Long-Time Protective Functions; Short-Time Fu Nctions - GE Power Break II Manual

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 5 0% to 100% of rating p l ug a mps, in 5 % steps. This
setti ng 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 establ ishes the va l ue of "C". For exa mple, a breaker
with a 95% long-time setting and 5 00 a m p rating plug (xi
would have a 475-amp current setting, or value of C.
( Long-time current setting (C)= (0.50 to 1.00) X rati ng plug
Long-time function or c u rrent setting
Long-Time Delay (Standard)
Long-time delay varies the time it will take the brea ker to tri p
under sustained overload conditions. I t perm its the brea ker
to ride through momentary pred icta ble overloads (e.g., mo­
tor starting) without tripping. There are 4 time bands that
provide nominal delays from 3
breakers current setting, or value C.
Long-time de lay
16
(XI)
to 25 seconds at 600 % of the
I nsta ntaneous Function (Standa rd)
All Power Break® I I breakers have e ither the standard in­
stantaneous tr i p function or the "high range" instantaneous
function. The instantaneous trip point esta bl ishes the value
of current that will tri p the brea ker without i ntentional time
delay. Instantaneous tri p times are 50 milliseconds, or less.
I nstantaneous tri ps are the res u lt of severe overcurrent or
short-circuit conditions, and da mage to the power systems is
minimized by immediate tripping. Standard settings are ad­
j ustable i n increments of .5 of X of the r ating plug a m p value
(X). See Table 17.1 for allowable values. The trip u nit will limit
the instar:Jtaneous tri p level so that the breaker withstand
rating is not exceeded.
Standard instantaneous function
Short-Time Fu nctions (Optional)
Short-Time Pickup
The short-time pickup functions controls the level of high
current the brea ker will withsta nd for a short per iod of time
to allow downstream devices to clear faults without
the breaker. Settings are adjusta ble in increments of 50% of
current setting (C). See Table 17.1 for allowa ble
the breaker
values. If the insta ntaneous setting is set for lower values of
current than the short-time function, the instantaneous func­
tion preva i ls.
Short-ti m e pickup function
tri pping
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