Operating time characteristics for trip and reset
The operating timers’ behavior of the function can be set for trip signal and also for the release of the
function in case the pick-up element is reset before the trip time has been reached. There are three
basic operating modes available for the function. Instant operation gives the trip signal with no
additional time delay simultaneously with start signal. De nite time operation (DT) will give trip signal
with user given time delay regardless of the measured current as long as the current is above the Iset
value and thus pick-up element is active (independent time characteristics). Inverse de nite minimum
time (IDMT) will give the trip signal in time which is in relation of the set pick-up current Iset and
measured current Im (dependent time characteristics). For the IDMT operation is available IEC and
IEEE/ANSI standard characteristics as well as user settable parameters.
Uniquely to current unbalance protection there is also “Curve2” delay available which follows the
formula below:
t = Operating time
I
2meas
= Calculated negative sequence
I
N
= Nominal current
k = Constant k value (user settable delay multiplier)
I
set
= Pick-up setting of the function
Figure. 5.4.7. - 49. Operation characteristics curve for I2 > Curve2
Following table presents the setting parameters for the function time characteristics.
Table. 5.4.7. - 90. Operating time characteristics setting parameters.
Name
Range
Step
Default
Description
Delay Type
DT
IDMT
-
DT
Selection of the delay type time counter. Selection possibilities are
dependent (IDMT, Inverse De nite Minimum Time) and
independent (DT, De nite Time) characteristics.
AQ-F255
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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