Product Life Of Relay Contacts - Mitsubishi FX2N SERIES Hardware Manual

FX2N Series Programmable Controllers
6.1.1

Product life of relay contacts

Product life of relay contacts
ENG
The product life of relay contacts considerably varies 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 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 6.2 were gathered from a 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.
Table 6.2:
20VA
35VA
80VA
The product life of relay contacts becomes considerably shorter than the above conditions when the rush overcurrent is
shut down.
*
For countermeasures while using inductive loads, refer to "Output circuit configuration" below in this section.
Some types of inductive loads generate the rush current 5 to 15 times the stationary current at activation.
Make sure that the rush current does not exceed the current corresponding to the maximum specified resistance
load.
2) Lamp load
Lamp loads generally generate rush current 10 to 15 times the stationary current.
Make sure that the rush current does not exceed the current corresponding to the maximum specified resistance load.
3) Capacitive load
Capacitive loads can generate rush current 20 to 40 times the stationary current.
Make sure that the rush current does not exceed the current corresponding to the maximum specified resistance load.
Capacitive loads such as capacitors may be present in electronic circuit loads including inverters.
*
For the maximum specified resistance load, refer to Section 6.1.
Load capacity
0.2A/100V AC
0.1A/200V AC
0.35A/100V AC
0.15A/240V AC
0.8A/100V AC
0.33A/240V AC
Life contact (cycles)
3,000,000
1,000,000
200,000
Outputs 6
6.1.1
1
2
3
4
5
6
7
A
B
C
6-3