Chapter 1) 7SR242 Duobias Description Of Operation
©2015 Siemens Protection Devices Limited
Chapter 1 Page 36 of 60
3.7
Current Protection: Negative Phase Sequence
Overcurrent (46NPS)
Optionally four NPS current elements are provided – 2 x 46IT and 2 x 46DT. Each element can be selected to
either winding 1 or winding 2.
The 46IT elements can be configured to be either definite time lag (DTL) or inverse definite minimum time (IDMT),
46IT Setting
sets the pick-up current level for the element.
A number of shaped characteristics are provided. An inverse definite minimum time (IDMT) characteristic is
selected from IEC and ANSI curves using
46IT Char
. A time multiplier is applied to the characteristic curves using
the
46IT Time Mult
setting. Alternatively, a definite time lag delay (DTL) can be chosen using
46ITChar
. When
Delay (DTL) is selected the time multiplier is not applied and the
46IT Delay (DTL)
setting is used instead.
The
46IT Reset
setting can apply a,
definite time delayed
or
ANSI (DECAYING)
reset.
The 46DT elements have a DTL characteristic.
46DT Setting
sets the pick-up current and
46DT Delay
the
follower time delay.
Operation of the negative phase sequence overcurrent elements can be inhibited from:
Inhibit 46IT
A binary or virtual input.
Inhibit 46DT
A binary or virtual input.
User Inhibit
Reylogic (graphical logic).
Figure 3-13 Logic Diagram: Negative Phase Sequence Overcurrent (46NPS)
Summary of Contents for 7SR242 Duobias
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