ABB RELION REX640 Technical Manual page 1499

Protection and control

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1MRS759142 F

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.

Operation principle

The function can be enabled and disabled with 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

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

Technical Manual

Measurement functions

Operation setting. The