3 Operation Theory
PCS-978 Transformer Relay
3-115
Date: 2013-01-16
Direction
Element
U3P
Harmonic
Blocking
Element
I3P
St
Op
Direction signal
Hm blocking signal
[Alm_VTS(U3P)]
St
Op
St
Op
St
Op
Overcurrent
Element
Overcurrent
Element
Overcurrent
Element
Overcurrent
Element
Stage1
Stage2
Stage3
Stage4
Voltage
Control
Element
Voltage signal
Figure 3.12-1 Function diagram of phase overcurrent protection
3.12.3.2 Operation Criterion
The operation criterion of each stage ground overcurrent protection is:
p
I
> [
x.
50/51Pn.I_Set]
Equation 3.12-1
Where:
p
I
is measured phase current.
[
x.
50/51Pn.I_Set] is the current setting of stage n (n=1, 2, 3, or 4) of phase overcurrent protection
of x side.
If any phase current is greater than the setting of any stage enabled phase overcurrent protection,
the stage phase overcurrent protection will operate after time delay if voltage control element
operates (or voltage control element not enabled), directional element operates (or directional
element not enabled), and the stage protection will drop off instantaneously after fault current
disappears.
3.12.3.3 Time Curve
Phase overcurrent protection stage 1, stage 2 and stage 3 are definite-time characteristic and
each stage can perform instantaneous operation with the corresponding time delay setting at zero.
Stage 4 can be selected as definite-time or inverse-time characteristic, and inverse-time operating
time curve is as follows.
Summary of Contents for PCS-978
Page 1: ...PCS 978 Transformer Relay Instruction Manual NR Electric Co Ltd ...
Page 2: ......
Page 6: ...Preface PCS 978 Transformer Relay IV Date 2013 01 16 ...
Page 10: ...Preface PCS 978 Transformer Relay VIII Date 2013 01 16 ...
Page 62: ...3 Operation Theory PCS 978 Transformer Relay 3 p Date 2013 01 16 ...
Page 250: ...4 Supervision PCS 978 Transformer Relay 4 b Date 2013 01 16 ...
Page 264: ...4 Supervision PCS 978 Transformer Relay 4 14 Date 2013 01 16 ...
Page 266: ...5 Management PCS 978 Transformer Relay 5 b Date 2013 01 16 ...
Page 272: ...5 Management PCS 978 Transformer Relay 5 6 Date 2013 01 16 ...
Page 334: ...6 Hardware Description PCS 978 Transformer Relay 6 60 Date 2013 01 16 ...
Page 370: ...8 Human Machine Interface PCS 978 Transformer Relay 8 d Date 2013 01 16 ...
Page 404: ...8 Human Machine Interface PCS 978 Transformer Relay 8 34 Date 2013 01 16 ...
Page 406: ...9 Configurable Function PCS 978 Transformer Relay 9 b Date 2013 01 16 ...
Page 446: ...10 Communication PCS 978 Transformer Relay 10 26 Date 2013 01 16 ...
Page 448: ...11 Installation PCS 978 Transformer Relay 11 b Date 2012 10 09 ...
Page 456: ...11 Installation PCS 978 Transformer Relay 11 8 Date 2012 10 09 ...
Page 458: ...12 Commissioning PCS 978 Transformer Relay 12 b Date 2012 12 07 ...
Page 468: ...12 Commissioning PCS 978 Transformer Relay 12 10 Date 2012 12 07 ...
Page 470: ...13 Maintenance PCS 978 Transformer Relay 13 b Date 2012 10 09 ...
Page 474: ...13 Maintenance PCS 978 Transformer Relay 13 4 Date 2012 10 09 ...
Page 476: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 b Date 2012 10 09 ...
Page 478: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 2 Date 2012 10 09 ...
Page 480: ...15 Manual Version History PCS 978 Transformer Relay 15 2 Date 2013 01 16 ...