For Crane Duty contactor shall be selected as per AC-4 rating at 2Lac operations

Requirement

• Motor Type- Squirrel cage motor
• Application- Crane
• Switching Operations per day: 300
• Rated Motor current: 30A
• Desired Contactor Life: 3 Years

Note: If life requirement is not given, a standard benchmark of 2Lac operations can be considered as expected life of contactor.

• Utilization category applicable is AC-4
• No. of operations required - 300(per day ops) X 365 (days in an yr) X 3 years = 328500 ops or approx. 0.33 million ops

AC-4 Electrical life curve for MO contactors

 

Conclusion

From the electrical life curve it is clear that for a requirement of 30A, AC-4 duty, 300ops/ day, expected life 3 years – MO 95 shall be selected