Maintenance; Periodic Inspection; Product Life Of Relay Contacts - Mitsubishi FX3UC SERIES User Manual

FX Series Programmable Controllers
3UC
User's Manual - Hardware Edition
12.4

Maintenance

12.4.1 Periodic inspection

Consumable components resulting in a shorter product life are not built in this PLC. However, the following
components have a limited life.
Part
Model FX -32BL battery
3U
Standard life of FX
[Free guarantee period: 1 year after delivery or up to 18 months after manufacture]
• Check that the temperature in the panel is not abnormally increased by other heat generating bodies or
direct sunlight.
• Check that dust or conductive dust has not entered the panel.
• Check for loosening of wiring and other abnormalities.

12.4.2 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.
1) Input/output extension blocks
The standard life of contacts used for Inductive loads, such as contactors and solenoid valves, is 500,000
operations at 20 VA.
The following table shows the approximate life of a relay based on the results of an operation life test.
Test condition: 1 sec. ON/1 sec. OFF
Load capacity
20VA
35VA
80VA
Standard life: 5 years (at ambient temperature of 25°C (77°F))
[Guarantee for 1 year]
-32BL: 5 years (at ambient temperature of 25°C (77°F))
3U
→ For frequency of replacement, refer to Subsection 11.5.4.
Contact life
0.2A/100V AC
3,000,000 times
0.1A/200V AC
0.35A/100V AC
1,000,000 times
0.17A/200V AC
0.8A/100V AC
200,000 times
0.4A/200V AC
12 Test Operation, Adjustment, Maintenance and Troubleshooting
Life
→ For the applicable models, refer to Subsection 1.4.2.
12.4 Maintenance
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