24-09-2014, 03:44 PM
Electrical equipment failures account for millions of dollars in damage and lost business every year. As this country�s electrical infrastructure continues to age, this problem is only going to worsen unless active steps are taken to counter the trend. Ironically, more than two-thirds of electrical system failures can be prevented by a routine preventive maintenance program. Studies show that the failure rate of electrical equipment is three times higher for components that are not part of a scheduled preventive maintenance program as compared with those that are. In addition, a planned EPM program allows the equipment owner to schedule the system outage at a time of their choosing rather than having to correct major problems resulting from an always untimely failure. The purpose of this standard is to provide the insured with recommended practices and frequencies that would form the core of a regularly scheduled electrical preventive maintenance program. All work associated with electric power systems and equipment should be performed in accordance with accepted indust
PROJECT REPORT
3.1 NAME OF PROJECT ELECTRICAL MAINTENANCE
Electrical equipment failures account for millions of dollars in damage and lost business every year. As this country’s
electrical infrastructure continues to age, this problem is only going to worsen unless active steps are taken to counter the
trend. Ironically, more than two-thirds of electrical system failures can be prevented by a routine preventive maintenance
program. Studies show that the failure rate of electrical equipment is three times higher for components that are not part of a scheduled preventive maintenance program as compared with those that are. In addition, a planned EPM program allows the equipment owner to schedule the system outage at a time of their choosing rather than having to correct major problems
resulting from an always untimely failure.
The purpose of this standard is to provide the insured with recommended practices and frequencies that would form the core of
a regularly scheduled electrical preventive maintenance program. All work associated with electric power systems and
equipment should be performed in accordance with accepted industry safety standards and work practices.
Frequency of EPM
In general, Hartford Steam Boiler recommends a frequency of once every three years for conducting regular preventive
maintenance on electrical equipment. Where applicable, this standard will note components that require a more frequent EPM
program to help ensure reliability and operation.
It is recognized that individual locations may require more frequent maintenance due to the physical environment or
operational nature of the equipment. For example, harsh environments where excessive moisture or dust may be present should
have a more frequent EPM program. Similarly, equipment that is used intermittently or equipment critical to a key process
should be considered for a more frequent program. Sound engineering judgment should be used in determining if more
frequent maintenance is appropriate.
3.0 Recommended Maintenance Practices
The following sections are segmented by equipment type. For each component, a recommended minimum practice for
preventive maintenance is provided. Where applicable, additional suggested practices are presented for a more thorough
3.1.1 SWITCHGEAR
Ensure that all enclosure panels, doors, and structures are well-maintained in accordance with the manufacturer’s
specifications. During deenergized maintenance, enclosures are to be vacuum cleaned of all loose dirt and debris — use of
compressed air is not recommended since this may cause foreign particles to become embedded in the insulation or damage
insulators. Any buildup of dirt or other contaminates that will not come off with vacuuming should be cleaned with lint free
rags using cleaning solvents recommended by the manufacturer.
Standard for an Electrical Preventive Maintenance Program
Electrical equipment rooms or vaults should be kept cleaned of dirt and/or dust accumulations on a regular basis. Doors and
windows should be maintained in proper working order and kept closed during routine operation. Access doors should be
clearly marked to alert personnel that live electrical equipment is in use. Where ventilation and/or air conditioning is used, all
fan motors should be cleaned and examined for signs of wear and deterioration. Fan blades should be cleaned of dirt and dust
and bearings should be properly lubricated. Vent openings should be cleaned of all dust and dirt accumulations. Filters should
be cleaned and/or changed as recommended by the manufacturer, or more often if conditions warrant. Electrical equipment
rooms should never be used as storage areas.
Electrical equipment rooms or vaults should be examined for evidence of water seepage. The tops of electrical equipment
enclosures should be examined for evidence of water since this is a common entryway that often goes undetected until a
failure
occurs. The source of the water should be immediately identified and corrective measures taken to permanently correct the
condition.
3.1.2 INSULATORS, SUPPORTS, AND CONNECTORS
Inspect insulators and conductor supports for signs of cracking, broken pieces, and other physical damage or deterioration.
Clean all loose dirt with lint free rags. For contaminates that will not remove easily, solvents approved by the manufacturer
may be used. Examine for evidence of moisture that may lead to tracking or flashover while in operation. Examine
surrounding areas for signs of tracking, arcing, or overheating. Repair or replace damaged insulators and supports as
necessary.
Examine all bolts and connecting devices for signs of deterioration, corrosion, or overheating. Ensure that bolts and connecting
devices are tight, according to manufacturer’s specifications. Be careful not to overtorque bolts and connecting devices since
insulators are easy to damage and difficult to replace. Where copper and aluminum conductors and/or connectors are used
together, examine connections for signs of galvanic action. Ensure that the connectors are properly used and installed in
accordance with manufacturer’s specifications. Apply an antioxidant compound to all aluminum-to copper connections.
3.1.3CONDUCTORS
Examine insulation for signs of deterioration, cracking, flaking, or overheating. Examine all connections for signs of
overheating, cracked or broken connectors, and signs of tracking or arcing. Ensure that conductors are clean and dry. Examine
and clean all connections, and torque to manufacturer’s recommendations.
3.2AIR CIRCUIT BREAKERS
Insulation
Remove and clean interphase barriers. Clean all insulating materials with vacuum and/or clean lint free rags. If it is necessary
to use cleaning solvents, use only solvents recommended by the manufacturer. Inspect for signs of corona, tracking, arcing, or
thermal or physical damage. Ensure that insulation is left clean and dry.
3.2.2CONTACTS
Ensure that all contacts are clean, smooth, and in proper alignment. Ensure that spring pressures are maintained according to
manufacturer’s specifications. On silver contacts, discoloration is not usually harmful unless caused by insulating deposits.
Clean silver contacts with alcohol or silver cleaner using non-abrasive cloths.
Manually close breaker to check for proper wipe, contact pressure, contact alignment, and to ensure that all contacts make at
approximately the same time. If possible, a contact resistance test should be performed to determine the quality of the contacts.
Older breakers equipped with carbon contactors generally require very little maintenance. Examine for proper pressure,
deterioration, or excessive dressing which may interfere with their proper operation.
Draw-out contacts on the circuit breaker and the stationary contacts in the cubicle should be cleaned and inspected for
overheating, alignment, and broken or weak springs. Coat contact surfaces with contact lubricant to ease mating (see
manufacturer’s recommendations).
#420 (rev 02/10) Standard for an Electrical Preventive Maintenance Program
3.2.3ARC INTERRUPTERS
Clean all ceramic materials of loose dirt and examine for signs of moisture, make sure the assemblies are clean and dry.
Examine for cracked or broken pieces. Dirt and arcing deposits may be removed by light sanding — do not use emery cloth or
wire brushes which may leave conductive residue behind. Repair or replace as necessary.
Examine arc chutes for dirt and/or dust accumulations and clean as necessary. Dielectric testing of arc shields may be
recommended by the manufacturer. Check air puffer for proper operation.
3.2.4OPERATING MECHANISM
Inspect for loose, broken, worn, or missing parts (consult manufacturer’s schematics for required parts). Examine for excessive
wear of moving parts. Observe that operating mechanisms function properly without binding, hanging, or without delayed
action. Ensure any lubrication is done according to the manufacturer’s specifications. Ensure mechanisms are clean, properly
lubricated, and all bolts and screws are properly secured. Repair or replace as necessary.
3.2.5AUXILIARY DEVICES
Inspect operating devices for proper operation and general condition. Ensure all indicating devices are fully functional and
properly set. Protective relays and circuit breaker trip devices should be inspected and tested according to manufacturers’
specifications and applicable industry standards such as those issued by the Institute of Electrical and Electronics Engineers
(IEEE) and the National Fire Protection Association (NFPA).
3.3VACUUM CIRCUIT BREAKERS
All maintenance is similar to that performed on air circuit breakers. As always, it is recommended that the manufacturer be
consulted for specific maintenance and testing procedures.
The integrity of the vacuum chamber is often tested by applying a test voltage across the open contacts of the breaker.
However, this can be a destructive test and is therefore not recommended by Hartford Steam Boiler.
Caution: This procedure can produce X ray emissions, so personnel should maintain a safe distance from the breaker if this
test is performed. It is important to closely follow manufacturer’s recommended procedures if conducting this test in order to
ensure that proper results are obtained. The breaker vapor shield can accumulate an electrostatic charge during this test.
Ensure that it is discharged immediately following the test.
3.4AIR DISCONNECT SWITCHES
Inspect and clean insulators and conductors as with circuit breakers. Tighten connections in accordance with manufacturer’s
specifications. Do not overtighten as this may result in damage to connectors.
If cleaning solvents are used, ensure that they are as recommended by the manufacturer. Where abnormal environmental
conditions exist, more frequent inspection and cleaning may be required.
Check the operation of the arc blades, if applicable, and ensure proper wipe of the main contacts. Interphase linkages and
operating rods should be inspected to make sure that the linkage has not been bent or distorted and that all fastenings are
secure. The position of the toggle latch to the switch operating linkage should be observed on all closed switches to verify the
switch is mechanically locked in a closed position. Operate switch manually several times to ensure proper operation, and then
by motor if power-operated. Ensure that all moving parts are properly secured and lubricated as specified by the manufacturer.
Contact resistance testing of each phase contact should be performed. The results should be recorded and analyzed to ensure
proper contact is being made. If the contact resistance of the switch exceeds recommended minimums, repair or replace the
switch immediately.
3.5 STANDARD FOR AN ELECTRICAL PREVENTIVE MAINTENANCE PROGRAM
3.5.1OIL CIRCUIT BREAKERSEXTERNAL
Inspect the enclosure for signs of oil leakage. Clean external bushings assemblies and examine for signs of deterioration,
tracking, and loose or broken parts. Observe oil gauge to ensure device is operating properly and measuring the oil level
accurately.
3.5.2INSULATING OIL TEST
Conduct a dielectric screen test of the insulating fluid. Based on the results of this test, filter or replace oil as required. Heavy
carbon content can indicate potential contact wear and should be investigated further.
3.5.3INTERNAL
Since the contacts for oil circuit breakers are not readily accessible for inspection, the contact resistance should be tested as a
minimum.
More extensive maintenance on the contacts might be require draining the oil and dropping the tank, and is therefore
performed less frequently. Follow manufacturer’s recommended schedule for examination of internal components such as
contact inspections. Open breaker and examine contacts for wear and/or excessive deterioration. Examine linkages for loose,
broken, or missing parts; repair or replace as necessary.
3.5.4AUXILIARY DEVICES
Operating mechanisms should be maintained as with air circuit breakers. Where applicable, examine oil level indicators, sight
glasses, oil lines, gaskets, and tank lifters for proper conditions. Repair or replace as necessary and in accordance with
manufacturer’s recommendations.
Examine arc-quenching assemblies for carbon deposits or other contaminates. Follow manufacturer’s recommendations for
cleaning.
3.6MOLDED-CASE CIRCUIT BREAKERS
Molded-case circuit breakers should be kept clean for proper ventilation of the breakers. These types of breakers are usually
tripped by a thermal element that senses an increase in temperature due to excessive