CM-MPN Automatic Phase Sequence Correction, Saves $$

2010-03-08 - The CM-MPN family of 3-phase voltage monitors offer a new cost effective, feature rich, solution for protection of rotation sensitive three phase equipment. Container shipping, rail shipping and 3 phase moveable equipment may be reverse phase connected at any time. The CM-MPN senses this dangerous phase reversal fault and signals a reversing contactor to correct the phase sequence before the equipment starts. The CM-MPN provides safer and more reliable mobile equipment operation for 380 to 690 V systems. See the complete application description . . . read more

The ABB CM-MPN monitoring relay provides a new LEAN engineering solution to the problem of incorrect 3 phase voltage connection of mobile equipment. External relays, time delays and associated connections are now eliminated. All you need to provide full 3 phase voltage protection is a reversing contactor and the CM-MPN voltage monitor. Don't risk mobile equipment damage due to reverse connection of power, specify the CM-MPN and A Line reversing contactors; available from ABB stocking distributors throughout USA and Canada. Request a demonstration or quotation today.

This new design utilizes true RMS measuring circuitry that results in extremely accurate operation.

CM-MPN protects against:

  • Phase reversal
  • Phase loss
  • Voltage unbalance
  • Over voltage
  • Under voltage
  • Short cycling

The CM-MPN with a reversing contactor provides automatic phase sequence correction:
The CM-MPN monitors the 3 phase voltages for proper voltage level on all three phases during a short start up delay. Relay R2 energizes first if the phase sequence is correct. When all voltages are acceptable internal relay R1 energizes allowing the motor or equipment to start. These contacts are connected to a reversing contactor to automatically correct the phase sequence (if needed) before permitting the equipment to energize. (see application images).
Application Description: To use this application the phase sequence monitoring function must be selected, the operating mode must be 2x1 c/o (SPDT) and the control circuitry must be wired as shown.
Control Circuit Diagram showing relay and coil connections

At the end of the 200 ms "ts2" startup delay, if the phase voltages are present and the phase sequence is acceptable, R2 (in circuit diagram K1) energizes transferring contacts 25-26, 25-28. This establishes the correct state of the reversing contactor before power is applied. (50 ms later) At the at the end of the 250 ms "ts1" startup delay, R1 (in circuit diagram K1) energizes transferring contacts 15-16, 15-18. If the phase sequence is correct, closing the R1 15-18 contacts applies power to the K2 coil of the reversing contactor. The motor is energized and rotates in the forward direction. If the phases are reversed, R2 does not energize after the Ts2 time delay. When R1 energizes the K3 coil of the reversing contactor is energized effectively reversing (correcting) the phase sequence problem. The motor starts and runs in the forward direction. If an over, under or unbalance fault occurs the R1 15-18 contacts open, however the R2 contacts do not transfer as they only respond to phase sequence, in this application.
Power circuit diagram showing motor and reversing contactor connections
Contact ABB Low Voltage Products technical support for complete details.

CM-MPN features include:
  • Wide operating voltage means one unit protects any size 480 to 600 VAC motor (reversing contactors vary)
  • Independently adjustable under and over voltage thresholds
  • Selectable phase sequence monitoring
  • Optional interrupted neutral monitoring
  • Adjustable phase unbalance settings
  • DIN 3 rail mounting
  • IP 20 Touch safe screw terminal connections

Additional product information is included in the new 2009 Electronic Products and Relays catalog. See the related links on this page.

ABB is a leader in power and automation technologies that enable utility and industry customers to improve their performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 120,000 people.

For more information, see the Related Links on this Page

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    CM-MPN 3 Phase Sequence Monitor
    CM-MPN 3 Phase Sequence Monitor

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