Hitachi Relion 670 Series Applications Manual page 426

Section 22
Requirements
22.3 SNTP server requirements
The SNTP server to be used is connected to the local network, that is not more than 4-5 switches or
routers away from the IED. The SNTP server is dedicated for its task, or at least equipped with a
real-time operating system, that is not a PC with SNTP server software. The SNTP server should be
stable, that is, either synchronized from a stable source like GPS, or local without synchronization.
Using a local SNTP server without synchronization as primary or secondary server in a redundant
configuration is not recommended.
22.4 PTP requirements
For PTP to perform properly, the Ethernet equipment that is used needs to be compliant with
IEEE1588. The clocks used must follow the IEEE1588 standard BMC (Best Master Algorithm) and
shall, for instance, not claim class 7 for a longer time than it can guarantee 1us absolute accuracy.
22.5 Sample specification of communication requirements
for the protection and control terminals in digital
telecommunication networks
The communication 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) for high availability of the differential protection
•
<10
•
<10
During disturbed conditions, the trip security function can cope with high bit error rates up to 10
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
420
The IED supports SNTPv4 (RFC2030).
-6
according to the standard for data and voice transfer
-8 -9
-10 during normal operation
-6
during disturbed operation
-4
. The trip security can be configured to be independent of COMFAIL from the
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