Instantaneous Trip Tolerances Clarification

Can some one help me undertanding this question and how to solve it:

  • 4. An instantaneous trip test was performed on a set of circuit breakers with adjustable thermal-magnetic trip units during a maintenance outage. The time-current curve specifies an expected trip current of 4000A, which of the following results is unacceptable per NETA standards?
    Your Answer: A-4240, B-5392, C-5224
    Correct Answer: A-3264, B-2775, C-2953
    Help: NETA MTS-2019 Table 100.8
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Per NETA MTS Table 100.8 for an Adjustable trip Therm-Mag unit, the band for allowable Instantaneous trip is +40% and -30%.
So the Max=4000A + (40000.4) = 4000A +1600A = 5600A
So the Min =4000A - (4000
0.3) = 4000A - 1200A = 2800A
The only value that falls outside the Min/Max range is 2775A < 2800A.
The answer you selected, all values are > 4000A, but less than 5600A.

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