Output Wiring; Relay Output - Mitsubishi Electric MELSEC iQ-F Series User Manual

13.6

Output Wiring

Relay output

Product life of relay output contacts
The product life of relay output contacts varies considerably depending on the load type used.
Note that loads generating reverse electromotive force or rush current may cause poor contact or welding of contacts which
may lead to considerable reduction of the contact product life.
■Inductive load
Inductive loads generate large reverse electromotive force between contacts at shutdown, which may cause arc discharge. At
a fixed current consumption, as the power factor (phase between current and voltage) gets smaller, the arc energy gets larger.
The following table lists the standard life of contacts used for inductive loads, such as contactors and solenoid valves.
Module
CPU module, output module, I/O modules,
powered input/output module
Terminal block
The following table lists the approximate life of a relay based on the results of an operation life test.
• Test condition: 1sec ON/1sec OFF
Module
CPU module, output module, I/O
modules, powered input/output module
Terminal block
The product life of relay contacts becomes considerably shorter than the above conditions when the rush overcurrent is shut
down.
Please refer to the following measures regarding the inductive load.
Page 193 Contact protection circuit for inductive loads
Some types of inductive loads generate rush current 5 to 15 times the stationary current at activation. Note that the rush
current does not exceed the current corresponding to the maximum specified resistance load.
■Lamp load
Lamp loads generally generate rush current 10 to 15 times the stationary current. Note that the rush current does not exceed
the current corresponding to the maximum specified resistance load.
■Capacitive load
Capacitive loads can generate rush current 20 to 40 times the stationary current. Note 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.
Inductive load
20VA
35VA
Load capacity
20VA
35VA
80VA
35VA
80VA
120VA
Standard life
500000 times
0.2A/100VAC
0.1A/200VAC
0.35A/100VAC
0.17A/200VAC
0.8A/100VAC
0.4A/200VAC
0.35A/100VAC
0.17A/200VAC
0.8A/100VAC
0.4A/200VAC
1.2A/100VAC
0.6A/200VAC
Contact life
3000000 times
1000000 times
200000 times
3000000 times
1000000 times
200000 times
13 WIRING
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13.6 Output Wiring
13