Fuji Electric FA Components & Systems Co., Ltd.

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Changes of Medium-voltage devices in the panel

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Recommendation of preventive maintenance


Renewing equipment at the appropriate time prevents serious accidents and their spread

Power receiving and distribution equipment have its life span.

For a safety use of power receiving and distribution equipment, appropriate operating environments recommended by electrical manufacturers, periodic maintenances and inspections, and appropriate equipment replacements are important.


Preventive maintenance is important

 Preventive maintenance is based on the idea that equipment is renewed or repaired before its life expectancy is reached when allowable failure rate values are exceeded. Preventive maintenance reduces failure rates (including power outages and accidents) significantly.
  1. Time based maintenance: planned replacement and repair before the failure rate exceeds its allowable value.
  2. Condition based maintenance: planned replacement and repair when the failure rate exceeds its allowable at periodic diagnosis.
★High-voltage equipment needs appropriate preventive maintenance with consideration to power outages, aftereffects, and other influences.

(a) Early failure period: After a start of operation, there are possibilities of weaknesses that take time to adopt to an external environment and of failures in manufacture.
(b) Random failure period: The failure rate constantly continues without any relation to elapsed time.
(c) Wear-out failure period: The failure rate keeps increasing due to equipment deterioration or wear of components. This is the period witch you have to consider an overhaul or a Upgrade of equipment for maintaining the functionality as a facility.


Recommended Upgrade periods of equipment

The Japan Electrical Manufacturers' Association (JEMA) suggests the following recommended Upgrade periods by type of equipment used for high-voltage facilities based on reports from the Institute of Electrical Engineers of Japan and questionnaires to business operators by the Ministry of Land, Infrastructure, Transport and Tourism.

Product Recommended Upgrade period (after start of use)
High-voltage AC load break switch* Indoor use: 15 years or 200 load current switch operations
Outdoor use: 10 years or 200 load current switch operations
GR switch control equipment: 10 years after start of use
Disconnecting switch Manual operation: 20 years or 1,000 operations
Power operation: 20 years or 10,000 operations
Lightning arrester 15 years
AC circuit breaker 20 years or specified switching times
Instrument transformer 15 years
Protective relay 15 years
High-voltage current-limiting fuse Indoor use: 15 years
Outdoor use: 10 years
High-voltage AC magnetic contactor 15 years or specified switching times
High-voltage phase advancing capacitor,
series reactor, uncontrolled/unused coil
15 years
15 years
High-voltage distribution transformer 20 years
Molded case circuit breaker,
earth leakage circuit breaker
15 years or specified switching times Low-voltage magnetic contactor/switch
Low-voltage magnetic contactor/starter 10 years or specified switching times

1 )This recommended Upgrade period is not a value for functionality or performance guaranteed by manufacturers, but indicates the period in which it is considered generally more advantageous to replace the equipment with new equipment, in view of cost efficiency, given that the equipment is used under normal conditions and with the normal maintenance and inspection.
2 )The period indicated for equipment with an asterisk does not mean the maximum life before which the equipment should be replaced. The indicated period is provided on the assumption that consumables, wear parts, electronic parts, etc. should be replaced appropriately according to the maintenance and inspection results or the parts replacement criteria recommended by the manufacturer. In addition, before using spare parts which have been stored for a long time, perform sufficient inspection and maintenance on them.


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