ABB Relion 670 Series Application Manual page 22

Section 2
Telecommunication networks and line differential protection
DeadbandtDiff setting range is ±200-1000 μs. If the accumulated time delay of up to four
The
changes is greater then the set value for
MaxtDiffLevel , no action is taken. When the fifth time delay change occurs, the protection
function is blocked even if the maximum deviation is not reached. This restriction is included
because of measuring inaccuracy with too many consecutive, accumulated time delay
changes. After blocking, the communication set-up must be checked before restarting.
IEC10000062 V1 EN-US
Figure 6:
Figure 7
scattering (deviation in calculation) within the set
IEC07000226 V1 EN-US
Figure 7:
D
dt
Scattering
16
Setting DeadbandtDiff in PCM600
shows an oscillogram example of deadband, measured change in time delay and
An oscillogram example showing deadband (D), measured change in time
delay (dt) and scattering
DeadbandtDiff = ±200 μs
Measured time delay change = ±200 μs
Random fluctuations in time delay due to, for example, varying switching time in
multiplexers that induces jitter and wander.
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DeadbandtDiff but below the set value for
DeadbandtDiff value.
Communication set-up, 670/650 series
1MRK 505 382-UEN E
dt
D
IEC07000226-1-en.vsdx
Application Guide