Woodward HighPROtec MCDLV4, Руководство пользователя

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Protective Elements
Id
–
Phase Current Differential Protection [87L, 87T]
Available elements:
Id
General Description of the Line Differential Protection Principle
The line differential protection is based on two protection devices that are supervising the phase currents at either
end of a line and communicating with each other via a dedicated ProtCom protection communication interface.
The permanent availability and quality of the ProtCom connection is crucial for the line differential protection.
Therefore the connection is supervised continuously. Whenever the ProtCom is found to be not o.k., the line
differential protection (in particular the “Id” module described here) is immediately blocked until the connection gets
re-established. Since the idea of phase current differential protection consists in two devices working as a “pair” the
phase current differential protection is always blocked on both sides as soon as either side is blocked via e. g. an
external blocking.
The protective device provides restrained phase differential protection function with user-configurable multiple slope
percentage restrained characteristic that allows to compensate for both the static error and the dynamic error. The
static error accounts for transformer static magnetizing current and current measurement circuit calibration errors.
The dynamic error may be caused by Tap Changing (OLTC) and by CT saturation caused by heavy fault currents.
In addition, the static tripping characteristic can be modified temporarily at the user’s choice to prevent some
nuisance tripping from the harmonic inrush during energization, over-excitation, or deep CT saturation. The
harmonic inrush is evaluated through 2
nd
, 4
th
harmonics.
597 MCDLV4 DOK-HB-MCDLV4-2E
In Zone Transformer (free option)
MCD LV4
MCD LV 4
Fiber Optic (System Communication )
SCADA
MCD L V4
Cable or Overhead Line
USB
Parameter Setting
Transfer Signals
Transfer Trips
Remote Access Option
(local and remote )
(local)
(up to 24 km depending on quality of FO)
Id
_Z
01
All via FO cable (Protection Communication)