Sel SEL-421 - Relay Test Connections

U.6.9
Date Code 20020501 User’s Guide SEL-421/SEL-421-1 Relay
Testing and Troubleshooting
Relay Test Connections
Relay Test Connections
NOTE: The procedures specified in
this subsection are for initial relay
testing only. Follow your company
policy for connecting the relay to the
power system.
The SEL-421 Relay is a flexible tool that you can use to implement many
protection and control schemes. Although you can connect the relay to the
power system in many ways, connecting basic bench test sources helps you
model and understand more complex relay field connection schemes.
Test Setup
Test Source Connections
For each relay element test, you must apply ac voltage and current signals to
the relay. The text and figures in this subsection describe the test source
connections you need for relay protection element checks. You can use these
connections to test protective elements and simulate all fault types.
Connections for Three Voltage Sources and Three Current Sources
Figure 6.2 shows the connections to use when you have three voltage sources
and three current sources available.
Figure 6.2 Test Connections Using Three Voltage and Three Current
Sources.
Three-Phase
Voltage and Current
Test Sources
IA
VB
IB
VC
IC
VA
IAW
Z01 Z02 Z03 Z04 Z05 Z06
Z13 Z14 Z15 Z16 Z17 Z18
IBW ICW
VAY VBY VCY
Relay Rear-Panel Analog
Voltage and Current Inputs