SVCB attribute Description
NoAsdu Number of ASDUs, which are concatenated into
one APDU.
IncludeRefreshTime If selected SV buffer contains the attribute
“RefrTm”.
IncludeSampleRate If selected SV buffer contains the attribute
“SmpRate”.
Modify only MAC address, VLAN ID and sampled value ID to keep
the 9-2 LE compliancy. Leave the others as default.
6.4.3 Angle and amplitude corrections
The TxTR instrument transformer amplitude correction factors also affect the scaling
in SMV frames. Thus, it is sufficient to configure these correction factors in the sender
only. The angle correction factors on the other hand affect only the fundamental
frequency phasor and they need to be set in both the SMV sender and the receiver
analog input configuration.
6.4.4 SMV delay
The SMV Max Delay parameter, found via menu path Configuration/System, defines
how long the receiver waits for the SMV frames before activating the TxTR ALARM
output. This setting also delays the local measurements of the receiver to keep them
correctly time aligned. The SMV Max Delay values include sampling, processing and
network delay.
TxTR ALARM activates when two or more consecutive SMV frames are lost or late. A
single loss of frame is corrected with a zero-order hold scheme, the affect on
protection is considered negligible in this case and it does not activate the TxTR
WARNING or ALARM outputs.
Table 9: Topology-dependent SMV max delay setting
Number of
hops in
network
Internal
application
delay (µs)
(50Hz)
Internal
switch
delay (µs)
Store and
forward
latency (µs)
Queue
latency
(µs)
1)
Additional
tolerance
(µs)
2)
Theoretical
max delay
(µs)
Recommen
ded max
delay
setting (µs)
2
1746 20 24 240 80 2112 3150
5 1746 50 60 600 200 2656 3150
10 1746 100 120 1200 250 3416 3150
15 1746 150 180 1800 300 4176 3150
Table continues on next page
1MRS757809 C Section 6
Process bus and IEEE 1588 time synchronization
REC615 and RER615 73
Engineering Guide
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