overload and overcurrent relays

Discussion in 'General Electronics Chat' started by morgenstern, Feb 16, 2014.

  1. morgenstern

    Thread Starter New Member

    Feb 28, 2013
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    [​IMG]
    Can we use these instead of fuse and bimetal?
    if not why not?
     
  2. inwo

    Well-Known Member

    Nov 7, 2013
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    Similar trip to bi-metal or overload protectors with heater elements, but slower than fuses.

    It depends on the application.
     
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  3. morgenstern

    Thread Starter New Member

    Feb 28, 2013
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    A fuse will burn at last and will disconnect the circuit; Can this device do something like that?
    And bi-metal trip the both of control circuit and power circuit but this device seems just trip the power circuit?
    am i true?
     
  4. Wendy

    Moderator

    Mar 24, 2008
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    I have moved this thread to a more appropriate forum. Good luck.
     
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  5. inwo

    Well-Known Member

    Nov 7, 2013
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    True.

    I don't see control circuit connections.:confused:

    It looks like a manual starter.
    Do you have specs?

    There are similar devices. Electronic overload assemblies that open the control circuit to the motor starter.
    Here is example from inventory that connects to bottom of contactor and opens a (pilot) control circuit.
     
    Last edited: Feb 16, 2014
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  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    That is commonly termed a NFB or Non Fused Breaker, in a control enclosure you would typically see main fuses which would branch out to these devices to control such equipment as motors and other 3ph controlled items.
    Often used where the device itself did not have its own contactor with O/L attached.
    The main enclosure disconnect itself is often a NFB
    Max.
     
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  7. inwo

    Well-Known Member

    Nov 7, 2013
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    The non fused breakers I've seen look like panel mount breakers but are just a switch.

    Lots of names.

    I believe that a closer description might be a manual starter or motor protection breaker.

    Its the short circuit protection, overload, and starter in one package.

    Similar:

    Manual motor starters - M
    • Overload and short-circuit protection.
    • Overload range adjustable from 0,1 to 32A.
    • Wide range of accessories.
    • Suitable for small size motors in machine-tools,
    conveyor systems, etc.
    • Modular size 45 mm. DIN rail mounting (EN
    50022-35).
    • Isolating and main switch function (IEC 204-1).

    http://www.directindustry.com/prod/...protection-circuit-breakers-20885-491547.html
     
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  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Could be closer description.
    From the manuf site:
    MS32 Motor Starter
    MS32 Series motor protection switch are suitable for using in the circuits up to rated voltage 690V AC 50/60Hz. The unit protects the installation against overloads, short circuits and reacts to phase failure in strict compliance with IEC947-4-1

    Max.
     
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