ABB RET 54 Series Technical Reference Manual, General page 54

RET 54_
54
Transformer Terminal
Technical Reference Manual, General
absolute value of the input. The linearization curves can be enabled and disabled
with the Linear. curve parameters in the menu
Configuration/RTD1/Input #.
Parameter
Linear.curve 0=Disabled
The curve is constructed for the transformer terminal by using the Transducer
Linearization Tool (TLT) in the relay tool package CAP 505 .Figure 5.1.9.5.-1
shows an example construction.
When the linearization curve is enabled, the Input high limit and
Input low limit parameters define the scaled range instead of the range
selected by the original range parameters. The range of the scaled input is defined as
the range between the smallest y-axis value and the largest y-axis value.
Application example for tap changer position linearization
In this example, the transformer tap changer position indication is wired as a mA
signal from the corresponding measuring transducer and connected to input 1 of the
RTD1 card. The tap changer has been controlled through the whole operating area,
from minimum to maximum turns of tap, and a corresponding mA signal for the tap
position has been measured.
Table 5.1.9.5-1 Example of tap changer mA measurements
Measurement TAP_POS
1 1
2 3
3 5
4 7
5 9
6 11
7 13
8 15
9 17
10 19
The range to be linearized should be selected from the relay settings before
linearizing. In this way, the TLT knows the original range to be linearized.
The TLT allows for a maximum of ten points to be linearized. If the range is already
linear, but in a different scale, then only the low and the high points are needed for
linearizing. The following picture shows how values are added into TLT.
Values Default
Disabled
1=Enabled
POS (mA)
4,85
6,54
8,23
9,98
11,60
13,28
14,96
16,64
18,33
20,01
1MRS755225