ABB RER670 Applications Manual page 493

1MRK 506 375-UEN A
Railway application RER670 2.2 IEC
Application manual
61850-9-2. For example the IED covers the client part of the standard, not the
server part.
The standard does not define the sample rate for data, but in the UCA users group
recommendations there are indicated sample rates that are adopted, by consensus,
in the industry.
There are two sample rates defined: 80 samples/cycle (4000 samples/sec. at 50Hz
or 4800 samples/sec. at 60 Hz) for a merging unit "type1" and 256 samples/cycle
for a merging unit "type2". The IED can receive data rates of 80 samples/cycle.
Note that the IEC/UCA 61850-9-2LE standard does not specify the quality of the
sampled values, only the transportation. Thus, the accuracy of the current and
voltage inputs to the merging unit and the inaccuracy added by the merging unit
must be coordinated with the requirement for actual type of protection function.
Factors influencing the accuracy of the sampled values from the merging unit are
for example anti aliasing filters, frequency range, step response, truncating, A/D
conversion inaccuracy, time tagging accuracy etc.
In principle the accuracy of the current and voltage transformers, together with the
merging unit, shall have the same quality as direct input of currents and voltages.
Section 22
Requirements
487