20
TB MRI3-ITE(R) 12.00 E
5.3.7
Parameter switch/external
triggering of the fault recorder
By means of the parameter-change-over switches it is
possible to activate two different parameter sets.
Switching over of the parameter sets can either be
done by means of software or via the external inputs
RESET or blocking input. Alternatively, the external in-
puts can be used for Reset or blocking of the triggering
of the fault recorder.
Software-
parameter
Blocking input
used as
RESET input
used as
SET1
Blocking input
RESET input
SET2
Blocking input
RESET input
B_S2
Parameter switch RESET input
R_S2
Blocking input
Parameter
switch
B_FR
External trigger-
ing of the fault
recorder
RESET input
R_FR
Blocking input
External trigger-
ing of the fault
recorder
S2_FR
Parameter switch External trigger-
ing of the fault
recorder
With the settings SET1 or SET2 the parameter set is
activated by software. Terminals C8/D8 and D8/E8
are then available as external reset input or blocking
input.
With the setting B_S2 the blocking input (D8, E8) is
used as parameter-set change-over switch. With the
setting R_S2 the reset input (D8, E8) is used as pa-
rameter-set change-over switch. With the setting B_FR
the fault recorder is activated immediately by using the
blocking input. On the front plate the LED FR will then
light up for the duration of the recording. With the set-
ting R_FR the fault recorder is activated via the reset
input. With the setting S2_FR parameter set 2 can be
activated via the blocking input and/or the fault re-
corder via the reset input.
The relevant function is then activated by applying the
auxiliary voltage to one of the external inputs.
Important note:
When functioning as parameter change over facility,
the external input RESET is not available for resetting.
When using the external input BLOCKING the protec-
tion functions must be deactivated by software block-
ing separately (refer to chapter 5.7.1).
5.4
Protection parameters
5.4.1
Pickup value of the thermal
overload protection I
B,A
and I
B,T
For basic current I
B
, the max. permissible operating
current or optionally the rated current of the object to
be protected has to be used in either case based on
rated secondary quantities. 100% of the thermal
equivalent
ϑ
then corresponds to the max. permissible
operating temperature or optionally to the rated oper-
ating temperature.
Conversion to secondary values are to be done as per
the following formula:
I
I
n
I
B
B prim
I
N MRI
=
⋅
,
,
1
with I
B,prim
:
max. base current in A
n
I
:
c.t. ratio
I
N.MRI
:
rated current
Example:
9
,
0
A
1
1
500
A
450
I
A
1
I
;
A
1
A
500
n
;
A
450
I
B
MRI
N,
I
prim
,
B
=
⋅
=
=
=
=
5.4.2
Constant k
Constant k describes the admissible overload factor.
This factor changes the pickup value and the tripping
value of the relay.
5.4.3
Time constant
ττττ
Details on the time constants
τ
C
and
τ
W
can either be
taken from the electrical equipment’s data sheets or es-
timated on the base of practical values.
Additional influencing factors are a.o. the environ-
mental heat storing and heat conducting capacity (e.g.
mode of cable laying on the ground, in tubes or
shafts, or the additional cooling by forced convection
of transformers through fans).
5.4.4
Pickup current for phase
overcurrent element (I>)
The setting value for this parameter that appears on the
display is related to the nominal current (I
N
) of the re-
lay. This means: pickup current (Is) = displayed value x
nominal current (I
N
) e.g. displayed value = 1.25 then,
Is = 1.25 x I
N
.
