Date Code 20171006 Instruction Manual SEL-400 Series Relays
Instruction ManualInstruction Manual
SECTION 11
Time and Date Management
SEL-400 series relays can determine the time from a variety of sources, including
IRIG-B, PTP (IEEE 1588), Simple Network Time Protocol (SNTP), DNP3, M
IR-
RORED BITS, terminal TIME and DATE commands, and HMI settings. (Refer to
the appropriate sections in the product-specific instruction manual to learn about
using these various time sources.) Most of these sources provide only an approx-
imate measure of time. For high-accuracy time synchronization, which is needed
to support synchrophasors and to ease comparison of system-wide events, a high-
accuracy time source must be provided, such as IRIG-B with C37.118 extensions
or PTP with power system profile. This section focuses on issues related to high-
accuracy timekeeping. The relay records power system events with very high
accuracy when you provide high-accuracy clock input signals. Relays placed at
key substations can give you information on power system operating conditions
in real time.
NOTE: Not all SEL-400 series relays
support synchrophasors.
Based on the high-accuracy time input, the relay calculates synchrophasors for
currents and line voltages (for each phase and for positive-sequence), as specified
in IEEE C37.118, Standard for Synchrophasor Measurements for Power Sys-
tems. You can then perform detailed analysis and calculate load flow from the
synchrophasors. See Section 18: Synchrophasors for more information about
phasor measurement functions in the relay.
This section presents details on these measurements as well as suggestions for
further application areas. The topics of this section are the following:
➤ IRIG-B Timekeeping on page 11.1
➤ PTP Timekeeping on page 11.2
➤ Time Source Selection on page 11.4
➤ Time Quality Indications on page 11.5
➤ Time-Synchronized Events on page 11.9
IRIG-B Timekeeping
The relay is capable of high-accuracy timekeeping when supplied with an
IRIG-B signal. When the supplied clock signal is sufficiently accurate, the relay
can act as a phasor measurement unit (PMU) and transmit synchrophasor data
representative of the power system at fixed time periods to an external data pro-
cessor. The relay can also record COMTRADE event report data using the high-
accuracy time stamp.
The relay has two input connectors that accept IRIG-B demodulated time-code
format: the IRIG-B pins of Serial Port 1, and the IRIG-B BNC connector. See
Section 2: Installation in the product-specific instruction manual for more infor-
mation on connecting these inputs.
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