measurements. If this factor is less than 1, it implies that the source on MV side is
comparatively weak and hence forward regulation will be carried out. Here, if
LDC
enable
is set as TRUE, then
Rv pwr flow allowed
must be internally set as TRUE if not
already so.
If PRF > 1, it implies that the source on MV side is stronger and then HV side
regulation will take place. It should be noted that in HV side regulation, increasing
the HV winding turns will increase the HV side voltage and vice versa. The
commands issued will be opposite of that issued for forward regulation. The output
REV_REG is activated during HV side regulation, which can be used to select the
setting group which gives the line parameters on HV side for LDC.
If
Regulation mode
is set as “Auto select”, measurements from both HV
and MV side should be available for the accuracy of PRF calculation.
9.10.5.8 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" mode 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 1573: 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 (
Chapter 9.10.5.10 Blocking
scheme
).
Activation of operation timer also activates the TIMER_ON output.
IDMT type operation
The IDMT timer can be selected by setting
Delay characteristic
to "Inverse time". The
minimum time at the inverse time characteristic is limited to 1.0 second. However,
the minimum recommended setting of the control delay times T1 and T2 is 10
seconds when the definite time delay is used and 25 seconds when the inverse time
delay is used.
The inverse time function is defined by the equations:
Control functions
1MRS759142 F
1714 REX640
Technical Manual
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