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  1. rocmor

    Are there usually two trip coils on medium voltage power circuit breakers?

    Basically, yes. For both closing and opening operations, there are specified speeds for the main contacts inside the breakers. Large springs, used to supply the mechanical energy required to open and close the contacts, are charged either by a small motor inside the CB or by the energy released...
  2. rocmor

    ANSI Circuit Breaker using on 50Hz system

    As I said, my best guess, based on what you've told me, is that the CB will likely perform properly as far as interruption is concerned. Beyond that, there are other components within a CB (solenoids, charging motors, etc.) that could be adversely affected by the change in frequency. I...
  3. rocmor

    ANSI Circuit Breaker using on 50Hz system

    My comments are based on my past experience in vacuum interrupter (VI) design and application. I feel fairly confident that they will apply equally to SF6 CBs. Both technologies are robust and well suited for the kind of application you seem to be targeting. The issue of going from an ANSI to...
  4. rocmor

    Selection Between Single Breaker System & Double Breaker System

    What are the short-circuit requirements for the proposed double breakers? How are these breakers actually configured: two poles per phase with a total of 6 poles operated by a single mechanism, or two 3-pole CBs operated "simultaneously"? What is the interruption medium (vacuum, SF6...)?
  5. rocmor

    Possible Transient Recovery Voltage Issues

    The "contactors" on the 4160V side - are they indeed contactors or are they circuit breakers used for switching the heavy inductive loads? The reason for asking is that the materials used for the contacts inside the vacuum interrupters are different for (motor) contactor and general circuit...
  6. rocmor

    Rated breaking current vs small inductive breaking current rating

    The overvoltage could be TRV. Overvoltages can also occur during capacitor switching and other duties, and can reach values of 2.5 pu in normal conditions. Depending on the type of breaker you're using (I'm assuming it's an SF6 CB though vacuum CBs have been produced for 145kV application)...
  7. rocmor

    Rated breaking current vs small inductive breaking current rating

    As far as your original question, the ratings you quoted for short-circuit breaking, capacitor switching, cable charging, etc. represent the levels to which the CB was tested and "certified" in an independent high-power test facility, in accordance with IEC/ANSI/IEEE procedures. As bacon4life...

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