic examination; systematic adjustment of electrical equipment; replacement of parts that have a short service life; elimination of minor faults.
In other words, this is prevention, which includes daily inspection and care, and it must be properly organized in order to maximize the service life of the equipment, maintain high-quality work, and reduce the cost of scheduled repairs.
The main work performed during the overhaul phase:
Monitoring the condition of equipment;
Enforcement of appropriate use policies by employees;
Daily cleaning and lubrication;
Timely elimination of minor breakdowns and adjustment of mechanisms.
2. Current stage
Planned preventative maintenance of electrical equipment is most often carried out without disassembling the equipment, only stopping its operation. Includes the elimination of breakdowns that occurred during operation. At the current stage, measurements and tests are carried out, with the help of which equipment defects are identified at an early stage.
The decision on the suitability of electrical equipment is made by repairmen. This ruling is based on a comparison of test findings during routine maintenance. In addition to scheduled repairs, unplanned work is performed to eliminate defects in equipment operation. They are carried out after the entire resource of the equipment has been exhausted.
3. Middle stage
Carried out for the complete or partial restoration of used equipment. Includes disassembly of components intended for viewing, cleaning mechanisms and eliminating identified defects, replacing some quickly wearing parts. The middle stage is carried out no more than once a year.
The system at the middle stage of scheduled preventive maintenance of equipment includes setting the cyclicity, volume and sequence of work in accordance with the regulatory and technical documentation. The middle stage affects the maintenance of equipment in good condition.
4. Major renovation
It is carried out by opening electrical equipment, checking it completely and inspecting all parts. Includes testing, measurements, elimination of identified faults, as a result of which electrical equipment is modernized. As a result of a major overhaul, the technical parameters of the devices are completely restored.
Major repairs are possible only after the inter-repair phase. To carry it out you must do the following:
Draw up work schedules;
Conduct preliminary inspection and verification;
Prepare documents;
Prepare tools and necessary replacement parts;
Carry out fire prevention measures.
Major repairs include:
Replacement or restoration of worn mechanisms;
Modernization of any mechanisms;
Carrying out preventative checks and measurements;
Carrying out work related to the elimination of minor damage.
Malfunctions discovered during equipment testing are eliminated during subsequent repairs. And breakdowns of an emergency nature are eliminated immediately.
Each individual type of equipment has its own frequency of scheduled preventive maintenance, which is regulated by the Technical Operation Rules. All activities are reflected in the documentation, strict records are kept of the availability of equipment, as well as its condition. According to the approved annual plan, a nomenclature plan is created, which reflects the implementation of major and current repairs. Before starting current or major repairs, it is necessary to clarify the date of installation of electrical equipment for repairs.
Yearly schedule of preventative maintenance- this is the basis that serves to draw up a plan and estimate for the year, developed 2 times a year. The annual budget amount is divided into months and quarters, it all depends on the period of major repairs.
Today, for the system of scheduled preventive maintenance of equipment, computer and microprocessor technology (structures, stands, installations for diagnostics and testing) are most often used, which affects the prevention of equipment wear, reduction of repair costs, and also helps to increase operating efficiency.
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