Application And Setting Notes - Siemens 6MD85 Manual

contacts. The subfunction for detecting a 3-phase measuring-voltage failure (see chapter
Measuring-Voltage Failure
This subfunction can be switched on or off separately using the Switch-on 3ph. failure parameter.
8.3.2.6

Application and Setting Notes

Parameter: Asym.fail. - time delay
•
Recommended setting value (_:113) Asym.fail. - time delay = 10.00 s
The Asym.fail. - time delay parameter allows you to set the time during which a system incident
detected after the occurrence of the unbalance resets the monitoring. This setting is important in the case of
weak infeed (current < 10 % of rated current) in order to give certain protection functions (such as distance
protection) more time for detecting system incidents. As long as the time delay runs, it is assumed that the
unbalance is due to a system incident.
As soon as the time has elapsed, the supervision assumes a measuring-voltage failure and seals in.
Siemens recommends using the default setting.
If you want the seal-in function to operate sooner or at once, you can reduce the time.
Parameter: Asym.fail.-DO on netw.flt.
•
Recommended setting value (_:115) Asym.fail.-DO on netw.flt. = No
Parameter Value
no
yes
Parameter: 3ph.fail. - VA,VB,VC <
•
Recommended setting value (_:101) 3ph.fail. - VA,VB,VC < = 5 V
The 3ph.fail. - VA,VB,VC < parameter allows you to set the pickup value of the monitoring.
Siemens recommends using the default setting.
If you expect major disturbances acting upon the voltage inputs, you can increase this value. Increasing the
values makes the supervision more sensitive to 3-phase system incidents.
Parameter: 3ph.fail. - phs.curr.release
•
Recommended setting value (_:102) 3ph.fail. - phs.curr.release = 0.1 A for I
0.5 A for I
The 3ph.fail. - phs.curr.release parameter is used to define the phase current threshold above
which the monitoring is released.
Siemens recommends using the default setting.
Parameter: 3ph.fail. - phs.curr. jump
•
Recommended setting value (_:103) 3ph.fail. - phs.curr. jump = 0.1 A for I
0.5 A for I
SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
) is not released in this situation, for example, because the current flow is too low.
Description
After elapse of the time delay the supervision function seals in. Even if the
system incident criterion is fulfilled, the protection functions concerned will
remain blocked.
This avoids an unselective tripping of the protection functions due to an
absence of the measuring voltage in the case of an unbalanced system inci-
dent.
This is the default setting.
The seal-in function is switched off. The supervision drops out immediately
when a system incident is detected. With this setting, the unbalanced meas-
uring-voltage failure is only reported, and in the event of a double failure
(measuring-voltage failure and system incident in parallel), unselective trip-
ping is preferred.
= 5 A
rated
= 5 A
rated
Supervision Functions
8.3 Supervision of the Secondary System
8.3.2.4 3-Phase
rated
= 1 A or
rated
= 1 A or
943