Communication-capable Circuit Breakers
The ability to change between
two different parameter sets is also
possible. This function is particularly
useful in the event of a power
failure when an automatic transfer
is made from utility to generator
power, a process which can
involve changing many of the
trip unit parameters.
A wide range of lock-out systems
are available to improve reliability
during critical processes. All
accessories, such as shunt trips,
motor operators and communication
components, can be installed
quickly and easily; this is made
easier because the accessories are
identical across the entire product
line. The commitment to reducing
the overall number of parts results
in fewer spares to be ordered and
lower inventory costs.
The heart of each circuit breaker
is the electronic trip unit (ETU).
Several versions are available to
adapt the protective, metering,
and alarm functions to the system
requirements: from simple overload
and short-circuit protection to trip
units that can be configured
remotely and which feature a
wide range of metering and alarm
functions.
All circuit breakers with ETU745,
ETU748, ETU755 and ETU776
trip units are communications
capable, and allow additional
components to be internally
networked via the
Cubicle
BUS
.
The circuit breaker is connected to
PROFIBUS via the RS485 interface
on the COM15 module.
The breaker data adapter (BDA)
(see Chapter 4) also supports
higher-level networking/
communication (Intranet/Internet).
The
Cubicle
BUS
The
Cubicle
BUS
, which connects all
the intelligent components within
the WL Circuit Breaker and enables
additional external components to
be connected quickly and reliably,
forms the backbone of the modular
architecture of the WL. The
Cubicle
BUS
is already integrated
in and connected to all assembled
circuit breakers with the ETU745,
ETU748, ETU755, and ETU776
trip units.
The high level of system modularity
enables communication functions
(e.g. metering function) to be
retrofitted at any time. A WL Circuit
Breaker that is not communications
capable can be upgraded (e.g. by
exchanging ETU72
5
for ETU745
with
Cubicle
BUS
) quickly and easily
on site. All
Cubicle
BUS
modules
can access the existing data of the
circuit breaker directly, thereby
ensuring rapid access to information
and speedy responses to events.
By connecting additional, external
modules to the
Cubicle
BUS
,
cost-effective solutions for
communicating data from other
devices in the cubicle can be
implemented.
Communications Capability of the
Electronic Trip Units (ETUs)
The electronic trip units ETU745,
ETU748, ETU755, and ETU776 are
all communications capable. The
Cubicle
BUS
is connected to the
circuit breaker terminals X8.1(-)
to X8.4(+)
Different versions of
communications-capable trip
units are available.
The front of the ETU745 has rotary
switches for setting protective
parameters. These can be read via
the communication device. The
ETU745 can also be installed with
a four-line display for the measured
values.
The ETU755 does not have rotary
switches or a display. The protective
parameters can only be changed
via communications. This trip unit
with remote-only parameter setting
is for special application demands.
The ETU776 features a graphical
display with a clearly structured,
key-driven menu. This not only
enables operators to display
measured values, status information,
and maintenance information,
but also to read all the existing
parameters and make password-
protected changes.
2/2
WL Circuit Breaker
WL PROFIBUS Communication and Electronic Accessories • July 2004
