Section 3 1MAC309294-MB F
Basic functions
50 RER620
Technical Manual
3.3 LED indication control
The relay includes a global conditioning function LEDPTRC that is used with the
protection indication LEDs.
LED indication control is pre configured in a such way that all the protection functions
general pickup and trip signals are combined with this function (available as output signals
OUT_PICKUP and OUT_TRIP). These signals are always internally connected to Pickup
and Trip LEDs. LEDPTRC collects and combines phase information from different
protection functions (available as output signals OUT_PU_A /_B /_C and OUT_TRP_A
/_B /_C). There is also combined ground fault information collected from all the ground
fault functions available in the relay configuration (available as output signals
OUT_PU_NEUT and OUT_TRP_NEUT).
3.4 Time synchronization
The relay has an internal real-time clock which can be either free-running or synchronized
from an external source. The real-time clock is used for time stamping events, recorded
data and disturbance recordings.
The relay is provided with a 48-hour capacitor back-up that enables the real-time clock to
keep time in case of an auxiliary power failure.
Setting Synch Source determines the method how the real-time clock is synchronized. If
set to “None”, the clock is free-running and the settings Date and Time can be used to set
the time manually. Other setting values activate a communication protocol that provides
the time synchronization. Only one synchronization method can be active at a time but
SNTP provides time master redundancy.
The relay supports SNTP, IRIG-B, DNP3 and Modbus to update the real-time clock.
IRIG-B with GPS provides the best accuracy.
LED indication control should never be used for tripping purposes. There
is a separate trip logic function TRPPTRC available in the relay
configuration.
When Modbus TCP or DNP3 over TCP/IP is used, SNTP time
synchronization should be used for better synchronization accuracy.
DNP3 can be used as a time synchronization source.
When the SNTP server IP setting is changed, the relay must be rebooted to
activate the new IP address. The SNTP server IP settings are normally
defined in the engineering phase via the SCL file.
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