Time Synchronization - ABB RELION 620 Series Technical Manual

1MAC504801-IB E
3.5
620 series ANSI
Technical Manual
LED indication control should never be used for tripping purposes. There
is a separate trip logic function TRPPTRC available in the relay
configuration.
LED indication control is preconfigured 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).

Time synchronization

The protection 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 protection relay is provided with a 48 hour capacitor backup that enables the real-time
clock to keep time in case of an auxiliary power failure.
The setting Synch Source determines the method to synchronize the real-time clock. If it
is 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 protection relay supports SNTP, IRIG-B, DNP3 and Modbus to update the real-time
clock. IRIG-B with GPS provides the best accuracy.
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.
Section 3
Basic functions
79