Communication-capable Circuit Breakers
Digital Input Module
Functional description
The digital input module enables up
to six additional binary signals (24V
DC) to be connected. Signals, such
as the status of the breaker, the
status of the switchgear cabinet
door, or a signal indicating that a
predefined temperature has been
exceeded, can be transmitted
directly and processed at the field
bus level.
A total of 6 inputs are available
in the “BUS Input” Switch position.
Six inputs are also available if the
rotary switch is in the “Parameter
Switch” position, although the first
input causes the active parameter
set to change. If the connected ETU
does not have two parameter set
capability (e.g. ETU745 or ETU748),
this input
can also be used without any
restrictions.
Functional description for
changing parameter sets
Trip units ETU755 and ETU776 have
two different parameter sets for the
protection function. This function is
particularly useful in the event of a
power failure when an automatic
transfer is made from utility to
generator, a process which may
require that all the protective
functions change.
The PROFIBUS communication
system, the BDA, the ETU776
display, or the digital input module
can be used to switch between the
two parameter sets.
For this purpose, the first module
input is used in the “Parameter
Switch” position on the rotary
switch. If a “1” signal is detected
(LED on input 1 is yellow), the
switchover to parameter set B is
communicated to the trip unit. If
the input signal switches back to
“0”, the switchover to parameter
set A is communicated, and the
LED on input 1 is de-energized.
Since the
Cubicle
BUS
is event
controlled, trip unit ETU755 or
ETU776 switches over to the other
parameter set when a switchover
request is issued via the
Cubicle
BUS
.
This means that if a switchover is
made to parameter set B via the
BDA, for example, even though the
input on the digital input module
is set to “0” (parameter set A), the
active parameter set in the trip
unit switches to parameter set B.
A switchover event to parameter set
A is not initiated on the
Cubicle
BUS
until the input on the digital input
module is set first to “1” and then
back to “0.”
A maximum of two digital input
modules can be operated
simultaneously on one WL Circuit
Breaker: one as a module with the
“BUS Input” position and the other
as “Parameter Switch” mode.
2/24
Table 2-15
This table provides accurate technical data for the digital input module on the
Cubicle
BUS
.
Operating voltage min. / max.
19.2V / 28.8V
Operating current min. / max.
29mA / 43mA
No. of channels per digital input module
6
Min. voltage value for detecting a “1” signal
>16V
Current per input for a “1” signal
7.5mA
Max. voltage value for detecting a “0” signal
<1V
Current input per input for a “0” signal
0mA
Max. no. of digital input modules per breaker
2
Power min. / max.
0.72W / 0.94W
Dimensions W / H / D
70mm / 86mm /95mm
Weight
0.223 kg
Operating temperature range
-20°C / 60°C
Technical data for the digital input module
WL Circuit Breaker
The position of the rotary
switch determines the
operating mode.
Figure
2-13
WL PROFIBUS Communication and Electronic Accessories • July 2004
