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8 TD_MRI1-IU_05.04_GB
5.2 Setting procedure
After push button <SELECT/RESET> has been pressed,
always the next measuring value is indicated. Firstly
the operating measuring values are indicated and then
the setting parameters. By pressing the <ENTER> push
button the setting values can directly be called up and
changed.
5.2.1 Current setting values for
overcurrent relay (I
SN
und I
SL
)
When adjusting the setting values I
SN
(during normal
operation) and ISL (during undervoltage) the values
shown on the display are related to the nominal cur-
rent I
N
.
This means:
Pickup current (I
SN
) = displayed value x rated current
(I
N
)
e.g. if displayed value = 1.25, then Is = 1.25 x IN.
The pickup of the relay is indicated by the flashing LED
I>. LED U flashes red.
The pickup value ISL is also indicated by the flashing
LED I>. LED U however flashes red.
5.2.2 Time current characteristics for
phase overcurrent element
(CHAR I>)
By setting this parameter, one of the following
4 messages appears on the display:
DEFT - Definite Time
NINV - Normal Inverse
VINV - Very Inverse
EINV -
Extremely Inverse
Anyone of these four characteristics can be chosen by
using <+> <->-push buttons, and can be stored by us-
ing <ENTER>-push button.
5.2.3 Trip delay or time multiplier for
phase overcurrent element (t
I>
)
Usually, after the characteristic is changed, the time
delay or the time multiplier should be changed accord-
ingly. In order to avoid an unsuitable arrangement of
relay modes due to carelessness of the operator, the
following precautions are taken:
After the characteristic setting, the setting process turns
to the time delay setting automatically. The LED tI> is
going to flash yellow to remind the operator to change
the time delay setting accordingly. After pressing the
<SELECT>-push button, the present time delay setting
value is shown on the display. The new setting value
can then be changed by using <+> <-> -push buttons.
If, through a new setting, another relay characteristic
other than the old one has been chosen (e.g. from
DEFT to NINV), but the time delay setting has not been
changed despite the warning from the flashing LED,
the relay will be set to the most sensitive time setting
value of the selected characteristics after five minutes
warning of flashing LED tI>. The most sensitive time set-
ting value means the fastest tripping for the selected re-
lay characteristic.