MicroVersaTripPius
rM
and PM™ Trip Units
Defeatable Ground-Fault Protection (Optiona ll
Not U L Listed
A defeatoble ground-fault protection is offered for users who
wont the ability to enable or disable ground-fault protec
tion depending on special circumstances. When this type of
g round-fault protection is ordered, in addition to the normal
ground-fault settings, the user con enable or disable ground
fault protection d u ring programming. To disable this kind of
ground-fault protection, set the delay to OFF.
Zone Selective I nterlocking (Optional)
Traditional means of obtaining selectivity between main and
feeder breakers is to set the furthest downstream device
with the lowest time delays, and increase time delays of
u pstream devices. The disadvantage of this is that u pstream
portions of the system must endure high values of fau lt cur
rent until time-out occurs.
"Output" from Trip unit
"Input" to Trip unit
ZSIM
Downstream
Upstream
Connections
Connections
- Bus
--
Wiring
M ulti-zone selective interlocking
MicroVersoTrip Plus™ and MicroVersoTrip PM™ trip units
provide coordination between the first breaker and the im
mediate u pstream breaker. When the downstream breaker
detects a fault, it signals the upstream device to shift to its
preset time delay bond, a l lowing the downstream device to
clear the fault. Without a signal from a downstream brea ker,
on u pstream breaker will respond on the minimum delay
bond. For a fau lt between these two breakers, the upstream
would clear the fault on the minimum delay bond since no
signal is being sent by the downstream breaker.
Zone Selective interlocking is ava i lable for either ground fault
only, or both g round-fault and short-time functions. The
zone selective interlocking feature requires a zone selective
interlock module (ZSI M) catalog number TI M l. The module is
on intermediate control device used between upstream and
downstream circuit breakers to communicate with the short
time and ground-fault zone selective interlock functions of
the M icroVersoTrip Plus and MicroVersoTrip PM units. The
module req uires 120/208/240 VAC, 15 VA maximum.
Operation of MicroVersaTrip PM Trip Units
M icroVersoTrip PM trip units odd communications capability
with remote h ost computers and the G E POWER LEADERTM
Power Management System. I n addition, the user can choose
to odd metering, protective relaying or both. In the block dia
gram (page 20) of the M icroVersoTrip PM trip unit, note that
there ore two a dditional sets of inputs- voltage inputs from
each p hose a n d a +24 Vdc input from on external power
supply. Additionally, there is a communication input/output
link to the POWER LEADER system.
Voltage I nputs
Voltage inputs to the MicroVersoTrip PM trip unit ore required
for both metering and protective relays. Voltage inputs
require three delta or wye-connected potential transformers
with 120 Voc secondaries, and an external voltage module
that further conditions the voltage signals for use by the trip
unit's microprocessor. A single set of external voltage mod
ules con serve the requirements of up to 20 trip units.
19
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