MicroVersaTrip Plus™ and PM™ Trip Units
Operation of MicroVersaTrip Plus™
Trip Units
PhllSeS
A 8 C
N PTs With
120 ViK
Set;OOdaries
Zone Selective Interlock
A
B
C
N
Phases
(Optional)
24 Vdc
Power Supply
MicroVersaTrip PM
Microprocessor
•With or without lockout
Block diagram of MicroVersaTrip Plus trip unit
MicroVersoTrip Plus units have a menu of standard and op
tional functions. The block diagram shows a fully configured
MicroVersaTrip Plus tri p unit with ground-fault protection.
The current sensors are specia l curre nt transformers that
provide the trip unit with its operating power. I nterchange
able ratings 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 a
ground-fault protection is called for, a n exter nal neutral sen
sor is necessary.
Analog current signals ore converted to digital values, and
are measured and compared with established trip settings
in the microprocessor 's memory. Any overcurrent or ground
fault condition that exceeds pre-set conditions produces a
tr ip signal from the microprocessor to the trip actuator. The
trip actuator is a low-energy, positive-action tripping device.
The low-level trip signal counteracts the strength of the
actuator's per manent magnet, and allows a spring to unseal
the magnet and tr ip the brea ker.
Both the shunt tri p and undervoltage release (UVR) acces
sories also produce trip signals to the tr ip actuator when en
ergized. The user may program each of the two bell alar ms,
independently, to operate as a result of any combination of
overcurrent (including ground fault). shunt tr ip and under
voltage release.
Standard And Optional Protective Functions
Standard and optional protective functions for MicroVersa
Trip Plus trip units are shown below. The breaker settings are
programmed in m ultiples of "X" (rating plug amp values). "S"
(current sensor amp rating values). "C" (the long-time setting
in amps - multiply long-time setting by rating plug amp r at
ing). and "H" (the short-time withstand rating of the breaker).
Standard
•
3-phose Ammeter
•
Adjustable Long-Time ( L) pickup, 0.5 - LOX, with four
delay bands
•
Adjustable instantaneous
(I)
pickup, 1.5 - 15X
•
Overload, Short Circuit, and Short-Time local tri p indicators
with overload pickup warning
•
Test set initiated trip
Optional Functions
•
Adjustable Short-Time (S) pickup, 1.0 -9.0C and delay
(3 bands) with l2t ON/OFF selection
•
Adjustable Ground Fault (G) pickup, 0.2-0.6S and delay
(3 bands) with l2t On/Off selection and tr ip indicator
•
High-range instantaneous fixed at 1.0H
•
Zone selective inter locking for Ground Fault or Ground
Fault and Short-Time
•
Defeotable Ground Fault function (non-UL)
15
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