Date Code 20010518 General Description 2-3
SEL-2020 Instruction Manual
Auto-Configuration
Setting the SEL-2020 communication parameters for a port is simplified through the SEL-2020’s
auto-configuration process. This process determines the proper baud to communicate with the
connected device. The SEL-2020 also determines the startup string, relay type, Fast Meter
capability, and relay ID for any SEL relay connected to its port. You should use the SET P
command to activate and configure each port that has a connected device.
SYNCHRONIZING TIME SOURCE
You can synchronize the attached devices to an external time source or to the SEL-2020 built-in
battery-backed clock.
Accepts External IRIG-B Input
The SEL-2020 accepts a modulated or demodulated IRIG-B signal through a rear-panel BNC
connector. Three internal jumper settings are required to identify which type of signal,
modulated or demodulated, will be applied to the SEL-2020. An internal database element
asserts when the SEL-2020 receives an IRIG-B signal.
Generates IRIG-B Internally
If no external IRIG-B signal is applied, the SEL-2020 internal clock/calendar generates an IRIG-
B signal. The SEL-2020 includes an internal battery-backed clock/calendar that maintains
correct time with or without external power. The lithium-type battery has an expected life of ten
years. The internal clock is accurate to within 1 minute per year with power applied. You can
easily reset the clock and calendar using the SEL-2020 TIME and DATE commands.
Distributes IRIG-B through Ports 1-16
The SEL-2020 distributes a demodulated IRIG-B signal through all of its 16 rear ports. You can
use this to synchronize any type of device, such as a relay, fault recorder, or meter, that can
decode the IRIG-B signal. To use this feature, you need only to connect the device to the desired
SEL-2020 port using a special cable designed for both communication and IRIG-B signal. For
devices that do not have an IRIG-B port or cannot decode the IRIG-B signal, the SEL-2020 can
send time and date messages on a periodic or time basis to keep their clocks synchronized.
COMMUNICATIONS PROCESSOR
The SEL-2020 has a distinct and significant advantage over simple port switches because of its
sophisticated and powerful communication processing capabilities.
Send Messages Triggered by SEL
OGIC Control Equations
Messages sent from the SEL-2020 can be used to request data from other devices, or to control
other devices. Use “20” messages, such as 20METER and 20TARGET, to request SEL relay
data that are recognized by the SEL-2020 and are automatically parsed upon arrival. Use non
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