Timer
Once activated, Timer activates the START output. Depending on the value of
the
Operating curve type
setting, the time characteristics are according to DT or
wattmetric IDMT. When the operation timer has reached the value of
Operate delay
time
in the DT mode or the maximum value defined by the inverse time curve,
the OPERATE output is activated. If a drop-off situation happens, that is, a fault
suddenly disappears before the operating delay is exceeded, the timer reset state is
activated. The reset time is identical for both DT or wattmeter IDMT. The reset time
depends on the
Reset delay time
setting.
Timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is
available in the monitored data view.
Blocking logic
There are three operation modes in the blocking function. The operation modes
are controlled by the BLOCK input and the global setting in Configuration>
System> Blocking mode which selects the blocking mode. The BLOCK input can
be controlled by a binary input, a horizontal communication input or an internal
signal of the protection relay's program. The influence of the BLOCK signal activation
is preselected with the global setting
Blocking mode
.
The
Blocking mode
setting has three blocking methods. In the "Freeze timers"
mode, the operation timer is frozen to the prevailing value, but the OPERATE output
is not deactivated when blocking is activated. In the "Block all" mode, the whole
function is blocked and the timers are reset. In the
Block OPERATE output
mode, the
function operates normally but the OPERATE output is not activated.
4.2.7.6 Timer characteristics
In the wattmetric IDMT mode, the OPERATE output is activated based on the timer
characteristics:
(Equation 76)
t[s] operation time in seconds
k set value of
Time multiplier
P
ref
set value of
Reference power
P
cal
calculated residual power
1MRS759142 F Protection functions
REX640
Technical Manual
535
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