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INTRODUCTION

Electrical equipment failures account for millions of rand in damage and loss business every year. As this countries electrical infrastructure continues to age, this problem is only going to worsen unless active steps are taken to counter the trend.

In addition, a planned EPM programs 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 preventative maintenance program. All work associated with electrical power systems and equipment should be performed in accordanco with the accepted industry safety standards and work practices.

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10 Reasons to perform electrical preventative maintenance

How Often Should Electrical PM be done?

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 dot may be present should have a more frequent EPM program. Sitnilarly, equipment that is used intermittently or equipment critical to a key process should be considered for a more frequent program. Sound engineering judgement should be used in determining if more frequent maintenance is appropriate.

Electrical PM Items

RECOMMENDED MAINTENANCE PRACTICES

3.1 Switchgear

3.1.1 Enclosure

Ensure that all enclosure panels, doors, and structures are well maintained in accordance with the manufacturer’s specifications. During de-energized 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 build-up of dirt or other contaminates that will not come off with vacuuming should be cleaned with lint free rags using cleaning solvent recommended by the manufacturer.

All vents and fan grills are to be cleaned of all dust and/ or dirt accumulations. Ensure that the ventilation openings are not obstructed. Where seals and/ or gaskets are installed, these should be examined and repaired or replaced as necessary. All doors and access panels should be properly secured during operation. Where heater elements are installed, these should be cleaned, examined for damage and/ or deterioration, and tested. Repair or replace heater elements as necessary.

In environments where there is an extreme exposure to adverse condition, the frequency of the maintenance for enclosures should be increased as conditions warrant.

Electrical equipment rooms or vaults should be kept cleaned of dirt/ or dust accumulation on a regular basis. Doors and windows should be maintained in a proper working order and kept closed during routine operations. 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 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 accumulation. 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 conditions.

3.1.2 Insulation, Supports, and Connectors

Inspect insulators and conductor support for sighs 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 necessary.

Examine all bolts and connecting devices for signs of deterioration, corrosion, or overheating. Ensure that bolts and connecting devices are tight, according to manufactures specifications. Be careful not to be over torque bolts and connecting devices since insulators are easy to damage and difficult to replace. Where copper and aluminium conductors and/ or connectors are used together examine connections for signs of galvanic actions. Ensure that the connectors are properly used and installed in accordance with manufactures specifications. Apply an antioxidant compound to all aluminium to copper connections.

3.1.3 Conductors

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 recommendation.

3.2 Air CCircuit Breakers

3.2.1 Insulation

Remove and clean inter-phase 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, thermal or physical damage

3.2.2 Contacts

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, discolouration is not usually harmful unless caused by insulating deposits. Clean silver contacts with alcohol or silver cleaning 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 the 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 c breaker and the stationary contacts in the cubicle should be cleaned and inspected for overheating, alignment, and broken or week springs. Coat contact surfaces with contact lubricant to ease mating (see manufacturer’s recommendations).

3.2.3 Operating 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.

3.2.4 Auxillary Devices

Inspect operating devices for proper operation and general condition. Ensure that all indication devices are functional and properly set. Protective relays and circuit breakers trip devices should be inspected and tested according to manufacturer’s specifications and applicable industry standards such as those issued by the Institute of Electrical and Electronics Engineering (IEEE).

3.2.5 Molded-Case Circuit Breaker

Molded-case circuit breakers are kept clean for proper ventilation of the breakers. These types of breakers are usually tripped by a thermal element that senses an increase of temperature due to excessive current draw. However, if dirt accumulates on the surrounding of the breaker, the heat build-up may not be permitted to dissipate properly and result in nuisance trpping.

Clean the breaker housing and inspect for cracks or signs of overheating. Tighten all connections. Exercise the breaker several times to ensure the mechanism has freedom of movement and to allow contact wipping.

In addition larger duty circuit (225 amps or above) should be electrically trip tested to ensure proper operation of the trip elements and trip linkages.

All molded-case circuit breaker panels should be cleaned of all dirt, dust, and debris using a vacuum.

3.2.6 Transformers

Transformers data (such as voltage, current and temperature readings) should be recorded on a regular basis in order to determine operating conditions of the transformer. Peak, or redline, indications should be recorded and reset. Reading taken on a weekly basis can provide important information about the loading of the transformer that is needed before additional loads can be added to the transformer.

3.2.7 Liquid-Filled Transformer

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