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VMD460-NA_D00001_05_M_XXEN/01.2020
3. Functional description
The VMD460-NA is intended for protecting the network and the (generating) plant from
inadmissible operating states and for causing a disconnection. For this purpose, the
VMD460-NA is designed according to the principles of single-fault tolerance. This oc-
curs as soon as at least one of the activated protective or monitoring functions trips.
If the (re-)connection conditions are fulfilled, the VMD460-NA enables the coupling of
the generating plant to the network.
Details are regulated by the applicable (application) standard and guideline.
•
Which protective and monitoring functions are used or are active/inactive.
•
How the protective and monitoring functions are parameterised in detail.
•
Further details regarding calculation methods and device behaviour
•
Whether the (re-)connection takes place automatically or after manual acknowledge-
ment.
The country-specific (application) standards and guidelines are stored in the device as
selectable basic programs.
3.1 Measurement functions
3.1.1
Monitoring of different system types:
1AC, 3AC, 3NAC
The VMD460-NA is able to monitor different system types (1AC, 3AC, 3NAC). The system
type is defined via the "Coupling" parameter.
In addition, the nominal system voltage is set via the "U
(L-N)
/U
(L-L)
" parameter.
3.1.2
Continuous monitoring of the phase voltage and line-to-line voltage
The VMD460-NA continuously measures the available phase voltages and line-to-line
voltages as well as the power frequency. It also calculates the measured quantities rel-
evant for the protective and monitoring functions.
