Siemens 6MD85, Manual

Page: 652 / 1256

With the
Min. time of the curve
parameter, you define a minimum operate delay time. The operate
delay time of inverse-time characteristic curve never falls below the minimum operate delay time. If the
setting is left on its default value of 0 s, this parameter has no effect on the inverse-time characteristic curve.
This parameter is only required for time coordination in recloser schemes. For all other applications, Siemens
recommends keeping the default setting of 0 s.
i
i
NOTE
If the set value is smaller than the smallest possible time delay of the inverse-time characteristic curve, the
parameter has no influence on the delay time.
Parameter:
Additional time delay
•
Recommended setting value
(_:781:115) Additional time delay
=
0.00 s
With the
Additional time delay
parameter, you define a definite-time delay in addition to the inverse-
time delay.
If the setting is left on its default value of 0 s, this parameter has no effect on the inverse-time characteristic
curve.
This parameter is only required for time coordination in recloser schemes. For all other applications, Siemens
recommend keeping the default setting of 0 s.
Parameter:
Threshold
•
Default setting
(_:781:3) Threshold
=
1.20 A
The setting depends on the minimal occurring ground-fault current. This must be determined.
Parameter:
Time dial
•
Default setting
(_:781:101) Time dial
=
1
With the
Time dial
parameter, you displace the characteristic curve in the time direction.
The set value for the
Time dial
parameter is derived from the time-grading schedule that has been prepared
for the electrical power system. Where overcurrent protection is used in emergency mode, shorter time delays
might be reasonable (one grading time above fast tripping), since the emergency mode only operates if the
main protection function fails.
Where no time grading and therefore no displacement of the characteristic curve is required, leave the
Time
dial
parameter at
1
.
Parameter:
Reset
•
Default setting
(_:781:109) Reset
=
disk emulation
With the
Reset
parameter, you define whether the stage drops out according to the dropout characteristic
curve (in accordance with the behavior of a disk emulation = rotor disk) or instantaneously.
Parameter Value Description
disk emulation
Select this setting if the device is coordinated with electromechanical
devices or other devices which perform a dropout after a disk emulation.
instantaneous
Select this setting if the dropout is not to be performed after disk emulation
and an instantaneous dropout is desired instead.
Settings
Addr. Parameter C Setting Options Default Setting
General
_:2311:101 General:Emergency
mode
•
no
•
caused by main prot.
•
caused by binary input
no
7.5.5.3
Protection and Automation Functions
7.5 Overcurrent Protection, Ground
652 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017