7SR11 & 7SR12 Description Of Operation
Chapter 1 Page 56 of 88 ©2017 Siemens Protection Devices Limited
It should be noted that neutral voltage displacement can only be applied to VT arrangements that allow zero
sequence flux to flow in the core i.e. a 5-limb VT or 3 single phase VTs. The VT primary winding neutral must be
earthed to allow the flow of zero sequence current.
Inhibit 59IT
59NIT
59NIT Setting
59NIT Charact
59NIT Time Mult
59NIT Delay (DTL)
59NIT Element
Enabled
Disabled
59NIT Reset
VL1
VL2
VL3
ZPS
Filter
59NDT
>
c
59NDT Setting
59NDT Delay
Inhibit 59NDT
59NDT Element
Enabled
Disabled
&
3Vo
General Pickup
General Pickup
c
Pickup
trip
&
Figure 3-29
Logic Diagram: Neutral Overvoltage Element (59N)
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