Manual MRM3-2 GB
Woodward
TD_MRM3-2_09.08_GB_Rev.New
23
5.4.5 t2x and t6x Minimal Trip Time During the Starting Process.
With this parameter the fastest trip time during the start-up phase is limited for the thermal image. If
the selected pick-up value k x I
B
is exceeded by two times or six times, the characteristic breaks to
definite time. This prevents that a higher start current causes the thermal image to overflow at the
first instant. Normally six times the value is selected. If not desired, the characteristic can be oper-
ated without breaking by setting EXIT.
5.4.6 Phase Undercurrent Element (I<)
Running-dry protection/V-belt split
The MRM3-2 trips if after a successful start the current lies below the adjusted current threshold for
a definite time. Undercurrent is only active during mode RUNNING. The undercurrent element is
also blocked if the measured current lies below the STOP threshold (see chapter 4.1). EXIT is set,
then this element is switched off.
The time delay for the undercurrent element is set to seconds.
Note:
The time delay must not be set shorter than the STOP time, otherwise every time the motor is
stopped, an undercurrent trip occurs.
5.4.7 Phase Over current Element (I>)
When adjusting the pick-up value for the phase over-current element I>, an indicating value, refer-
ring to the secondary rated current I
N
, is displayed. This element is only active during mode
RUNNING.
5.4.8 Trip Characteristics for the Phase Over current Element (I>+CHAR)
There are the following standard trip time characteristics available (see 7.4.6:
DEFT -
Definite Time (definite time
over
current
protection)
NINV -
Normal
inverse
VINV -
Very
inverse
EINV -
Extremely
inverse
RINV -
RI-Inverse
LINV -
Long term Inverse
