Date Code 20010518 “Job Done” Examples - (Example 9) 4-67
SEL-2020 Instruction Manual
EXAMPLE 9: SEL-2020 APPLIED TO SCADA RTU CONTROL
I
NTRODUCTION
Example 9 is similar to the previous examples, but we add the capability to open and close
breakers by commanding the SEL-251 relays through the SCADA system.
IDENTIFYING THE PROBLEM
Your objective in this example is to be able to rapidly open and close breakers via SCADA RTU
command.
DEFINING THE SOLUTION
The solution is to use the built-in operate support of the SEL-2020. To get the best response
from the relay, we will use SEL-251-1 relays because they support Fast Operate commands.
Fast Operate commands are short binary commands that cause the SEL-251-1 to open or close
within 16 milliseconds of receiving the message. If we used conventional SEL-251 relays, the
SEL-2020 would have to issue ASCII OPEN and CLOSE commands, which can take many
seconds to function.
The following steps will have to be taken:
1. Make sure Fast Operate commands are enabled in the SEL-251.
2. Enable operate control of the SEL-251 relays using the SET A command on each SEL-251
port.
3. Establish SEL
OGIC for opening and closing using SET L on each SEL-251 port.
4. Verify connection by sending various operate commands to relays.
SET THE SEL-2020 STEP-BY-STEP
Verify that the operate jumper on the relay is in the operate enable position. On some relays,
such as the SEL-321-1, you will also need to confirm that the Fast Operate enable setting is set
to yes.
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