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 “System” reference book. Maintenance and repair energy 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 a little general information, what is the annual PPR schedule.
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, symbol indicate 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've looked at 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 column of the annual working time fund 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 carrying out 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 divisions 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.
Preventive maintenance is the simplest and most reliable way of planning repair work.
The main conditions ensuring planned preventive relations regarding equipment repair are as follows:
The main need for repairs of electrical equipment is satisfied by repairs performed after a specific number of hours worked. scheduled repairs, due 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 natural work 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 implement complete renovation equipment without disrupting normal 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 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 and preserve quality work, reduce costs for planned 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 preventive 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
It is 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. 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 major repairs, complete restoration occurs technical parameters devices.
Major repairs are possible only after the interrepair 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.
Every separate species equipment has its own frequency of scheduled preventive maintenance, which is regulated by the Rules technical operation. 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.
Today, scheduled preventive maintenance is the simplest, but at the same time reliable method implementation of work. As for the resumption of operation of the equipment, the list of basic conditions ensuring it includes the following:
The units have already worked a specific number of hours and a new periodic operating cycle is coming, which must necessarily precede scheduled preventive maintenance.
The normal level of repair work is clearly indicated by defining optimal periods between scheduled periodic maintenance.
Organization of approved work. Control over them is based on standard volume works Their responsible implementation ensures the continued full functioning of existing units.
Scheduled preventive maintenance of electrical installation equipment is carried out to the extent necessary to effectively eliminate all existing defects. It is also carried out to ensure the natural course of operation of the equipment until subsequent repairs. Typically, a planned preventive maintenance schedule is drawn up taking into account established periods.
During breaks between scheduled repair work, electrical equipment is also subject to pre-scheduled inspections and a number of checks, which are essentially preventive.
Repair work of electrical equipment
The alternation and frequency of scheduled repairs of units depend both on their purpose and on their design features, operating conditions, dimensions. The basis of preparation for this work is to clarify defects, select spare parts and spare parts that will need to be replaced in the future. An algorithm for performing this type of manipulation is specially developed, making it possible to ensure uninterrupted operation of equipment (machines) during repairs. Proper preparation Such an action plan makes it possible to completely restore the functioning of all devices without disrupting the usual operating mode of production.
Organization of the process
Competent planned preventive maintenance involves the following sequence:
1. Planning.
2. Preparing units for repair.
3. Carrying out repair work.
4. Carrying out activities related to repairs and scheduled maintenance.
The system of planned preventive maintenance of equipment under consideration has stages: between repairs, current. They can be considered in more detail.
Interrepair stage
The between-repair phase allows for equipment repair work to be carried out without disturbing production process. It includes systematic cleaning, lubrication, inspection, and adjustment of units. This also includes eliminating minor faults and replacing parts with a short service life. In other words, this is prevention, which cannot be done without daily examination and care. It must be properly organized in order to maximize the service life of existing equipment.
A serious approach to this issue can significantly reduce the costs of future repairs and contribute to better and more efficient implementation of the tasks set by the enterprise. The main work that is carried out during the overhaul phase is daily lubrication and cleaning of units, compliance by all employees with the rules for using devices, monitoring the current condition of equipment, adjusting mechanisms and timely elimination of minor breakdowns.
Current stage
This stage of scheduled preventive maintenance of electrical equipment often does not involve disassembling the devices, but it includes the prompt elimination and elimination of all breakdowns that arose during the period of operation. In this case, only the units stop. During the current stage, tests and measurements are carried out, thanks to which equipment flaws are identified even at an early stage, and this is very important.
The decision about whether electrical equipment is suitable is made by repair specialists. This is within their competence. They base their decision on a comparison of the existing conclusions obtained during tests during the implementation of planned ongoing repair work.
Elimination of defects in the functioning of units can be carried out not only during scheduled repairs, but also outside of it. This usually happens after the equipment resource has completely exhausted itself.
Carrying out scheduled preventative maintenance: middle stage
Allows you to partially or completely restore worn-out units. The stage includes disassembling the necessary components to view them, eliminating identified defects, cleaning mechanisms and replacing some quickly wearing parts and components. It is held annually.
The system of scheduled preventive maintenance at the middle stage includes setting the volume, cyclicity and sequence of the work indicated here in strict accordance with all regulatory and technical documents. Thanks to this, normal operation of the equipment occurs.
Major repairs and its prerequisites
It is carried out after opening the equipment and thoroughly checking it, examining all parts for defects. IN this stage includes measurements, tests, elimination of identified faults that require modernization of units. Here, a 100% restoration of the technical parameters of the devices in question takes place.
When is a major overhaul of electrical equipment carried out?
This kind of manipulation is possible only after the completion of the overhaul phase. The following conditions must also be met:
A work schedule has been drawn up.
A preliminary check and inspection has been carried out.
All necessary documents have been prepared.
Replacement parts and tools provided.
Fire safety measures have been completed.
What does a major renovation include?
The process of repairing electrical equipment in in this case comprises:
1. Replacement/restoration of worn mechanisms.
2. Upgrades of devices that require this.
3. Carrying out measurements and preventive checks.
4. Carrying out work to eliminate minor damage.
Malfunctions and defects that are discovered during inspections of equipment (machines) are eliminated during subsequent repairs. Failures classified as emergencies are repaired immediately. Equipment different types has its own frequency of activities related to repair work, which is regulated by the rules of technical operation. All manipulations carried out are reflected in the documentation; strict records are kept of the availability of units and their condition.
According to the approved plan for the year, a nomenclature plan is created, which records the implementation of current/major repairs. Before starting work, the date of shutdown of electrical equipment (machines) for repairs must be specified.
The schedule of planned preventive maintenance is the official basis for drawing up an annual budget plan, developed twice during the specified period. The total amount of the estimate plan is distributed by month and quarter, taking into account the period of capital repair work.
Peculiarities
Today, the preventive maintenance system involves the use of microprocessor and computer technology (stands, structures, testing and diagnostic installations). Thanks to this, equipment wear is prevented and restoration costs are reduced. Also, all this helps to increase operational efficiency, and consequently, the profit of enterprises.
Preventative maintenance: drawing up a schedule for the year
Let's look at how the schedule for the year is drawn up. Scheduled preventive maintenance of buildings or electrical equipment is a full-fledged set of organizational and technical measures closely related to supervision and maintenance. It concerns all types of repairs and is carried out periodically according to a previously drawn up plan. This helps prevent premature partial or complete wear of equipment and accidents. All systems fire protection are in constant readiness.
Scheduled preventive maintenance is organized according to a system that includes such types of maintenance as:
Weekly technical repairs.
Monthly repair work.
Annual pre-scheduled preventative maintenance.
The developed regulations on scheduled preventive maintenance are approved by line ministries, as well as departments. The document is mandatory for execution by industry enterprises.
Preventive maintenance is always carried out in strict accordance with the existing annual work schedule, which includes each mechanism subject to routine or major repairs. When drawing up this schedule, standards for the frequency of equipment maintenance are used. They are taken from the passport data of the units prepared by the manufacturer. All available mechanisms and devices are included in the schedule, which indicates brief information about them: quantity, resource standards, labor intensity of one current or major repair. It also records information about the latest ongoing and major repairs.
Additional Information
The regulations on preventive maintenance contain information on intra-shift maintenance (supervision, care) and preventive inspection of existing equipment. It is usually assigned to operational and duty personnel. It also contains information about the implementation of planned work.
The advantages of planned preventive maintenance systems include:
Recording downtime of units, equipment, machines.
Control over the duration of the between-repair periods of operation of devices.
Forecasting the costs of repairing equipment, mechanisms, components.
Accounting for the number of personnel involved in the activity, which depends on the complexity of repairs.
Analysis of the causes of equipment failure.
Disadvantages of planned preventive maintenance systems:
The complexity of calculating labor costs.
Lack of convenient and suitable tools for planning (implementing) repair activities.
Difficulty in taking into account the parameter/indicator.
The complexity of operational adjustment of planned work.
Each preventative maintenance system has a trouble-free model for the operation/repair of units, but in the event of accidents or as a result of wear and tear, unscheduled work may also be carried out related to the full restoration of the functioning of the devices.
The frequency of equipment shutdowns for major or routine repairs is determined by the service life of wear-out mechanisms, parts, and assemblies. And their duration is determined by the time needed to perform the most labor-intensive manipulations.
Lifting machines (units), in addition to routine inspection, are also subject to technical examination. It is carried out by specialists responsible for the supervision of this equipment.
The PPR system is based on the following basic principles:
preventive work must be carried out strictly according to pre-drawn calendar schedules;
when justifying the frequency of preventive maintenance, it is necessary to take into account environmental conditions, temporary operating modes of equipment, the degree of responsibility of technological processes, etc.;
the volume and labor intensity of the preventive work performed are provided on an average basis (enlarged) and in each specific case are specified depending on the technical condition of the equipment;
the design of the equipment must comply with environmental conditions and operating modes, based on the requirements of regulatory documents.
Scheduled preventive maintenance is a set of works aimed at maintaining and restoring the performance of equipment. Depending on the nature and degree of wear of the equipment, on the volume, content and complexity of preventive work, it includes inter-repair maintenance, current, medium and major repairs.
Inter-repair maintenance is preventive in nature. It consists of regular cleaning and lubrication of equipment, inspection and testing of the operation of its mechanisms, replacement of parts with short term services, troubleshooting minor problems. These works, as a rule, are performed without stopping the equipment during its current operation.
Current repairs are a set of repair work carried out between two major overhauls and consisting of the replacement or restoration of individual parts. Current repairs are carried out without completely disassembling the equipment, but it requires a short-term shutdown and removal of the equipment from operation with stress relief. During routine repairs of equipment, external inspection, cleaning, lubrication, checking the operation of mechanisms, repairing broken and worn parts are carried out, for example, inspecting and cleaning a generator without removing the rotor, varnishing the frontal parts, wiping insulators, inspecting and cleaning the inputs of transformers and switches without changing them. etc.
Thus, routine repairs are performed to ensure or restore the operability of electrical equipment by eliminating failures and malfunctions that arise during its operation. During current repairs the necessary measurements and tests are carried out to identify equipment defects at an early stage of their development. Based on measurements and tests, the scope of the upcoming major overhaul is determined. Current repairs are usually carried out at least once every 1–2 years.
During a medium repair, individual components are disassembled for inspection, cleaning of parts and elimination of detected faults, repair or replacement of wear parts or components that do not ensure normal operation of the equipment until the next major overhaul. Average repairs are carried out at intervals of no more than once a year.
During a major overhaul, equipment is opened and inspected with a thorough internal inspection, measurements of technical parameters and elimination of detected faults. Major repairs are carried out at the end of the overhaul period established for each type of equipment. During final repairs, all worn parts are replaced or restored, and individual elements and components of equipment are modernized. These works require disassembly of units, complete external and internal repairs with checking the condition of components and parts, a significant number of highly qualified workers, long-term shutdown of electrical equipment, a large amount of testing and complex devices. The main electrical equipment undergoes major overhauls within a certain period of time.
Unlike current repairs, medium and capital repairs are aimed at restoring partially or completely used up mechanical and switching life of equipment.
Upon completion of the repair, equipment assembly, adjustment and testing are carried out. After preliminary acceptance from repair, the main equipment of power plants and substations is checked in operation under load for 24 hours.
A conclusion about the suitability of equipment for operation is made based on a comparison of test results with current standards, the results of previous tests, as well as measurements obtained on the same type of equipment. Non-transportable equipment is tested in mobile electrical laboratories.
In addition to scheduled preventative repairs, in the practice of power supply systems, unplanned repairs take place: emergency repairs and unscheduled ones. The task of emergency repair is to eliminate the consequences of an accident or eliminate damage that requires immediate shutdown of equipment. In emergency circumstances (fire, insulation failure, etc.), the equipment is stopped for repairs without the permission of the dispatcher.
The timing of major repairs of the main equipment of power facilities is as follows:
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Turbogenerators up to 100 MW Turbogenerators over 100 MW Hydro generators Synchronous compensators Main transformers, reactors and auxiliary transformers Oil switches Load switches, disconnectors, grounding blades Air circuit breakers and their drives Compressors for air circuit breakers Separators and short circuiters with drives Capacitor installations Rechargeable batteries |
Once every 45 years Once every 3–4 years Once every 4–6 years Once every 4–5 years The first time no later than 8 years after putting it into operation, subsequently - as needed, depending on the results of measurements of their condition Once every 6–8 years Once every 4–8 years Once every 4–6 years Once every 2–3 years Once every 2–3 years Once every 6 years No later than 15 years after the start of operation |
Unscheduled repairs are agreed upon with the system dispatcher and submitted with a corresponding application. They are carried out to eliminate various malfunctions in the operation of equipment, as well as after the switching resource has expired. Thus, depending on the type, circuit breakers with voltages of 6 kV and higher are subject to unscheduled repairs after a shutdown of 3–10 short circuits at rated breaking current.
ensure timely and high-quality performance of maintenance, scheduled maintenance (PPR) and preventive electrical installations;
Let's consider the concept of scheduled preventive maintenance (PPR) of electrical installations.
Scheduled preventive maintenance is a specific system of work to maintain electrical equipment and other elements of electrical installations in normal (working) condition.
Preventative maintenance system (PPR system) electrical equipment provides for between-repairs maintenance, current, medium and major repairs.
- Overhaul maintenance includes:
1. operational maintenance - cleaning, lubrication, wiping, regular external inspection, etc.;
2. minor repairs electrical equipment - fixing small parts, fastening parts, tightening loose fasteners.
- Current repairs of electrical installations include:
1. replacement of quickly wearing parts.
2. correction of minor defects, flushing and cleaning of oil and cooling systems.
During the period of routine repairs, the condition of electrical equipment and the degree of need on average and major repairs, adjust the originally planned repair dates.
Current repairs are carried out at the installation site of electrical equipment.
For electric motors are being implemented following operations:
1. external inspection and wiping of the electric motor from dust, oil and dirt;
2. check:
shields for clamps;
radial and axial clearances;
rotation of the lubricating ring;
electric motor mountings;
3. presence of lubricating oil in bearings;
4. restoration of insulation at jumpers and output ends;
5. checking the serviceability of grounding, belt tension, correct selection fuse links;
6. measuring the insulation resistance of the windings with a megger.
For ballasts you need:
1. external inspection and wiping;
2. cleaning burnt contacts;
3. adjustment of the pressure of sliding contacts;
4. check:
a) contacts in connections;
b) operation of the magnetic circuit;
c) contact tightness;
d) relay or thermocouple settings;
5. adjustment of springs and operation of the mechanical part;
6. checking the correct grounding of the device.
- Medium repair of electrical installations.
Medium repairs include partial disassembly of electrical equipment, disassembly of individual components, repair or replacement of worn parts, measurement and determination of the condition of parts and components, drawing up a preliminary list of defects, making sketches and checking drawings for spare parts, checking and testing electrical equipment or its individual components.
Medium repairs are carried out at the installation site of electrical equipment or in a repair shop.
For electric motors perform all routine repair operations; in addition, it is provided:
1. complete disassembly electric motor with the elimination of damaged parts of the winding without replacing it;
2. flushing mechanical parts electric motor;
3. washing, impregnation and drying of windings;
4. coating of windings with varnish;
5. checking the serviceability and fastening of the fan;
6. if necessary, grooving the rotor shaft journals;
7. checking and aligning gaps;
8. change of flange gaskets;
9. washing the bearings and, if necessary, refilling the bearing shells;
10. welding and sharpening of sharpening points at electric motor panels;
11. Electric motor assembly with testing at idle and operating strokes.
For ballasts perform all routine repair operations, in addition, the following is provided:
1. complete replacement all worn parts of the device;
2. checking and adjusting relays and thermal protection;
3. repair of casings, painting and testing of equipment.
- Major renovation.