EE 81 Course Pack - Maintenance of Electrical Equipment and Devices - University of the Philippines PDF

University of the Philippines Los Baños College of Engineering and Agro-industrial Technology Department of Electrical Engineering EE 81 Course Pack Maintenance of Electrical Equipment and Devices First Semester A.Y. 2024-2025 Prepared by: GYR Garcia & GMM...

University of the Philippines Los Baños College of Engineering and Agro-industrial Technology Department of Electrical Engineering EE 81 Course Pack Maintenance of Electrical Equipment and Devices First Semester A.Y. 2024-2025 Prepared by: GYR Garcia & GMM Gonzales  MODULE 1 Welcome to EE 81 2S2324! In this module, you will learn about the Overview of Electrical Maintenance Strategies and the background on Electric Preventive Maintenance (EPM). Common knowledge tells us that everything we buy will eventually deteriorate (except for land and housing properties). For example, the new car that you bought will lose its value and reduce its performance over time. The same notion goes with the use of electrical equipment. Once installed, proper maintenance must be conducted in order to uphold its integrity, operational functionality, and efficiency. The main challenge in using electrical equipment in a power system (a complex assembly of equipment and devices for the generation, transmission, and distribution of energy) is that the load is variable. This may affect the overall performance of your system that includes the selection of equipment, protective elements, and coordination devices. With proper maintenance of these equipment, unanticipated hazards and failure of operation can be mitigated as early as possible. Electrical maintenance and strategies do not only cover the protection of our equipment but of our personnel and other properties. Thus, almost every industry has a maintenance department to ensure that the said strategies are implemented effectively. Some of the programs included in the routine maintenance are as follow: Routine inspections Service of electrical apparatus Routine tests Service of control wirings Repairs Benefits of a Proper Maintenance Program Minimizes accidents Reduces unplanned shutdowns Extends mean time between failures of your equipment These benefits could also be classified as direct or indirect. Direct: reduced cost of repairs reduced downtime of equipment improved safety of personnel and property Indirect: improved morale of employees better workmanship increased productivity early discovery of deficiencies in the system EE 81 Course Pack First Semester A.Y. 2024-2025 A guiding principle for an effective maintenance program for the installed equipment is also shown on the figure below: Dry and free from water Cool temperature Clean surroundings Airtight Check your surroundings or your home. Are the guiding principles for Something to an effective maintenance of equipment and electrical devices ponder on: followed? If not, how can you improve it? Approaches to Electrical Maintenance 1. Reactive Maintenance This has two approaches; the first one is commonly known as Run-to-Failure (RTF). This is probably one of the most traditional approaches to electrical maintenance. It is also not commonly used since a ‘maintenance’ is not really conducted. This because only when the equipment has affected the performance of the system will it be repaired or replaced. The advantage of RTF is that it is less costly in terms of variable costs and applicable to noncritical applications. The disadvantage is that it can be more expensive in the long run, riskier, higher probability of performance failure, and lower power reliability. This is usually employed in small organizations and utilities with less manpower. The second one is “inspect and service as necessary”. This approach still falls on the traditional approach, but it is more progressive than RTF. It employs a regular schedule of equipment inspection. The advantage of this is that problems are usually mitigated before they become catastrophic. The disadvantage is that the monitoring is still considered as an informal way of foreseeing failures. This is usually employed by small to medium industrial plants. Reactive maintenance:  Functional failure prompts repair or replacement of equipment  Causes delay in operation  Inefficient use of workforce Examples include the replacement of failed fuses, incandescent lamps, and repair equipment EE 81 Course Pack First Semester A.Y. 2024-2025  2. Preventive Maintenance Scheduled preventive maintenance (PM) also known as Time-based Maintenance (TBM). The maintenance activities follow a more cohesive routine as compared to the “inspect and service as necessary” approach. PM activities are conducted at a more regular intervals or operational cycles. The advantage of PM is that maintenance results are compared to manufacturer’s recommendations or industry standards. The disadvantage of this approach is that it does not necessarily connect the PM results with the performance of the whole system, or in other words, it does not optimize the system. It is used in more sophisticated industries where safety and productivity are considered important. Preventive maintenance:  Involves regular inspection, cleaning, adjustments, parts replacement, and repair  Can cause unnecessary maintenance  High costs Example is overhauling a properly functioning motor generator set 3. Predictive Maintenance Also known as Condition Based Maintenance (CBM). It is similar to TBM but uses nonintrusive testing techniques. The maintenance program includes the equipment’s performance history and maintenance data. It is also used in sophisticated industries like in TBM. Predictive maintenance:  Uses nonintrusive techniques, visual inspection, and historical data analysis  Used for planning schedule of operation and shutdowns  Not applicable to all equipment Example is the detection of high-resistance electrical connections by infrared thermography 4. Proactive Maintenance Proactive maintenance aims to anticipate failures or defects and introduce solutions before they occur. It also aims to identify the root cause of the problem in order to correct them before a major or minor breakdown of the equipment. Proactive maintenance:  Repairing of symptoms before they become an “illness”  High costs  Economically, efficiently, and quickly determines the cause of the problem  Reduces the recurrence of the problem  Long term solutions EE 81 Course Pack First Semester A.Y. 2024-2025  5. Reliability Centered Maintenance (RCM) This approach integrates equipment condition, criticality, performance and failure history, and life cycle costs in developing a maintenance program. It periodically assesses the condition of all the equipment used. The advantage of RCM is that it is a combination of reactive, preventive, predictive, and proactive maintenance methods. It can also quantify the risks involved without interrupting the operation of the equipment. The disadvantage of this is that it is the most expensive approach due to the high level of expertise needed from personnel in order to execute the maintenance program. Source: Adapted from St. Germain, E. and Pride, A., NASA Facilities RCM Guide, 1996, p. 1-1. Recommended steps to implement an effective maintenance program: 1. Set the short term and long-term objectives/goals 2. Collect data on equipment failures 3. Identify criticalities of the equipment 4. Determine the risks that can be permitted or not 5. Set up key performance indicators (KPIs) 6. Determine maintenance techniques that are within the capability of the system 7. Employ the most critical and fastest strategies in implementation stage 8. Consolidate data 9. Repeat EE 81 Course Pack First Semester A.Y. 2024-2025 To end the first part of this module, here’s an example of a decision logic tree in formulating a maintenance strategy. Source: Adapted from St. Germain, E. and Pride, A., NASA Facilities RCM Guide, 1996, p. 2-3. Seatwork Could you think of a device that you use in your daily activities and design a corrective maintenance (CM) strategy in order to prolong its useful life? EE 81 Course Pack First Semester A.Y. 2024-2025  Electric Preventive Maintenance (EPM) After learning about the overview of maintenance strategies, we now go to the second part of the module which is the Electric Preventive Maintenance (EPM). We’ll discuss more about this in the next module but let’s take a look on the key factors affecting EPM decisions. 1. Safety impact 5. Failure predictability 2. Productivity and profitability 6. Likelihood of damage impact of equipment failure 7. Technical support 3. Costs 8. Resource availability 4. Life expectancy of equipment An EPM should be conducted under management supervision in accordance with standards and by experienced and trained EPM personnel. It is then important that EPM personnel have the knowledge and background on the fundamentals of electrical power technology, general maintenance techniques, and the design and operation of the equipment. An indicator of a high quality EPM program is the ability to trend test results. Examples include insulation resistance, leakage current, capacitance, PF, and dissipation factor (DF); bearing temperature and vibration; and winding temperature. As mentioned in the first part of the module, equipment degradation is expected to occur especially towards the end of its useful life. If failure of operation already occurs, then these steps could be done: Conduct a failure-cause analysis  Compare present failures to past conditions.  If no root cause is identified, resume operation and continue monitoring the performance of the equipment and the system.  If the problem is endemic, inform the manufacturer of the equipment right away.  If the problem is plant-specific, check the plant design, operational stats, and environmental factors.  Further identify the specific deficiency.  Determine the deficiencies in the problem.  Perform post-monitoring and testing. Once the problem has been mitigated, a post maintenance testing serves as the final procedure of the entire EPM program. This is heavily emphasized in highly sophisticated plants and industries to ensure the reliability and continuity of operations. EE 81 Course Pack First Semester A.Y. 2024-2025  Before we end this module, here’s another seatwork for you to work on. Use the same device that you used in the first seatwork and create a Seatwork step-by-step procedure that could be done if a failure of operation has occurred. Good job! You’ve finished Module 1. See you next week for the next module which will be about the Planning and Overview of EPM Procedures. Padayon! --End of Module 1-- EE 81 Course Pack First Semester A.Y. 2024-2025 "Exclusively for First Semester A.Y. 2024-2025 students use only. This material has been reproduced and communicated to you by or on behalf of University of the Philippines pursuant to PART IV: The Law on Copyright of Republic Act (RA) 8293 or the “Intellectual Property Code of the Philippines”. The University does not authorize you to reproduce or communicate this material. The Material may contain works that are subject to copyright protection under RA 8293. 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