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Lock-out relays

Discussion in 'System Modeling and Calculations' started by tricard, Dec 4, 2009.

  1. tricard New Member

    Hi everyone,

    I am doing an arc flash study for a generating station that protects the main generator buses through lockout relays (i.e. 50/51/87 etc. element actuates the 86 element which in turn initiates the circuit breaker trip coil). It turns out there is a wide variance of activation times on these lockout relays (from reading on-line specs) and it is not particularly easy to get this data from the client. How does everyone incorporate the 86 element time into their model? I have heard times ranging from 130ms all the way down to 8ms... makes a pretty big difference in HRC.

    Thanks in advance for the input.

    Tim Ricard
    tricard, Dec 4, 2009
    #1

  2. stevenal Well-Known Member

    Electroswitch says .5 cycle.
    stevenal, Dec 18, 2009
    #2

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