and its current affects the circular current of other transformers even when it is
itself in the manual operating mode.
9.5.4.7
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 1014: 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 (
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:
B
U
U
d
BW
=
(
/ )
2
(Equation 191)
U
d
|U
m
– U
p
|, differential voltage
U
BW
Setting parameter
Band width voltage
t
T
B
=
−
(
)
2
1
(Equation 192)
Control functions
1MRS757644 H
1060
620 series
Technical Manual
