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Thread: Standards for TIE breakers

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    Standards for TIE breakers

    Hi all,

    I have been searching, and searching for the standards related to TIE breaker safety.
    Specifically, what is the safe voltage across a tie breaker in which it can be closed (AC & DC)?

    In the Navy, we used a general guideline of <5V, but i can't find a standard (OSHA, NEC, NFPA) which states what the requirement is.

    Please help.

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    Of course ideally it would be 0V, but often it can be closed when the phase difference is less than 10 deg. I don't have that voltage difference handy though ....
    Ron

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    Quote Originally Posted by ron View Post
    Of course ideally it would be 0V, but often it can be closed when the phase difference is less than 10 deg. I don't have that voltage difference handy though ....
    I understand "ideally" and preferred, but i was looking for an official published standard. Or is this more in the realm of "safe practice guidelines" vs actual procedural requirements?
    I'm certain that a standard must exist (at least for DC) as you don't want to close a battery breaker when rectifier voltage is nominal (e.g. -54V), and battery is severely discharged (e.g. 37V).
    That could be very bad, especially on large systems rated for tens of thousands of amps.

    Systems like that generally have engineered safeguards in place to prevent just that. They typically require adjusting rectifier voltage before closing the breaker to match across the breaker.
    But again, by what standard (rule / regulation) is this governed? Is it just company specific to reduce the hazards?

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    Quote Originally Posted by Eldaye View Post
    I understand "ideally" and preferred, but i was looking for an official published standard. Or is this more in the realm of "safe practice guidelines" vs actual procedural requirements?
    I'm certain that a standard must exist (at least for DC) as you don't want to close a battery breaker when rectifier voltage is nominal (e.g. -54V), and battery is severely discharged (e.g. 37V).
    That could be very bad, especially on large systems rated for tens of thousands of amps.

    Systems like that generally have engineered safeguards in place to prevent just that. They typically require adjusting rectifier voltage before closing the breaker to match across the breaker.
    But again, by what standard (rule / regulation) is this governed? Is it just company specific to reduce the hazards?
    I am not aware of a standard regarding this issue.
    Ron

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    Quote Originally Posted by Eldaye View Post
    I understand "ideally" and preferred, but i was looking for an official published standard. Or is this more in the realm of "safe practice guidelines" vs actual procedural requirements?
    I'm certain that a standard must exist (at least for DC) as you don't want to close a battery breaker when rectifier voltage is nominal (e.g. -54V), and battery is severely discharged (e.g. 37V).
    That could be very bad, especially on large systems rated for tens of thousands of amps.

    Systems like that generally have engineered safeguards in place to prevent just that. They typically require adjusting rectifier voltage before closing the breaker to match across the breaker.
    But again, by what standard (rule / regulation) is this governed? Is it just company specific to reduce the hazards?
    Try these, depends on the gear
    For low-voltage PSG:
    •UL 891-2005: Switchboards for dead-front switchboards
    •UL 1558-2016: Standard for Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear and ANSI/IEEE C37.20.1 for metal-enclosed low-voltage power circuit breaker switchgear.

    For medium-voltage PSG:
    •ANSI/IEEE C37.20.2-1999: IEEE Standard for Metal-Clad Switchgear for metal-clad and station-type cubicle switchgear.
    •The equivalent Canadian standard for all the above is CSA C22.2 No. 31-2014: Switchgear assemblies.

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