Operation Of Power+Tm Trip Unites - GE Power Break II Manual

Power+™ Trip Un its
Operation Of Power+ ™ Trip Units
C N
Phases
A B
ptug
urrents
!Optional Neu'b'al Current)
N
""''"
A B C
Bloc k diagram of Power+ trip u n it
Power+ trip units have a variety of standard and optional
functions. The block diagra m shows a ful ly config ured
Power+ trip unit with g round-fault protection. The current
sensors a re special current transformers that provide the trip
unit with its operating power. Interchangeable rating plugs
act as scalars for the outputs of the current sensors, as well
as establish the current rating of individual breakers. When
a four-wire system is used and g round-fa ult p rotection is
called for, an external neutral sensor is necessary.
Ana log current signals a re converted to d ig ita l values, and
a re measured and compa red with established trip settings
in the m icroprocessor's memory. Any overcurrent or g round
fau lt condition that exceeds pre-set conditions produce a trip
signal from the m icroprocessor to the trip actuator. The trip
actuator is a low-energy, positive-action tri pp i n g device. The
low-level trip signal counteracts the strength of the actua­
tor's permanent magnet, and allows a spring to unseal the
magnet an d trip the brea ker.
Both the shunt tri p and undervoltage release (UVR) acces­
sories a lso produce trip signals to the trip actuator when
energized. The two bell ala rms operate only as a result of an
overcurrent trip cond ition.
Power+""
Microprocessor
Fault
Fault
Contact Position Switch
'"With or without lockout
Sta nda rd And Optional Protective Fu nctions
Standard and optional protective functions for Power+
trip units a re shown below. The breaker settings a re pro­
g ra m med in m ultiples of "X" (rating pl ug amp val ues). "S"
(current sensor a m p rating val ues). and "C" (the long-time
setting in a m ps-m u lti ply long-time setting by rating plug
a m p rating).
Standard
•
Adjustable Long-Time (L) Pickup, 0.5 - 1.0X, with fou r delay
bands.
•
Adjusta ble Instantaneous (I) Pickup, 1.5 - 1 5X.*
Options
•
Overload, Short Circuit, and Short-Time local trip indicators
with overload pickup wa rning and health monitors.
•
Adjustable Short-Time (S) Pickup, 1.5 -9.0C, and delay (3
bands) with l2t ON/OFF selection.
•
Adjusta ble Ground Fault (G) Pickup, 02. 0 - 0.6S, and delay*
(3 bands) with 12t ON/OFF selection and trip indicator.
•
U pg radeable Ground Fault function with u se of appropri­
ate g round rating plug.
*
Limited b y breaker frame size a bove ZOOOA.
9