7SR210 & 7SR220 Description of Operation
Unrestricted ©2018 Siemens Protection Devices Limited
Page 25 of 94
Section 3: Protection Functions
3.1
Current Protection: Phase Overcurrent (67, 51, 50)
All phase overcurrent elements can be set to measure either fundamental frequency RMS or True RMS current
i.e.
True RMS current: -
50 Measurement
= RMS
51 Measurement
= RMS
Fundamental Frequency RMS current: -
50 Measurement
= Fundamental
51 Measurement
= Fundamental
3.1.1
Directional Control of Overcurrent Protection (67) – 7SR22
The directional element produces forward and reverse outputs for use with overcurrent elements. These outputs
can then be mapped as controls to each shaped and instantaneous over-current element.
If a protection element is set as non-directional then it will operate independently of the output of the directional
detector. However, if a protection element is programmed for forward directional mode then operation will occur
only for a fault lying within the forward operate zone. Conversely, if a protection element is programmed for
reverse directional mode then operation will occur only for a fault lying within the reverse operate zone. Typically
the forward direction is defined as being ‘away’ from the busbar or towards the protected zone.
The Characteristic angle is the phase angle by which the polarising voltage must be adjusted such that the
directional detector gives maximum sensitivity in the forward operate zone when the current is in phase with it.
The reverse operate zone is the mirror image of the forward zone.
Voltage polarisation is achieved for the phase-fault elements using the quadrature voltage i.e. at unity power
factor I leads V by 90
°
. Each phase current is compared to the voltage between the other two phases: -
I
L1
~ V
23
I
L2
~ V
31
I
L3
~ V
12
The characteristic angle can be user programmed to any angle between -95
°
and +95
°
using the
67 Char Angle
setting. The voltage is the reference phasor (V
ref
) and the
67 Char Angle
setting is added to this to adjust the
forward and reverse zones.
The centre of the forward zone is set by (V
ref
Angle +
67 Char Angle
) and should be set to correspond with I
fault
Angle for maximum sensitivity i.e.
For fault current of -60
°
(I lagging V by 60
°
) a
67 Char Angle
of
+30
°
is required for maximum sensitivity
(i.e. due to quadrature connection 90
°
- 60
°
= 30
°
)
OR
For fault current of -45
°
(I lagging V by 45
°
) a
67 Char Angle
of
+45
°
is required for maximum sensitivity
(i.e. due to quadrature connection 90
°
- 45
°
= 45
°
).
Two-out-of-three Gate
When the
67 2-Out-Of-3 Logic
setting is set to
Enabled
, the directional elements will only operate for the
majority direction, e.g. if I
L1
and I
L3
are detected as forward flowing currents and I
L2
is detected as reverse current
flow, phases L1 and L3 will operate forwards, while phase L2 will be inhibited.
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 ...
Page 414: ...7SR220 Technical Manual Chapter 4 Page 34 of 96 2017 Siemens Protection Devices Limited ...
Page 466: ...7SR220 Technical Manual Chapter 4 Page 86 of 96 2017 Siemens Protection Devices Limited ...
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