Woodward
Manual MRM3-2 GB
26
TD_MRM3-2_09.08_GB_Rev.New
5.4.16 Tripping Time or Time Factor for the Earth Fault Element (IE>+t>)
The setting procedure outlined in chapter 5.4.9 applies here as well.
5.4.17 Reset Time for the Earth Fault Element (IE>+CHAR+t>)
The setting procedure outlined in chapter 5.4.10 applies here as well.
5.4.18 Tripping Time for the CB Failure-Protection (CB+t>)
This protection is activated after a protective trip and it monitors if all phase currents have dropped
within the set time t
CBFP
to <2% x I
N
. If not, CB failure is detected and the allocated relay triggered.
(CBFP= Circuit Breaker Failure Protection).
5.4.19 External Trip (delayed)(Trip+t>)
Via the digital input A8/D8 an external trip with time delay can be activated. Trip is initiated if the
<signal existed for at least the set time. The external trip function can be allocated to a relay.
5.4.20 Trip Blocking in case of Excessive Phase Current (Trip+Block)
This function is important where power contactors are used and they are not designed to discon-
nect high short-circuit currents. In such a case no function of the MRM3-2 must initiate tripping. The
trip function is then allocated to a preceding protective element (e.g. fuse).
Trip blocking is activated as soon as the set current is exceeded. When this threshold is undershot,
all function are released again.
If the circuit breakers used are able to disconnect the short-circuit current to be expected, the func-
tion is set to EXIT.
