H Igh-Range I Nstanta Neous; Normal G Rou Nd-Fa U Lt Protection - GE Power Break II Manual

MicroVersaTripPius™ and PM™ Trip Units
Short-Time Delay
Short-time delay is a lways provided when short-time picku p
is ordered. Short-time delay provides additional refi nement in
providing coordination between upstream and downstream
protective devices. There a re three time delays that provide
delays from 100 ms to 350 ms of 1 (MI N), 2 (I NT), 3(MAX).
Short-time delay wit h 12t OUT
Selectable Short Time (2t Function
Selecta ble short-time l2t is a lways provided with the short­
ti me option. The l2t h e l ps the solid-state trip unit coordinate
with downstream thermal mag netic devices or fuses. This
function i m pacts the shape of short-ti me and short-ti me
delay time current curves, and may be prog rammed either
I N or OUT.
Short-time delay with l2t I N
H igh-Range I nsta nta neous (Optional)
The hig h-range instantaneous function is for special applica­
tions where all coordination is ba sed on adjustments of long
and short time. The instantaneous trip setting is fixed at "H"
- breaker's short-time withstand rati ng.
Normal G rou nd-Fault Protection (Optional)
Ground-Fault Protection
A g round fault is an unintentional current flow from a circuit
through a conductive path to g round. Ground fau lts usu­
ally have interm ittent or very low values of current flow,
as depicted in G ra ph A, and a re not detected by long-time
overload protection.
18
1 r
u
l r
ll
�
l't
OUT
II
!"--1
t'·i
Some g rou nd-fault trip systems may not detect this typ e
o f fa ult because t h e intermittent nature o f the fault never
exceeds the trip threshold as illustrated in Gra ph B.
The MicroVersaTrip Pl us™ and MicroVersaTrip PM™ trip u nits
detect and integ rate (add a series of a rcing and interm ittent
current pulses) the low-level current of a g round fault. This
integration function provides a memory response for g round
fa ults to ach ieve p referred g round fa ult protection a s s hown
in G raph C.
The N EC requi res that the maxi mum g rou nd-fault setti n g not
exceed 1200 am ps. G round-fa ult protection includes pickup
setting, g round-fa ult delay settings and selectable l2t func­
tion.
Ground fault memory c i rcuit
G round fau lt pickup and ground fau lt time delay
G round-fault pickup settings a re based on multiples of S,
the current sensor rating. The lowest setting is 20% of S, and
the hig hest setting is based o n current sensor amp ratings,
such that the maximum setting does not exceed 1200 a m ps.
There a re three ground-fault delay bands of 1 ( M I N), 2 (I NT) 3
(MAX) ra nging from 100 ms to 350 ms. The l2t function adds
an 12t slope to the sq uare corner of the g round-fault time
current curve transition, from pickup to the constant delay
bands, to improve coordi nation with downstream devices.