Operator safety Motor Control Center solutions review

MCC Drawer operation

This article is related to our collaborative Newsletter, special edition which has been dedicated to a review of new Motor Control Center drawer solutions to improve the safety of operators (closed door operation, internal arc resistant … ).

If you didn’t read this newsletter yet, click here to view it, then come back here to answer the related questions below.

Thank you to contribute to the validation, completion and enrichment of this review, by answering the following questions:
 (add your answers below as a comment to this topic)

  • Do you agree with us that this solution is a real improvement for operator safety?
    Or do you know other solutions which are more relevant/efficient to improve operator safety?
  • Do you see other advantages of such solutions (reduced down-time? reduced insurance cost? …)?
    And what are the drawbacks? Why isn’t it more frequently used today?

    Closed door operation - changing drawer position

  • Are the comparison criteria clear enough? comprehensive?
    Do you know other manufacturers or products?
    In which countries?
  • Do you use these solutions in your country? In which applications?

 Thanks again for your contribution !


  • I believe that this is a very worth while development. We see the issue of protecting the operator against arc flash becoming much more relevant these days with requirements for remote operation and racking of all functional units being requested by customers. We our selves are working on the development of a withdrawable solution for our AMS switch gear range ans this is one of the concepts that we will be including in the design.

    • @ Jerome McEvoy
      Remote operation: In which applications do you have these requirements? When you say for all functional units, do you mean for incomers and all feeders? How often do you get these requirements?

      • We see the requirement for remote operation and racking of incomer and feeder ACBs and MCCBs mainly form Anerican owned companies with plants in Europe. These requirements generally apply to main LV distribution boards where the fault level can be quite high (80 to 100kA). Within the last two years we are finding that customers are writing this into their specifications.

  • I believe this is a good improvement, however, personal protective equipment should not be neglegted when disengaging these panels.Never assume electricity not alive, even if made safe.

    • Very good point Johan. PPE must be used weather the panel is Arc resistant or not.
      If panel is arc resistant PPE requirement may become quite low but it should not be

  • Generally safety of operator depends on:
    1. Eliminating the Risk by design which the subject of discussion.
    2. By procedure i.e. work permit and Risk assessment prior to start the Task ie.propablity and consequences. This depends on the industry and location, i.e. Oil and Gas, indoor or outdoor etc.
    3. operator well trained .
    In oil and Gas all these solution are required and respected, in addition to that isolation and mechanical interlock is required and has to be well engineered.

    • @ Raouf Kahla

      Regarding the elimination of the risk by design, can you give us more details about the requirements in the Oil&Gas application ?

      And what do you mean when you say “isolation and mechanical interlock is required and has to be well engineered” ?

  • @ Laribee Adams

    When you say that the safety is high on these panels, which safety functions does it provide:
    * internal arc resistant?
    * closed door operation?
    * IP is maintained when the drawer is removed?

    What do you expect in term of safety in your cement applications?

  • @ Jerome McEvoy

    Interesting to see this trend to require remote racking for main LV switchboards!

    And you mean that remote racking is required not only for ACBs, but also for MCCBs? Down to which minimum rating, I wonder? And for what type of applications?

    What about the MCC switchboards? Any similar evolutions you see in specifications?

  • Interesting about the topic,

    3 point , technical aspect and ecnomic and safety awarenes

    my share information are ;

    all swithcboard must be fully type tested !

    1, technical aspec yes absolutely agree it is big improvement to reduce such as ;shutdown time , safety , and predictive maintenace and trouble shuting ( Smart mcc fully witdrwable )
    2, Eceonmic aspec some brand yes really expensive since orginaly assemblied in Europe , but some brand which has been assembleid in local through franchise system more cheap or economist with good quality
    3, some development country no body aware Safety is high on these panels and they are well secured , and last but not least related inurence company coverage , some of them dont care international standart required for LV switchgear

  • Yes, this will be a big improvement in electrical safety. Probably cost is the big reason why it isn’t done more. It’s always difficult to convince management people to spend more than they have to for any installation.

    One thing we did as a temporary measure with MCC’s and switchgear was install custom-made time delay close/trip switches, to allow personnel time to simply get out of the way while the breaker closes or trips. But the need to withdraw the breaker still presents a hazard. That’s where this new withdrawal solution can make it safer.

    • Thank you Steve, you have expounded an interesting safety solution for maintenance operators.

      Could you tell us more about this system?

      Is it only on incomers? (It seems complicated on feeders in low voltage)

      • Thank you for your interest, Laurent. Our Plant is a Class 4 Wastewater/Sewage Treatment Plant, with two 27.6 kV incoming lines, and 4160 volt distribution across the plant, to 600 volt MCC’s, etc. After a Plant-wide electrical assessment was done two years ago, and an Arc Flash Study completed, we found that some of our arc flash levels were too high for any PPE to protect. So, we talked to Electroswitch, who were beginning to manufacture Close/Trip switches with built-in electronic time delay relays. They feature the usual pistol grip for immediate closing or tripping, with the addition of time-delayed closing and tripping by means of color-coded push buttons, with LED’s that flash as the timer is timing. During the last few seconds of timing, the LED will flash at twice the frequency, as an added warning that closing or tripping is about to occur. These switches also have the feature of allowing you to ‘cancel’ the timing sequence by pressing the other push button. For example, if you are timing out a Closing operation, you can cancel it during the timing by pressing the Trip button. We have a system of Main-Tie-Main breakers on our substation breakers and on our 600 volt switchgear mains, and these are the breakers that we are installing the time-delay switches on, wherever there were existing Close/Trip switches. (So we did not put them on MCC’s, for example). What this does for us is 1) It gives us immediate protection for personnel doing the switching, and 2) It buys us time to have the proper engineering done to mitigate the arc flash hazard levels.

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