Communication and the MCC mode
The phasor information from the other parallel IEDs is needed for the circular
current calculation. Therefore, horizontal GOOSE communication is needed
between IEDs when the MCC principle is used.
The transferred current phasor contains the primary value of the measured current.
The received current phasor information can be read from the input data
TRx_I_AMPL and TRx_I_ANGL for the magnitude and angle respectively. The
value "x" gives the connected parallel transformer number, a value between 1 and 3.
The sent phasor information always represents the difference between the voltage
phasor U_A and I_A. This information regarding the current phasor can be read
from the output data TR0_I_AMPL and TR0_I_ANGL. The allowed acting
operation modes for sending data are MCC or Manual, both with the input
CON_STATUS activated. The communication can be seen to be active when the
sent and received phasor magnitude is not clamped to zero. The communication
phasor magnitude found to be zero results either from a rejected acting operation
mode or too low signal magnitudes (see Voltage and current measurements
chapter). Active CON_STATUS indicates that the corresponding transformer is
connected to network and its current affects the circular current of other
transformers even when it is itself in the manual operating mode.
9.5.11 Timer characteristics
Operation timer functionality
The delay times can be set to follow either the definite time characteristic or the
inverse time characteristic with the Delay characteristic setting. By default, the
"Definite time" type is selected. The timer mode cannot be changed between cycles
T1 and T2, only either before T1 has started or after T2 has elapsed.
Table 628: Different timer mode delays
Timer mode
Setting Description
T1
Control delay time 1
First delay when the measured voltage
exceeds or falls below the limit value.
T2
Control delay time 2
Second delay when the first control did
not bring the measured voltage to a
desired level.
The delay after the command pulse activation and the restart of the timer is six
seconds. The delay is assumed to be the tap changer operating delay. The timer
status can also be read from the monitoring data TIMER_STS, where T1 active
gives a value "Lower timer1 on" or "Raise timer1 on" while T2 active gives a value
"Lower timer2 on" or "Raise timer2 on". Furthermore, the "Fast lower T on" value
indicates that the fast lowering control functionality is active (
Blocking scheme
chapter).
Activation of operation timer also activates the TIMER_ON output.
1YHT530004D05 D Section 9
Control functions
615 series 743
Technical Manual
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