The main document according to which the repair of electrical equipment is carried out 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.” Let's use the reference book by A.I. FMD 2008.
Let's look at a specific example. Let's assume that in our electrical department, in building 541, we have:
1. Three-phase two-winding oil transformer 6/0.4 kV,
2. Pump electric motor, asynchronous Рн=125 kW;
Step 1. We enter our equipment into the empty form of the table “Initial data for drawing up a PPR schedule.”
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 the table “Initial data for drawing up a maintenance schedule.”
b) For an electric motor according to the same scheme - page 151 Table 7.1 (see figure).
We transfer the found standards in the tables to the table “Initial data for drawing up a PPR schedule.”
Table. - Initial data for drawing up a PPR schedule
Regular inspections of electrical equipment (without turning them off) are carried out once a month. The duration and labor intensity of maintenance of electrical equipment should be 10% of current repairs.
In order to determine how long the repair will last in months, it is necessary to divide the number of hours of equipment repair frequency by the number of hours per month. We make the calculation for transformer T-1: 103680/720 = 144 months.
Step 3. After the table “Initial data for drawing up a maintenance schedule,” it is necessary to calculate the number of repairs between inspections and create a repair cycle structure for each type of equipment.
Step 4.
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 2014. The equipment is operational, the dates of repairs are known to us. For the T-1 transformer, major repairs were carried out in January 2008, the current one was carried out in January 2011. For the N-1 electric motor, the capital one is September 2012, the current one is March 2013.
We determine when and what types of repairs the T-1 transformer will undergo in 2014. As we know there are 8640 hours in a year. We take the found resource standard between major repairs for transformer T-1 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 2008, which means the next one is planned for January 2020.
For current repairs, the operating principle is the same: 25920/8640 = 3 years. The last current repair was carried out in January 2011, so 2011+3=2014. The next routine repair is in January 2014, 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 2018. 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 2014.
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.
Step 5. We determine the annual downtime for routine repairs. For a transformer it will be equal to 8 hours, because in 2014, we planned one routine repair, and the resource standards for routine repairs are 8 hours. For the N-1 electric motor, there will be two routine repairs in 2014; the standard downtime for routine repairs is 10 hours. Multiply 10 hours by 2 and get annual downtime equal to 20 hours .
Step 6. We determine the annual labor intensity of repairs.
For a transformer it will be equal to 62 people/hour, because in 2014, we planned one current repair, and the resource standards for current repairs are 62 people/hour. For the N-1 electric motor, there will be two routine repairs in 2014, the labor intensity for routine repairs is 20 people/hour. We multiply 20 people/hour by 2 and get the annual labor intensity - 40 people/hour.
Our graph looks like this:
Step 7 Based on the structure of the repair cycle for each equipment, we indicate the number of inspections between repairs and determine the annual downtime for maintenance.
For one transformer, the downtime will be 0.8 hours; according to the structure of the repair cycle, the number of inspections between repairs is 35 maintenance. In 2014, we planned one routine repair, so the number of inspections will be only 11, the annual maintenance downtime rate will be 8.8 (11 multiplied by 0.8).
For the N-1 electric motor, the downtime will be 0.1 hours; according to the structure of the repair cycle, the number of inspections between repairs is 5 maintenance. In 2014, we planned two routine repairs, so the number of inspections will be 10, the annual maintenance downtime rate will be 1.0 (10 multiplied by 0.1).
Labor intensity is calculated by the number of pieces of equipment and the labor intensity of one repair. For a transformer it will be equal to 68.2 people/hour (6.2 people/hour multiplied by 11TO).
For the N-1 electric motor in 2014 it will be equal to 20 people/hour (2 people/hour multiplied by 10 TO).
We get the final look of our graph.
This scheme is convenient when working with contractors performing repair work. Do not forget that the dates of repairs must be coordinated with the mechanical service and, if necessary, the instrumentation service, as well as with other structural divisions directly related to the repair and maintenance of related equipment.
Table 6.1., column 9, line “Total”.
Table 6.6., PPR schedule, column 19, line “Total”.
Table 6.1., column 4, line “Total”.
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 disrupting equipment operation. 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;
Conducting employees to follow appropriate use guidelines;
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 renovation includes:
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 that are of an emergency nature are eliminated immediately.
PPR systems and its basic concepts
The system for scheduled preventive maintenance of power equipment (hereinafter referred to as the SystemPPREO) is a complex methodological recommendations, norms and regulations designed to ensure effective organization, planning and carrying out maintenance (TO) 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 PPR EO system was created taking into account new economic and legal conditions, and in technically-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 computer technology And computer technology 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 enterprises, regardless of the place of its use.
All equipment operated at enterprises is divided into main 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 the energy and technological processes equipment of the same type and name can be classified as both primary and non-main.
The EO PPR system provides that the equipment’s need for repair and preventive actions is satisfied by a combination various types Maintenance and scheduled repairs of equipment, 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
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