The parameter
DefDirMode determines the response at the end of the definitive time. It can be
set to be either directional (in tripping direction) or non-directional.
There is still a definitive zone even using the overcurrent starter (OC), but only
with respect to the parameters
Delay (Def) and DefDirMode.
5.1.6.5
Backup overcurrent unit (O/C Backup Protection)
GUID-20B5299D-4AF0-474F-A39C-5B2CEC91FFB8 v1
The settings for the backup overcurrent unit are made via the sub-menu O/C BACKUP
PROTECTION. The setting of the parameter
I O/C determines the pick-up level, which can be
chosen in steps of 0.1 I
N
between 0 and 10 I
N
. The associated time delay is set in steps of 0.1 s
between 0 and 10 s by means of the parameter
Delay O/C.
The pick-up signal of the overcurrent unit is also used by the STUB protection. If the function is
being used for this purpose, that is, the binary I/P Isol open is at logical 1, the tripping time is
fixed at 25 ms.
5.1.6.6
VT supervision
GUID-251A8D53-AFE5-46E8-A370-18F24C8A0401 v1
The parameters for setting the VT supervision function are located in the sub-menu VT
SUPERVISON. One of four different operating modes can be selected by using VTSupMode.
The function processes zero and negative-sequence components, which are either used on
their own (ZeroSeq and NegSeq) or combined (Zero×NegSeq and Spec).
ZeroSeq
0
0
U
I
NegSeq
2
2
U
I
Zero×NegSeq
0
0
2
2
U
I
U
I
Spec
2
0
2
U
I
I
The four pick-up values are the settings of the parameters
U0min VTSup, U2min VTSup, I0min
VTSup and I2min VTSup. They can be set between 0 and 2 UN (or IN) in steps of 0.01. The basic
settings are 0.2 U
N
for the voltage and 0.07 I
N
for the current.
Only the NegSeq or Spec options are available in ungrounded systems.
Upon operating, the VT supervision function is normally required to immediately block the
distance protection function. Provision is made, however, for blocking the distance function
after a delay of 12 s by setting the parameter
VTSupBlkDel. This parameter is normally set in
cases where only the overcurrent starters are in use.
If the VT supervision function remains picked up for longer than 12 s, it resets only after a delay
(1 s). Should a fault give rise to zero or negative-sequence current components, it resets
immediately.
Section 5
1MRK 505 406-UEN B
Bay protection functions
48
Bay protection functions REB500
Technical manual
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