MicroVersaTrip Plus™ and PM™ Trip Units
Long-Time Protective Functions
Long-Time Function/Current Setting (Standard)
The adjustable long-time setting is based on multiples of
"X", the rating plug a m p rating. There are 11 possible setting
from 50% to 100% of rating plug amps, in 5% steps. This
setting establishes the current setting of the breaker, which
is the current the breaker will carry continuously without
tr ipping. Multiplying the long-time setting by the rating plug
value establishes the value of "C". For example, a breaker
with a 95% long-time setting and 500 amp rating plug (xi
would have a 475-amp current setting, or value of C.
( Long-time current setting (C)= (0.50 to1.00) X rating plug
(XI)
Long-time function or current setting
Long-Time Delay (Standard)
Long-time delay varies the time it will take the breaker to trip
under sustained overload conditions. It permits the breaker
to ride through momentary predictable overloads (e.g., mo
tor starting) without tripping. There are 4 time bands that
provide nominal delays from 3
to
25
seconds at
600 %
of the
breakers current setting, or value C.
Long-time delay
16
I nstantaneous Function (Standard)
All Power Break® I I breakers have either the standard in
stantaneous tr i p function or the "high range" instantaneous
function. The instantaneous trip point establishes the value
of current that will tri p the breaker without i ntentional time
delay. Instantaneous trip times are 50 milliseconds, or less.
I nstantaneous tri ps are the result of severe overcurrent or
short-circuit conditions, and damage to the power systems is
minimized by immediate tripping. Standard settings are ad
justable in increments of .5 of X of the r ating plug amp value
(X). See Table 17.1 for allowable values. The trip unit will limit
the instar:Jtaneous tri p level so that the breaker withstand
rating is not exceeded.
Standard instantaneous function
Short-Time Functions (Optional)
Short-Time Pickup
The short-time pickup functions controls the level of high
current the breaker will withstand for a short per iod of time
to allow downstream devices to clear faults without
tripping
the breaker. Settings are adjustable in increments of 50% of
the breaker
current setting (C). See Table 17.1 for allowable
values. If the instantaneous setting is set for lower values of
current than the short-time function, the instantaneous func
tion prevails.
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Short-time pickup function
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