(1) Thermal degradation. Insulation material aging, rubber aging, contact resistance increase, etc. due to an increase in heating temperature.
(2) Electrical degradation. The electric field concentration of the insulating material causes a decrease in insulation performance and the like.
(3) Mechanical deterioration. Damage, deformation, cracking and wear of parts caused by mechanical stress.
(4) Environmental degradation. Detergency, corrosion, moisture absorption and deterioration of lubricating oil caused by environmental factors.
Usually, single factor degradation is less, and most of the factors are degraded. The failure modes caused by other factors of heat synthesis are as follows:
(1) The temperature rises - the insulation material decreases in the moon's edge resistance - dendritic discharge - flashover, short circuit.
(2) The effects of contamination, dust, mechanical stress and corrosive gases lead to a decrease in the insulation capacity inside and on the surface of the insulating parts - the temperature rises - the effect is intensified - the internal breakdown of the parts.
(3) Increased contact resistance of the contact due to environmental or assembly, poor operation - temperature rise - greater contact resistance - short arc - flashover, short circuit
(4) Same as (3), causing the welding of the control device or the switch electrical contact - control failure, switch rejection.
(5) Temperature rise and mechanical and environmental factors - the mechanical strength of the parts is reduced - equipment damage.
(6) Temperature rise - control wire insulation damage - breakdown, control failure.
(7) Internal equipment temperature rise - equipment damage - stop working.
Due to heat, etc., the recommended number of years of use of various equipment in high-voltage switchgear in Japan at normal ambient temperatures is as follows:
(1) High voltage circuit breaker: within 20 years, or the specified number of uses
(2) High-voltage load switch: indoor use, 15 years or open and close load current 200 times; outdoor type, 10 years or open and close load current 200 times.
(3) High-voltage isolating switch: manual type, 20 years or a total of 1000 times; electric type, 20 years or a total of 1000 times.
(4) Arrester: 15 years.
(5) Transformer: 15 years.
(6) Protection relay: 15 years
(7) High-voltage current limiting fuse: indoor 15 years; outdoor 10 years.
(8) Electromagnetic contactor: 15 years or the number of times the joint is specified.
(9) Capacitor: 15 years
(10) Series reactor and discharge coil: 15 years.
(11) High voltage decay transformer: 20 years