1MRK 502 001-UEN
Page 4
RARIC
Shaft current protection
The RARIC protection is built up of a test switch, terminal bases, plug-in
modules and connection parts of type COMBIFLEX. The test switch and
the terminal bases are screwed to two apparatus bars. The plug-in modules
are inserted and screwed to the terminal bases. All internal connections are
made on the rear of the terminal bases with COMBIFLEX socket leads.
Leads with a 10 A COMBIFLEX socket at one end are used for external
connections to the relay bases and leads with 20 A socket are used for con-
nections to the test switch.
Fig. 1 shows the components of the RARIC protection and the connec-
tions to the measuring and test windings of the ILDD shaft-current trans-
former. The numbers below refer to the numbering of the components in
Fig. 1.
1.
Test switch RTXP 18
When a test handle RTXH 18 is inserted into the test switch, the trip
and alarm circuits are opened. A relay test apparatus can be con-
nected to terminals 3B and 4B on the test handle to inject current into
the test winding A - B.
2.
Damping filter RXTFB 4 (only for RARIC, Version 2)
contains capacitors, reactors and resistors. One parallel resonance
and one series resonance circuit in the filter gives the frequency char-
acteristic shown in Fig. 4.
3.
Overcurrent relay RXIK1
is the measuring unit of RARIC. The operating value of RXIK 1 is
steplessly settable 0.5 - 2 mA. The current input circuit has an resist-
ance of 82 ohms and contains an RC circuit to suppress high fre-
quency disturbance signals. The output circuit contains an impulse
holding function which ensures operation also when intermittent
input current signals are received.
4.
Time relay RXKL 1
is a static relay with scale 30 ms to 99 h. The setting determines the
delay of the trip signal.
5.
Auxiliary relay RXME 18
has heavy-duty contacts which can be used in signal and tripping cir-
cuits. The relay is fitted with a red flag to indicate operation.
The flag is manually reset by means of a resetting knob in the cover.
6.
Power supply unit RXTUB 2
is an AC/DC converter which contains a transformer, full-wave recti-
fier and smoothing capacitors. The unit supplies auxiliary voltage to
the relays in RARIC.
The output DC voltage is 24 volts (± 12 V).
RARIC is also available with a DC/DC converter RXTUG 22H for
DC auxiliary voltage supply.
2 DESIGN
2.1 The RARIC protection
