Have you ever wondered about the importance of an equipment maintenance plan and why is it necessary in Electrical power systems?
Today, we will talk in detail about the planned maintenance of electrical equipment and its importance. A maintenance plan covers a facility's routine maintenance, as well as the long term care of certain equipment or power systems inside of a facility.
In order to know about the details, you must first know about the definition of "Equipment Maintenance plan".
According to the NFPA (National Fire Protection Association);
"Electrical equipment maintenance plan (EMP) is the practice of conducting routine inspections, tests, and the servicing of electrical equipment so that impending troubles can be detected and reduced or eliminated."
Electrical equipment malfunctions and failures are responsible for million-dollar losses to facilities, industries, and businesses worldwide. As equipment starts to display signs of electrical aging, it should act as a trigger for the employer or owner to carry out preventive maintenance to avoid catastrophic failure.
The NFPA 70B signifies the importance of having an effective equipment maintenance plan.
As per Article 4.1.1 of the NFPA 70B, 2016:
"As soon as new equipment is installed; a process of normal deterioration begins. Unchecked, the deterioration process can cause malfunction or an electrical failure.
Deterioration can be accelerated by factors such as a hostile environment, overload, or severe duty cycle. An effective EMP identifies and recognizes these factors and provides measures for coping with them."
Scheduled routine maintenance can significantly increase the lifespan and reduce their failure rate for all types of electrical equipment, which can be achieved by having a proper maintenance program.
A well-administered maintenance plan will reduce accidents, save working personnel's lives and minimize costly breakdowns and unplanned shutdowns of production equipment.
The NFPA 70B provides general guidelines for the implementation of a useful maintenance plan by breaking it down into six (06) major categories.
Hello there! We had previously written a blog about the Importance of Arc Flash Hazard Analysis. If this piques your interest, check it out and let us know what you think
All kinds of electrical equipment eventually begin to portray symptoms from aging. An effective maintenance plan can reduce the downtime of the facility by scheduling proper outages coinciding with routine maintenance activities. For the safety of the equipment as well as the personnel on-site, OSHA recommends regular preventive maintenance for the equipment being operated under hazardous conditions.
As per Article 1926.431 of the NFPA 70B, 2016:
"The employer shall ensure that all wiring components and utilization equipment in hazardous locations are maintained in a dust-tight, dust-ignition-proof, or explosion-proof condition, as appropriate".
A well thought out EMP can save lives, reduce equipment failure, and prevent unplanned shutdowns in addition to enhancing site safety in the long run. This in turn increases productivity and boosts employee morale.
In-depth maintenance programs tend to not only improve the life of the equipment but also correct additional causes responsible for equipment degeneration. These include improper protective device settings, incorrect transformer taps voltages, loading variations among others.
An equipment maintenance plan has a defined set of requirements as per NFPA 70B which are critical for effective implementation.
Article 5.1 of the NFPA 70B, 2016 explains the criteria for an effective equipment maintenance plan:
"An effective electrical equipment maintenance plan (EMP) program should enhance safety and also reduce equipment failure to a minimum consistent with good economic judgment."
In addition to the above set of requirements, the context in which the prescribed equipment is being operated upon should be considered as well. Each scenario under normal and operating conditions is required to be studied carefully to determine worst-case conditions separately for each equipment.
The following basic factors should be considered before planning an Equipment Maintenance Program (EMP).
Will an equipment failure endanger or threaten the safety of any personnel in the facility? What can be done to ensure personnel safety of all workers?
Is installed equipment (both electrical and mechanical) so unique that required repairs would be unusually expensive?
Will breakdown repairs or replacement of failed equipment require extensive downtime? How much production money will be lost in the event of an equipment failure? Which equipment is most vital to production?
The appointment of highly trained and qualified personnel for the implementation of the maintenance program carries paramount importance. The person should be experienced in administrative policies and have a solid command over the management of maintenance personnel.
They are required to be in leadership roles and be able to set specific objectives (both short and long term) with realistic target dates.
As per Article 188.8.131.52 of the NFPA 70B, 2016:
"The maintenance supervisor should have open lines of communication with design supervision."
Concurrently, the personnel selected for maintenance duties should be skilled in their respective areas. This includes the technical know-how of both electrical and mechanical parts of the equipment as well as having sound knowledge of all electrical safety policies and procedures.
If training is required for areas such as high voltage equipment, then it must be provided well before the assignment of duties.
The first step in determining the frequency of the program is to identify high priority and low priority equipment. This is a very important step, it can eventually save time and money.
Once this classification is complete, then long term maintenance plans can be executed. These can be done;
A general rule of thumb is to have maintenance scheduled every 3 years for critical equipment. Though it is difficult to determine the exact schedule of a shutdown for a facility running 24/7, there are certain instances where guidelines can be followed.
Article 8.2.2 of the NFPA 70B, 2016 provides a guideline for scheduling maintenance for low voltage circuit breakers:
"Low-voltage power circuit breakers should be inspected on an annual basis and tested under simulated overload and fault conditions every 3 to 5 years."
Once the high priority items are completed, maintenance planned for low priority items can commence. Factors affecting the intervals include environmental conditions, loading variations, and the general criticality of the equipment. Engineering analysis should be performed to determine the specific intervals between maintenance activities for equipment operating under harsh environmental conditions.
The biggest hindrance to effective scheduling is the spontaneous occurrence of emergency breakdowns which are uncalled for. Regular inspections can help to eliminate these unplanned failures and interruptions.
Electrical power systems studies are an integral part of an effective equipment maintenance program. They provide valuable information for the reliability assessment of the system. According to the NFPA 70B, they are divided into 5 separate categories:
Short Circuit Analysis is required to provide necessary overcurrent protection devices in the distribution system that will prevent injury to personnel, minimize damage to system components, and limit the extent and duration of service interruption during equipment failures, overload, or short circuit conditions.
If you want to read more about the Short circuit study, click here.
Coordination Studies are used to analyze the short circuit currents and achieve an optimal balance between equipment protection and fault isolation that is consistent with the operating requirements of the electrical network.
AllumiaX also performs the protective device coordination study, as a part of the Arc flash study.
Load flow studies are used to develop and evaluate actual steady-state power system operating conditions in order to evaluate bus voltage profiles, real and reactive power flow, and losses.
Reliability Studies are required for the identification of root causes that can lead to emergency breakdowns and improve the system efficiency in the long term.
Arc Flash Studies are performed over a period of every 5 years to identify the arc flash hazards at each electrical point and quantify their intensity levels.
An effective electrical equipment maintenance plan (EMP) should be in compliance with the latest industrial standards and guidelines which include but are not limited to the following:
Once the priority list has been finalized, the next step involves the surveying of the high priority items for identification of potential causes of concern.
As per Article 5.5.1 of the NFPA 70B, 2016:
"Survey and analysis should cover equipment and systems that have been determined to be essential in accordance with a priority plan."
All kinds of electrical equipment are required to be carefully inspected and decisions to be taken thereby. Physical condition, loading, operation within limits, and the environmental conditions are some of the parameters which need to be analyzed during the survey process.
Each inspection should be conducted so as to meet the critical requirements set during the initial phase. This can be achieved by tightly knitted coordination between all relevant departments involved in the execution of the equipment maintenance plan.
Proper documentation of all survey reports, procedures, and tests should be maintained for future reference.
As stated in Article 184.108.40.206 of the NFPA 70B, 2016:
"Care should be taken to ensure that all relevant information becomes part of the record."
Once the surveying process is completed, the next step would involve the analysis and evaluation of the information collected. The analysis phase would determine the corrective measures required for each specific piece of equipment.
The final step involves the implementation of corrective measures through scheduled maintenance activities and procedures. For each system operating under normal conditions, each discrete component as well as the connections between those components are required to have dedicated sets of procedures.
Every set should have its own forms and reports based on the application of the prescribed maintenance procedures.
Separate procedures should be maintained for emergency areas such as electrical and mechanical interlocks, fire alarms, shutdown safeguards among others. NFPA 70B 2016 classifies the major types of equipment into the following main categories:
Effective and timely implementation of the maintenance procedures marks the culmination of the equipment maintenance plan.
Thank you for reading this blog. If you have any questions or feedback, kindly mention it in the comments section.
About The Author
Abdur Rehman is a professional electrical engineer with more than eight years of experience working with equipment from 208V to 115kV in both the Utility and Industrial & Commercial space. He has a particular focus on Power Systems Protection & Engineering Studies.