ABB Relion 670 Series Applications Manual page 594

Section 24
Requirements
During disturbed conditions, the trip security function can cope with high bit error rates up to 10
or even up to 10
differential protection communication supervision, or blocked when COMFAIL is issued after
receive error >100ms. (Default).
Synchronization in SDH systems with G.703 E1 or IEEE C37.94
The G.703 E1, 2 Mbit shall be set according to ITU-T G.803, G.810-13
• One master clock for the actual network
• The actual port Synchronized to the SDH system clock at 2048 kbit
• Synchronization; bit synchronized, synchronized mapping
• Maximum clock deviation <±50 ppm nominal, <±100 ppm operational
• Jitter and Wander according to ITU-T G.823 and G.825
• Buffer memory <250 μs, <100 μs asymmetric difference
• Format.G 704 frame, structured etc.Format.
• No CRC-check
Synchronization in PDH systems connected to SDH systems
• Independent synchronization, asynchronous mapping
• The actual SDH port must be set to allow transmission of the master clock from the PDH-
system via the SDH-system in transparent mode.
• Maximum clock deviation <±50 ppm nominal, <±100 ppm operational
• Jitter and Wander according to ITU-T G.823 and G.825
• Buffer memory <100 μs
• Format: Transparent
• Maximum channel delay
• Loop time <40 ms continuous (2 x 20 ms)
IED with echo synchronization of differential clock (without GPS clock)
• Both channels must have the same route with maximum asymmetry of 0,2-0,5 ms, depending
on set sensitivity of the differential protection.
• A fixed asymmetry can be compensated (setting of asymmetric delay in built in HMI or the
parameter setting tool PST).
IED with GPS clock
• Independent of asymmetry.
24.6 IEC/UCA 61850-9-2LE Merging unit requirements
The merging units that supply the IED with measured values via the process bus must fulfill the
IEC/UCA 61850-9-2LE standard.
This part of the IEC 61850 is specifying "Communication Service Mapping (SCSM) – Sampled
values over ISO/IEC 8802", in other words – sampled data over Ethernet. The 9-2 part of the IEC
61850 protocol uses also definitions from 7-2, "Basic communication structure for substation and
feeder equipment – Abstract communication service interface (ACSI)". The set of functionality
implemented in the IED (IEC/UCA 61850-9-2LE) is a subset of the IEC 61850-9-2. For example the
IED covers the client part of the standard, not the server part.
588
-4
. The trip security can be configured to be independent of COMFAIL from the
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