Voltage Protection: Neutral Overvoltage (59N); Figure 3-25 Logic Diagram: Neutral Overvoltage Element (59N) - Siemens 7SR10 Argus Series Manual

3.4.11

Voltage Protection: Neutral Overvoltage (59N)

Two Neutral Overvoltage (or Neutral Voltage Displacement) elements are provided 59NIT & 59NDT.
The relay utilises fundamental voltage measurement values for this function. The element can use a direct
measurement 3V0 connection from the voltage transformer or calculate values from a phase to neutral
connections from the voltage transformer.
The 59NIT element can be configured to be either definite time lag (DTL) or inverse definite minimum time
(IDMT),
59NIT Setting sets the pick-up voltage level (3V0) for the element.
An inverse definite minimum time (IDMT) can be selected using 59NIT Char. A time multiplier is applied to the
characteristic curves using the 59NIT Time Mult setting (M):
Alternatively, a definite time lag delay (DTL) can be chosen using 59NITChar. When Delay (DTL) is selected the
time multiplier is not applied and the 59NIT Delay (DTL) setting is used instead.
An instantaneous or definite time delayed reset can be applied using the 59NIT Reset setting.
The 59NDT element has a DTL characteristic. 59NDT Setting sets the pick-up voltage (3V0) and 59NDT Delay
the follower time delay.
Operation of the neutral overvoltage elements can be inhibited from:
Inhibit 59NIT
Inhibit59NDT
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.
59NIT Element
Disabled
Enabled
Inhibit 59NIT
VL1
ZPS
Filter
VL2
VL3
59NDT Element
Disabled
Enabled
Inhibit 59NDT

Figure 3-25 Logic Diagram: Neutral Overvoltage Element (59N)

©2018 Siemens Protection Devices Limited

1000
t
=

[ ]
op

A binary or virtual input.
A binary or virtual input.
59NIT Setting
59NIT Charact
59NIT Time Mult
59NIT Delay (DTL)
&
59NIT Reset
c
3V0
59NDT Setting
&
c

* M
ms

−
3V0 1

Vs
Pickup
trip
59NDT Delay
>
7SR10 Description of Operation
General Pickup
59NIT
General Pickup
59NDT
Chapter 1 Page 46 of 77