ABB RELION REX640, Техническое руководство, Страница: 491 / 1960

directionality of the oversusceptance and overconductance criteria can be defined
as forward, reverse or non-directional, and the boundary lines can be tilted if
required by the application. This allows the optimization of the shape of the
admittance characteristics for any given application.
EFPADM supports two calculation algorithms for admittance. The admittance
calculation can be set to include or exclude the prefault zero-sequence values of
Io and Uo. Furthermore, the calculated admittance is recorded at the time of the trip
and it can be monitored for post-fault analysis purposes.
To ensure the security of the protection, the admittance calculation is supervised
by a residual overvoltage condition which releases the admittance protection during
a fault condition. Alternatively, the release signal can be provided by an external
binary signal.
The function contains a blocking functionality. It is possible to block function
outputs, timers or the function itself.
4.2.4.4 Analog channel configuration
EFPADM has two analog group inputs which must be properly configured.
Table 564: Analog inputs
Input Description
IRES Residual current (measured or calculated)
URES Residual voltage (measured or calculated)
See the preprocessing function blocks in this document for the possible
signal sources.
There are a few special conditions which must be noted with the configuration.
Table 565: Special conditions
Condition Description
URES calculated The function requires that all three voltage
channels are connected. Setting
VT connec-
tion
must be "Wye" in that particular UTVTR..
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.2.4.5 Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of EFPADM can be described using a module diagram. All the
modules in the diagram are explained in the next sections.
1MRS759142 F Protection functions
REX640
Technical Manual
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