4
TD_MRI1-IU_05.04_GB
3 Design
3.1 Connections
Figure 3.1:
Connection diagram
3.1.1
Analogue input circuits
The protection unit receives the analogue input signals
of the phase currents IL1 (B3-B4), IL2 (B5-B6), IL3 B7-
B8)), as well as the phase voltages via isolated input
transformers in V-connection.
The constantly detected current measuring values are
galvanically decoupled, filtered and finally fed to the
analogue/digital converter.
3.1.2
Output relays
The
MRI1-IU
has five output relays. Two output relays
with two change-over contacts and two with one
change-over contacts can be assigned as required.
All relays are working current relays, only the relay for
self supervision is an idle current relay. To prevent that
the C.B. trip coil circuit is interrupted by the
MRI1-IU
first, i.e. before interruption by the C.B. auxiliary con-
tact, a dwell time is fixed.
This setting ensures that the
MRI1-IU
remains in self
holding for 200ms after the fault current is interrupted.
3.1.3
Blocking input
The blocking functions adjusted before will be blocked
if an auxiliary voltage is connected to (terminals)
D8/E8. (Refer to chapter 5.2.10)
3.1.4
External reset input
Please refer to chapter 5.4.
Summary of Contents for HighTECH Line MRI1IU
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