Appendix; Sample Specification Of Communication Requirements - Hitachi 670 Series Application Manual

1MRK505382-UEN Rev. K
Section 6
6.1

Sample specification of communication requirements

This chapter provides a sample specification of communication requirements for line differential
protection IEDs in telecommunication networks. The requirements are based on echo timing.
Bit error rate (BER) according to ITU-T G.821, G.826 and G.828
•
< 10
Bit error rate (BER) with high availability of the line differential protection
IED
•
< 10
•
< 10
Synchronization in SDH systems with G.703 E1 or IEEE C37.94
G.703 E1 (2 Mbit/s) is set according to ITU-T G.803, G.810-13.
• One master clock for the actual network
• Actual port synchronized from 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
• G.704 frame format: structured, unstructured, and so on
• No CRC check
Synchronization in PDH systems connected to SDH systems
• Independent synchronization, asynchronous mapping
• Actual SDH port set to allow transmission of the master clock from the PDH network (SDH
network 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: <1 00 μs
• Format: transparent
• Maximum channel delay
• Loop time: < 40 ms continuous (2 x 20 ms)
Line differential protection IED with echo synchronization (no GPS clock)
• Both channels to have the same route with maximum asymmetry of 0.2–0.5 ms depending on
the set sensitivity of the line differential protection function
• Fixed asymmetry can be compensated for by setting the AsymDelay on the local HMI or via PST
Line differential protection IED with GPS synchronization (GPS clock)
• Independent of asymmetry
Communication set-up, 670/650 series
Application Guide

Appendix

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according to the standard for data and voice transfer
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to 10 during normal operation
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during disturbed operation
During disturbed operation, the trip security function in the line differential protection IED
can cope with high bit error rates up to 10
configured to be independent from COMFAIL of the line differential protection
communication supervision, or it can be blocked when COMFAIL is issued after receive
error > 100 ms (default).
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or even up to 10 . Trip security can be
Section 6
Appendix
93