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

Power+™ Trip Units

Long-Time Protective Functions

I
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 7 possible settings from
50% to 100% of rating plug a m ps. This setting establishes
the current setting of the breaker, which is the current the
breaker will carry continuously without trippi n g. M u ltiplying
the long-time setting by the rating plug va lue establishes the
value of "C". For exa mple, a breaker with a 95% long-time
setting and 500-amp rating plug (X), would have a 475-amp
current setting, or value of C.
( Long-time current setting (C)= (0.50 to 1.00) x rating plug (X))
7
.8
Long-time function or c u rrent setting
Long-Time Delay (Standard)
Long-time delay varies the time it wil l take the brea ker to tri p
under sustained overload conditions. I t permits the breaker
to ride thro ugh momentary pred icta ble overloads (e.g., mo­
tor starting) without tri pping. There are 4 time bands that
provide nominal delays from 3 to 25 seconds at 600% of the
setting, or value of C.
breaker's current
Long-time delay
10
I n sta ntaneous Function (with Power+ Trip U n its)
All Power Break® II breakers have the standard instanta­
neous tri p function. The instantaneous tri p point esta blishes
the value of current that will tri p the brea ker without inten­
tional time delay. Instantaneous tri p times are 50 millisec­
onds, or less. Instantaneous trips are the result of severe
overcurrent or short-circuit conditions. and damage to the
power system is m inimized by immediate tripping. Stand ard
setting s are a djusta ble in multiples of the rating plug amp
value (X). See Ta ble 11.1 for a l lowa ble values. The trip unit will
limit the instantaneous tri p level so that the breaker with­
stand r ating is not exceeded. Maximum setting is dependent
on breaker frame size.
1.5
1 0 I 9
Standard instantaneous function
Short-Time Functions (Optional)
Short-Time Pickup
The short-time pickup function controls the level of high cur­
rent the breaker will withstand for short periods of time to
al low downstream devices to clear fau lts without tri pping the
breaker. Settings are a dj ustable in increments of the breaker
(C).
nt
curre settin g See Table 11.1
instantaneous setting is set for lower values of current than
the short-time function. the instantaneous function prevails.
, - 1 - . 5
I
2. 5
I
S h o rt-time pickup function
for allowable val ues. the
If