ABB RELION REX640, Техническое руководство, Страница: 1499 / 1960

There are three user-selectable conversion modes available for the 7-bit binary
inputs where MSB is used as the SIGN bit: the natural binary-coded boolean input
to the signed integer output, binary coded decimal BCD input to the signed integer
output and binary reflected GRAY coded input to the signed integer output.
8.5.4 Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off". When the function is disabled,
the tap position quality information is changed accordingly. When the tap position
information is not available, it is recommended to disable this function with the
Operation setting.
The operation of TPOSYLTC can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
Figure 821: Functional module diagram
Tap position decoder
When there is a wired connection to the
TAP_POS
input connector, the
corresponding tap changer position is decoded from the
mA
or
RTD
input. When
there is no wired connection to the
TAP_POS
connector, the binary inputs are
expected to be used for the tap changer position information. The tap changer
position value and quality are internally shared to other functions. The value is
available in the Monitored data view or as a
TAP_POS
output signal.
The function has three alternative user selectable operation modes: "NAT2INT",
"BCD2INT" and "GRAY2INT". The operation mode is selected with the
Operation
mode setting. Each operation mode can be used to convert a maximum of 6–bit
coded input to an 8–bit signed short integer output. For less than 6–bit input, for
example 19 positions with 5 bits when the BCD coding is used, the rest of the bits
can be set to
FALSE
(0).
The operation mode "NAT2INT" is selected when the natural binary coding is used
for showing the position of the transformer tap changer. The basic principle of the
natural binary coding is to calculate the sum of the bits set to
TRUE
(1). The LSB has
the factor 1. Each following bit has the previous factor multiplied by 2. This is also
called dual coding.
The operation mode "BCD2INT" is selected when the binary-coded decimal coding is
used for showing the position of the transformer tap changer. The basic principle
1MRS759142 F Measurement functions
REX640
Technical Manual
1499