Voltage Transformer Requirements - ABB RELION 670 SERIES Applications Manual

Section 25
Requirements
25.2
25.3
25.4
924

Voltage transformer requirements

The performance of a protection function will depend on the quality of the measured input
signal. Transients caused by capacitive Coupled voltage transformers (CCVTs) can affect
some protection functions.
Magnetic or capacitive voltage transformers can be used.
The capacitive voltage transformers (CCVTs) should fulfill the requirements according to
the IEC 61869-5 standard regarding ferro-resonance and transients. The ferro-resonance
requirements of the CCVTs are specified in chapter 6.502 of the standard.
The transient responses for three different standard transient response classes, T1, T2 and
T3 are specified in chapter 6.503 of the standard. CCVTs according to all classes can be
used.
The protection IED has effective filters for these transients, which gives secure and correct
operation with CCVTs.
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.
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.
1MRK 506 369-UUS -
Line distance protection REL670 2.2 ANSI
Application manual