16.10
SEL-400 Series Relays Instruction Manual Date Code 20171006
DNP3 Communication
DNP3 in the Relay
Binary Controls
The relay provides more than one way to control individual points within the
relay. The relay maps incoming control points either to remote bits within the
relay or to internal command bits that cause circuit breaker operations.
NOTE: The port setting DNPCL (or
DNPCL
n
for DNP3 LAN/WAN session
n) must be set to Y to enable binary
controls for the DNP3 session. Binary
Output Status requests (Object 10,
Variation 2) and Class 0 requests will
have no Binary Outputs in the
response unless DNPCL := Y.
A DNP3 technical bulletin (Control Relay Output Block Minimum Implementa-
tion 9701-002) recommends that you use one point per Object 12, control block
output relay. You can use this method to perform pulse on, latch on, and latch off
operations on selected remote bits.
If your master does not support the single-point-per-index messages or single-
operation database points, you can use the trip/close operation or use the code
field in the DNP3 message to specify operation of the points shown in Control
Point Operation on page 16.20.
Time Synchronization
The accuracy of DNP3 time synchronization is insufficient for most protection
and oscillography needs. DNP3 time synchronization provides backup time syn-
chronization in the event the relay loses primary synchronization through the
IRIG-B TIME input or some other high accuracy source.
Enable time synchronization with the TIMERQ setting (TIMERQn for DNP3
LAN/WAN Session n) and use Object 50, Variation 1, and Object 52, Variation 2
(Object 50, Variation 3 for DNP3 LAN/WAN), to set the time via a DNP3 master.
TIMERQ can be set in one of three ways:
➤ A numeric setting of 1–32767 minutes specifies the rate at which the
relay shall request a time synchronization.
➤ A setting of M disables the relay from requesting a time
synchronization, but still allows the relay to accept and apply time
synchronization messages from the master.
➤ A setting of I disables the relay from requesting a time
synchronization, and sets the relay to ignore time synchronization
messages from the master.
Effective January 1, 2008, the DNP3 standard requires that DNP3 time corre-
spond to Coordinated Universal Time (UTC). To help ease into the transition to
this standard, you can use the DNPSRC Global setting to determine whether the
relay will use local or UTC time for DNP3.
When requesting time synchronization with DNPSRC := UTC, the relay will
treat incoming DNP3 time set messages as UTC time. All DNP3 event time-
stamps (binary input changes with time, analog input changes with time, etc.)
will be in UTC time.
When requesting time synchronization with DNPSRC := LOCAL, the relay will
treat incoming time set by the DNP3 master as local time. All DNP3 event time-
stamps will be in local time.
When setting the time with local time, there is an ambiguity during the last hour
of daylight-saving time (DST) and to resolve this ambiguity, if the relay accepts a
Time Set request in this hour, it will assume the time is in DST.
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