The integrated metering function
can be used with all trip units
with a
Cubicle
BUS
connection. It
not only extends the range of
protection functions of the trip
unit but also provides additional
warnings and diagnostic options.
With its comprehensive range of
measured values, the integrated
WL Circuit Breaker metering
function is an excellent
alternative to external multi-
function metering devices.
General
In addition to the current values
supplied by the trip unit, the
metering function provides the
measured values in the power
distribution system required for
Power Management (voltage, power,
etc.). With its extended protection
function (e.g. undervoltage), the
metering function also provides
further options for monitoring and
protecting the power distribution
system.
The option of generating warnings
if setpoints are exceeded, speeds
up response to system alerts. As a
result, the metering function can
significantly increase system up-time.
The metering function module is
installed on the back of the trip unit
(ETU), as shown in Fig. 2-4. The trip
unit and metering function module
exchange all current data via a high-
speed synchronous interface. The
metering function module provides
all the connected modules (e.g. the
COM15 module or BDA) with the
parameters for the protective relay
functions, the setpoints, measured
value settings, and the measured
values via the
Cubicle
BUS,
so that
they can be processed further. Using
the two
Cubicle
BUS
connections,
the metering function module is
connected to the trip unit and either
the BSS or directly to X7.
The metering function can be
implemented in all circuit breakers
with ETU745, ETU755, ETU748 and
ETU776. If the Metering Function
module or Metering Function PLUS
module are ordered with the
assembled circuit breaker, it will
already be installed and ready for
operation. The metering function
(and metering function Plus) can be
retrofitted at any time if the circuit
breaker is equipped with one of the
trip units listed above. It is simply
screwed onto the trip unit and the
Cubicle
BUS
lines are snapped in.
Note:
If installed by the customer,
the metering function is not
calibrated with the trip unit;
therefore, the accuracy of the
specifications in Table 2-7 cannot
be guaranteed.
Communication-capable Circuit Breakers
Metering Function and Metering Function
Plus
2/13
Figure
2-4
The Metering Function/Metering Function Plus is located on the back of the trip unit.
When ordered as part of an assembled breaker catalog number, it is already installed
and ready for operation.
WL Circuit Breaker
Chart 2-1
Voltage Transformer Specifications for Metering
ITI VT Model
System
Voltage Turns
Number *
Rating
Rating Ratio
(or equivalent)
600V 3P 3W Delta
600:120
5:1 450-600
480V 3P 3W Delta
480:120
4:1
450-480
240V 3P 3W Delta
240:120
2:1
450-240
600Y/347V 3P 4W
346:120
2.88:1
450-36
480Y/277V 3P 4W
288:120
2.4:1
450-288
*External fuses are recommended with these VT’s.
WL PROFIBUS Communication and Electronic Accessories • July 2004
