7SR210 & 7SR220 Description of Operation
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3.15 Voltage Protection: Neutral Overvoltage (59N) – 7SR22
Two Neutral Overvoltage (or Neutral Voltage Displacement) elements are provided in the 7SR22 relay.
59N Voltage Source
setting selects the source of the residual voltage to be measured. The voltage is measured
directly from the Vx input or derived from the line voltages where suitable VT connections are present. The relay
utilises fundamental voltage measurement values for this function.
One of the elements can be configured to be either definite time lag (DTL) or inverse definite minimum time
(IDMT).
The Neutral Inverse Time Lag
59NIT Setting
sets the pick-up voltage level (3V
0
) 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 second element has a DTL characteristic. The Neutral Definite Time Lag
59NDT Setting
sets the pick-up
voltage (3V
0
) and
59NDT Delay
the follower time delay.
Operation of the neutral overvoltage elements can be inhibited from:
Inhibit 59NIT
A binary or virtual input, function key or remote data Comms.
Inhibit59NDT
A binary or virtual input, function key or remote data Comms.
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.
Figure 3.15-1 Logic Diagram: Neutral Overvoltage Element
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s
ú
û
ù
ê
ë
é
-
=
1
M
t
Vs
3Vo
op
Summary of Contents for Argus 7SR21
Page 1: ...Energy Management 7SR21 7SR22 Argus Overcurrent Relay Reyrolle Protection Devices ...
Page 2: ......
Page 4: ...Contents 7SR11 and 7SR12 Page 2 of 2 2018 Siemens Protection Devices Limited ...
Page 185: ...7SR210 Settings Guide Unrestricted 2018 Siemens Protection Devices Limited Page 61 of 61 ...
Page 277: ...7SR220 Settings Guide Unrestricted Page 72 of 107 2013 Siemens Protection Devices Limited ...
Page 382: ...7SR220 Technical Manual Chapter 4 Page 2 of 96 2017 Siemens Protection Devices Limited ...
Page 386: ...7SR220 Technical Manual Chapter 4 Page 6 of 96 2017 Siemens Protection Devices Limited ...
Page 398: ...7SR220 Technical Manual Chapter 4 Page 18 of 96 2017 Siemens Protection Devices Limited ...
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Page 466: ...7SR220 Technical Manual Chapter 4 Page 86 of 96 2017 Siemens Protection Devices Limited ...
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