Woodward
Manual MRN3 GB
34
TD_MRN3_09.08_GB_Rev.New
5.8.3 Unit of the measuring values displayed
The measuring values can optionally be shown in the display as a multiple of the "sec" rated value
(x ln) or as primary current (A). According to this the units of the display change as follows:
Indication as
Range
Unit
sec. voltage
000V – 999V
V
primary voltage
.000 – 999V
1K00 – 9K99
10K0 – 99K9
100K – 999K
1M00 – 3M00
V
KV
KV
KV
MV
Table 5.5: Units of the display
5.8.4 Indication of fault data
All faults detected by the relay are indicated on the front plate optically. For this purpose, the four
LEDs (L1, L2, L3, f) and the four function LEDs (U<, U<<, U>, U>>, f1, f2, f3,
ΔΘ
und df/dt) are
equipped at MRN3. Not only fault messages are transmitted, the display also indicates the tripped
protection function. If, for example an over current occurs, first the respective phase LED will light
up. LED I> lights up at the same time. After tripping the LEDs are lit permanently.
5.9 Fault
memory
When the relay is energized or is energized or trips, all fault data and times are stored in a non-
volatile memory manner. The MRN3 is provided with a fault value recorder for max. five fault occur-
rences. In the event of additional trippings always the oldest data set is written over.
For fault indication not only the trip values are re-corded but also the status of LEDs. Fault values
are indicated when push buttons <-> or <+> are pressed during normal measuring value indication.
•
Normal measuring values are selected by pressing the <SELECT/RESET> button.
•
When then the <-> button is pressed, the latest fault data set is shown. By repeated
pressing the <-> button the last but one fault data set is shown etc. For indication of fault
data sets abbreviations FLT1, FLT2, FLT3, ... are displayed (FLT1 means the latest fault
data set recorded). At the same time the parameter set active at the occurrence is shown.
•
By pressing <SELECT/RESET> the fault measuring values can be scrolled.
•
By pressing <+> it can be scrolled back to a more recent fault data set. At first FLT5, FLT4,
are always displayed. When fault recording is indicated (FLT1 etc), the LEDs flash in
compliance with the stored trip information, i.e. those LEDs which showed a continuous
light when the fault occurred are now blinking blinking to indicate that it is not a current
fault. LEDs which were blinking blinking during trip conditions, (element had picked up) just
briefly
flash.
•
If the relay is still in trip condition and not yet reset (TRIP is still displayed), no measuring
values can be shown.
•
To delete the trip store, the push button combination <SELECT/RESET> and <->, has to
be pressed for about 3s. The display shows “wait”.
