Common base IED values for primary current (IBase), primary voltage (V
Base) and
primary power (SBase) are set in a Global base values for settings function GBASVAL.
GlobalBaseSel: It is used to select a GBASVAL function for reference of base values.
16.6.3.1 Current reversal
M13933-6 v5
The current reversal function is set on or off by setting the parameter CurrRev to
Enabled or Disabled. Time delays shall be set for the timers tPickUpRev and
tDelayRev.
tPickUpRev is chosen shorter (<80%) than the breaker opening time, but minimum 20
ms.
tDelayRev is chosen at a minimum to the sum of protection reset time and the
communication reset time. A minimum tDelayRev setting of 40 ms is recommended.
The reset time of the directional residual overcurrent protection (EF4PTOC) is
typically 25 ms. If other type of residual overcurrent protection is used in the remote
line end, its reset time should be used.
The signal propagation time is in the range 3 – 10 ms/km for most types of
communication media. In communication networks small additional time delays are
added in multiplexers and repeaters. Theses delays are less than 1 ms per process. It is
often stated that the total propagation time is less than 5 ms.
When a signal picks-up or drops out there is a decision time to be added. This decision
time is highly dependent on the interface between communication and protection used.
In many cases an external interface (teleprotection equipment) is used. This equipment
makes a decision and gives a binary signal to the protection device. In case of analog
teleprotection equipment typical decision time is in the range 10 – 30 ms. For digital
teleprotection equipment this time is in the range 2 – 10 ms.
If the teleprotection equipment is integrated in the protection IED the decision time can
be slightly reduced.
The principle time sequence of signaling at current reversal is shown.
Section 16 1MRK 504 163-UUS A
Scheme communication
836 Transformer protection RET670 2.2 ANSI
Application manual
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