TB MRI3-ITE(R) 12.00 E
29
6.4.2
Example of test circuit for
MRI3-ITE
For testing
MRI3-ITE
relays only current input signals
are required. Figure 6.1 shows a simple example of a
single phase test circuit with adjustable current energiz-
ing the
MRI3-ITE
relay under test.
Figure 6.1: Test circuit
6.4.3
Checking the input circuits and
measured values
Inject a current, which is less than the relay pickup cur-
rent set values, in phase 1 (terminals B3-B4), and
check the measured current on the display by pressing
the pushbutton <SELECT/RESET>. For a relay with
rated current I
N
= 5 A, for example, a secondary cur-
rent injection of 1 A should be indicated on the dis-
play with about (0.2 x I
N
). When parameter Iprim =
„s“ is set, the indication is 0.2 x In and at „5“ the in-
dication is 1.00 [A]. The current can be also injected
into the other current input circuits (Phase 2: terminals
B5-B6, Phase 3: terminals B7-B8, Earth current: termi-
nals B1-B2) in the same manner. Compare the dis-
played current value with the reading of the ammeter.
The deviation must not exceed 33%.
General hint: When checking the individual tripping
functions, it would be advisable to release only those
parameters which shall be tested. Set parameters to
„EXIT“, since otherwise there might be tripping of sev-
eral protective functions. Attention must also be paid to
the fact that - for this protective function - the „correct“
output relay will be assigned.
Example: The tripping value of the phase overcurrent is
to be tested and the test circuit’s structure is the same
as above. In this case, in the assignment mode, relay
1 is assigned to the function t
I>
.
