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FX1N Series Programmable Controllers Outputs 6.
6-3
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6.2.1 Product life of relay contacts
The product life of relay contacts varies considerably depending on the load type used. Take
care that loads generating reverse electromotive force or rush current may cause poor contact
or deposition of contacts which may lead to considerable reduction of the contact product life.
1) Inductive load
Inductive loads generate large reverse electromotive force between contacts at shutdown
which may cause arcing. At a fixed current consumption, as the power factor (phase
between
current and voltage) gets smaller, the arc energy gets larger.
The test results in table 6.1 were gathered from a 1 sec ON/OFF test cycle.
Please note that the over current induced by in-rush greatly reduces the relay contacts
life.
The rated life for an inductive AC load such as a contactor or solenoid valve is 500,000
operations at 20VA.