6
TB MRI3-ITE(R) 12.00 E
Voltage measuring for the directional detection:
Figure 3.4: Measuring of the phase voltages for the directional
detection at earth-fault protection (I
E>
and I
E>>
).
3.1.1
Analog input circuits
The protection unit receives the analog input signals of
the phase currents IL1 (B3-B4), IL2 (B5-B6), IL3 (B7-B8)
and the residual current I
E
(B1-B2) each via separate
input transformers.
The constantly detected current measuring values are
galvanically decoupled, filtered and finally fed to the
analog/digital converter.
3.1.2
Output relays
Two relays are equipped with two change-over con-
tacts and three relays with each one change-over con-
tact for alarm. Apart from the relay for self-supervision,
all protective functions can be optionally assigned:
•
Relay 1: C1, D1, E1 and C2, D2, E2
•
Relay 2: C3, D3, E3 and C4, D4, E4
•
Relay 3: C5, D5, E5
•
Relay 4: C6, D6, E6
•
Relay 5: Self-supervision C7, D7, E7
All trip and alarm relays are working current relays, the
relay for self supervision is an idle current relay.
3.2
Relay output contacts
Figure 3.5: Relay outputs
3.2.1
Blocking input
The function for blocking can be parameterized arbi-
trary. When an auxiliary voltage is connected to
D8/E8 those relay functions will be blocked which
were parameterized before (see chapter 5.7.1).
3.2.2
External reset input
See chapter 5.9
