Schweitzer Engineering Laboratories SEL-421-4 - Figure 3.6 Test Connections Using a Single Current Source for a Phase-To-Phase Fault; Checking Relay Operation

3.8
SEL-421 Relay Instruction Manual Date Code 20171021
Testing
Checking Relay Operation
Checking Relay Operation
The SEL-421 comes to you with all functions fully checked and calibrated so that
the relay operates correctly and accurately. You can perform tests on the relay to
verify proper relay operation, but you do not need to test every relay element,
timer, and function in this evaluation. The following checks are valuable for con-
firming proper SEL-421 connections and operation:
➤ AC connection check (metering)
➤ Commissioning tests
➤ Functional tests
➤ Element verification
An ac connection check uses relay metering to verify that the relay current and
voltage inputs are the proper magnitude and phase rotation (see Examining
Metering Quantities on page 3.35 in the SEL-400 Series Relays Instruction Man-
ual).
Commissioning tests help you verify that you have properly connected the relay
to the power system and all auxiliary equipment. These tests confirm proper con-
nection of control inputs and control outputs as well (see Operating the Relay
Inputs and Outputs on page 3.61 in the SEL-400 Series Relays Instruction Man-
ual).
Figure 3.6 Test Connections Using a Single Current Source for a Phase-to-
Phase Fault
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 Secondary
Voltage and Current Inputs
N
N
N