Section 4 Binary input and output modules
4.1 Binary input
4.1.1 Binary input debounce filter
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The debounce filter eliminates bounces and short disturbances on a binary input.
A time counter is used for filtering. The time counter is increased once in a
millisecond when a binary input is high, or decreased when a binary input is low. A
new debounced binary input signal is forwarded when the time counter reaches the
set DebounceTime value and the debounced input value is high or when the time
counter reaches 0 and the debounced input value is low. The default setting of
DebounceTime is 1 ms.
The binary input ON-event gets the time stamp of the first rising edge, after which
the counter does not reach 0 again. The same happens when the signal goes down
to 0 again.
4.1.2 Oscillation filter
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Binary input wiring can be very long in substations and there are electromagnetic
fields from for example nearby breakers. An oscillation filter is used to reduce the
disturbance from the system when a binary input starts oscillating.
An oscillation counter counts the debounced signal state changes during 1 s. If the
counter value is greater than the set value OscBlock, the input signal is blocked.
The input signal is ignored until the oscillation counter value during 1 s is below
the set value OscRelease.
4.1.3 Settings
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OscBlock must always be set to a value greater than OscRelease. If
this is not done, oscillation detection will not function correctly, and
the resulting behaviour will be undefined.
1MRK 505 394-UEN A Section 4
Binary input and output modules
Line differential protection RED650 2.2 IEC 59
Technical manual
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