Siemens 7SR242 - Current Protection: Negative Phase Sequence Overcurrent (46 NPS); Figure 3-13 Logic Diagram: Negative Phase Sequence Overcurrent (46 NPS)

7SR242 Duobias Description Of Operation
©2010 Siemens Protection Devices Limited Chapter 1 Page 33 of 52
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.
Inhibit 46IT-n
46IT-n
46IT Setting
46IT Char
46IT Time Mult
46IT Delay (DTL)
46IT-n Element
Enabled
Disabled
&
46IT Reset
Wn-IL1
Wn-IL2
Wn-IL3
NPS
>
c
46DT Setting
I2
General Pickup
c
Pickup
trip
46DT-n
46DT-n Delay
General Pickup
Inhibit 46DT-n
46DT-n Element
Enabled
Disabled
&
Figure 3-13 Logic Diagram: Negative Phase Sequence Overcurrent (46NPS)