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Motor Control Centers Bulletin 2400 Application-Rated Units

Choosing the Correct Contactor

Application Data When selecting Bulletin 2400 application-rated motor control center units, it is important to properly size the contactor for the required application and desired electrical life. The life load curves on pages 8 and 9 are supplied to provide guidance in correctly sizing the contactors. For the enclosed ratings, see individual unit information. For additional contactor specifications, refer to publication 0100C-1.0.1, MCS, The Modular Control System or publication A11_, Allen-Bradley Industrial Controls .

Estimated Electrical Life

Life Load Curves The Bulletin 100 IEC based contactors used in Bulletin 2400 MCC units are designed for superior performance in a wide variety of applications. When selecting IEC based products, the user must give consideration to the specific load, utilization category, and required electrical life of the application. The life load curves shown on pages 8 and 9 are based on Rockwell Automation tests according to the requirements defined in IEC 947. Since contact life in application conditions is dependent on environmental conditions and duty cycle, actual application contact life may vary from that indicated by the curves shown. To find the contactor’s estimated electrical life, follow these guidelines:1.Choose the appropriate graph for the utilization category. (Typical duty for each category is listed below.) 2.Find the operating current, Ie on the horizontal axis, for the contactor’s application.3.Find the number of operations desired on the vertical axis.
4. Find the point where the lines from 2 and 3 intersect. To determine the contactor size, pick the contactor life load curve that is nearest to the point of intersection
. Category Typical Duty AC1Non-inductive or slightly inductive loads (consult your local Rockwell Automation Sales Office for life curves)AC2Starting of slip-ring motors (consult your local Rockwell Automation Sales Office for life curves)AC3Starting of squirrel cage motors and switching off only after the motor is up to speedAC4Starting of squirrel cage motors with inching and plugging duty (assuming locked rotor current 600% of full load current) Publication 2400-CA001B-EN-P—September 20057