Which curve in the figure shown represents inverse time characteristics?
Your Answer: Curve B
Correct Answer: Curve A
Help: Characteristics of Circuit Breaker Trip Curves and Coordination
Both A and B are inverse time. From IEEE 100:
inverse time (1) (as applied to circuit breakers) A qualifying
term indicating there is purposely introduced a delay in the
tripping action of the circuit breaker, which delay decreases
as the magnitude of the current increases.
(2) See also: inverse-time relay.
…
inverse-time relay A relay in which the input quantity and operating
time are inversely related throughout at least a substantial
portion of the performance range. Note: Types of inverse-
time relays are frequently identified by such modifying
adjectives as “definite minimum time,” “moderately,” “very,”
and “extremely” to identify relative degree of inverseness of
the operating characteristics of a given manufacturer’s line of
such relays.
