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IB 6.2.11.1-2C
Page 9
four "b" contacts (with three "a" and two "b" contacts
available
for
customer
disconnects).
The
interconnected with the circuit breaker mechanism such
that, with the circuit breaker closed, the "a" contacts are
closed and the "b" contacts are open. With the circuit
breaker open, the "a" and "b" contacts reverse
positions.
This switch is located in the lower right
portion of the circuit breaker.
Optionally, EO breakers and MO breakers with shunt
trip can be fitted with a 16-pole switch, which offers an
additional four each "a" and "b" contacts for customer
use.
Undervoltage Trip Device (Optional) - The electrically
reset undervoltage trip device (UVD) is a single-phase
device which automatically trips the circuit breaker
when the supplied voltage decreases to 30 to 60
percent of the rated voltage.
furnished either for instantaneous trip operation or with
adjustable time delay tripping of 1.5-15 seconds. The
undervoltage trip device is an integral unit which may
be added to the circuit breaker either at the factory or in
the field.
See Table 3 for electrical characteristics of the UVD.
MPSC-2000 SOLID STATE TRIP SYSTEM
The MPSC-2000 electronic, microprocessor-based trip
system
includes
the
electronic trip device, the magnetic latch, and the
interconnecting wiring. A current sensor is integrally
mounted on each phase of the circuit breaker to supply
a value of current flowing in the trip unit which is
directly proportional to the current passing through the
primary circuit.
When the value of current in the
primaries exceeds the trip unit threshold setting for a
Table 3
Figure 3 - Undervoltage Trip Device
Operating Data
Current at
Service Voltage
Rated
Voltage
120VAC (60 Hz)
0.5A
240VAC (60 Hz)
0.2A
480VAC (60 Hz)
0.1A
48VDC
0.3A
125VDC
0.2A
250VDC
0.1A
use
via
the
secondary
switch
is
mechanically
This device may be
sensors,
the
MPSC-2000
Maximum
Dropout
Pickup
Voltage
Voltage
Range
102
36-72
204
72-144
408
144-288
41
15-29
106
38-75
212
75-150
given time in long time, short time, and/or ground, then
tripping occurs by sending a signal to the magnetic
latch.
Instantaneous tripping occurs in the same
manner, but without the time delay. On three phase,
four wire, wye systems, provisions are made for input
from a separately mounted sensor to obtain a residual
connection of all four sensors for sensitivity to ground
currents.
The MPSC-2000 trip unit (Item 3 of Figure 1) is visible
on the front of the circuit breaker. It is completely self-
powered, taking the tripping energy from the primary
current passing through the circuit breaker without the
need for any additional power supply. An external 9V
battery is supplied to permit the user to access the
MPSC-2000's menus. The battery is not required for
correct operation of the trip device. The battery will last
only about 1-2 hours of actual use, so the switch to this
battery should be left in the "off" position except when
needed.
To cope with modern power systems where harmonics
in
the
system
can
overheating, the MPSC-2000 long time trip element
samples the current in a unique algorithm, then
calculates the root mean square (RMS) value of the
system current, providing tripping when the RMS
current is above the trip threshold.
cable and busway is thus avoided with the MPSC-2000
trip system.
Short time and Instantaneous tripping
remains based on peak sensing methods, avoiding
unnecessary delay in tripping caused by the RMS
calculation.
The MPSC-2000 trip system also includes all the
connection
ports
and
communication duties when connected to the PRICOM
or PRICOM-PLUS communication systems. Although
a breaker might not be connected to a communication
system when it is installed, it will not require any
modification to be connected to the Network Interface
Module (NIM) in the PRICOM system at some future
time. This unique feature allows for future expansion
without incurring additional up-front expenses.
NIM cable is connected to the nine-pin connector
adjacent to the 25-pin connector on the end of the
MPSC-2000 trip device. If the device is configured with
a Voltage Interface Module (VIM), a four pin connector
will also be adjacent to the previously mentioned
connectors. See bulletin 3.1.3-2A for additional details
about the PRICOM communication system.
Four basic elements within the MPSC-2000 trip unit
perform the protective functions:
short time, (3) instantaneous, and (4) ground. Each of
these may be disabled or adjusted independently,
except for a few conditions which are required to
ABB
cause
cable
and
busway
Overheating in
software
for
performing
(1) long time, (2)
The
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