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2.37.8 Communication test
(i) Local test (Local-test)
When setting [Local-test]=On, ‘1’ is set for Local test bit of SCOM4 frame so that zero-ampere
control is executed at the remote end. The zero-ampere control is the one of test functions that
a local IED can treat the remote current data as zero.
SCOM1
MS0
RA0
MS0
RA3
MS0
Spare
MS0
RA0
MS0
RA3
MS0
Spare
SCOM2
MS1
RA1
MS1
RA4
MS1
Spare
MS1
RA1
MS1
RA4
MS1
Spare
SCOM3
MS2
RA2
MS2
RA5
MS2
Spare
MS2
RA2
MS2
RA5
MS2
Spare
SA0
SA1
SA2
SA3
SA4
SA5
SA6
SA7
SA8
SA9
SA10
SA11
Figure 2.37-7 Location of local test bit
For example, during the test, suppose that setting [Local-test]=Off (as a default condition);
and CB and DSs are open at the local end. Remote CB can be tripped by the remote IED, if
currents are injected at the local IED while the communication is established between IEDs.
That is, the user needs to set [Local-test]=On for the test. Note that Test LED is lit while the
setting is On.
(ii) Local loop test (Loop-test)
Suppose that GRL200s at local and remote ends are connected with TX and RX fiber optical
cables. If setting [Loop-test]=On, the user can have loop-back test at the local IED by disabling
sampling synchronization supervision function. Note other supervision functions are not
disabled, but there are following limitations during the test.
➢ Sensitivity of DIF and DIFG elements becomes double. (If the injection of test current at
one terminal is 1A, the differential current Id becomes 2A.)
➢ “Test LED” is On (“In service LED” is Off.)
(iii) Open test (OPEN 1/OPEN 2)
If communication channels between IEDs should not be connected for testing, the user can cut
the channel when On is set setting [OPEN *]. For example, when setting [OPEN 1]=On, the
communication channel#1 will be cut at the local end. The default setting is Off.
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