3
Operation
Theory
PCS-978 Transformer Relay
3-130
Date: 2013-01-16
NOTE!
Symbol ” ” represents the polarity of current transformer.
Forward
Reverse
Uref(3U0)
Idir(3I0 or IN)
Φsen
Figure 3.13-3 Directional characteristic of ground overcurrent protection
Effect of VT Circuit
When VT circuit fails (i.e. message [x.Alm_VTS] being issue) or VT is not put into service (i.e.
[x.
In_VT] is “0”), if setting [x.50/51Gn.En_VTS_Blk] is set to “1”, then residual directional element
resets instantaneously and directional ground overcurrent is blocked, and if the setting is set to”0”
then residual directional element picks up automatically and directional ground overcurrent
becomes non-directional ground overcurrent protection.
3.13.3.5 Harmonic Blocking Element
In order to prevent effects of sympathetic inrush current on ground overcurrent relay, harmonics
blocking function can be selected for every stage of this relay.
When the percent of second harmonic to fundamental component of zero sequence current is
greater than setting [x.50/51G.K_Hm2], harmonic blocking element operates to block ground
overcurrent protection if logic setting [x.50/51Gn.En_Hm2_Blk] (n=1, 2, 3 or 4) enabled
When residual current is greater than the setting [x.50/51G.3I0_Rls_HmBlk], ground overcurrent
protection does not be blocked by harmonic even if following blocking criterion is satisfied.
Operation criterion:
0
2
_
0
]
2
_
.
51
/
50
.
[
I
Hm
K
G
x
I
nd
Equation 3.13-6
Where:
nd
I
2
_
0
is second harmonic of zero sequence current
0
I
is fundamental component of zero sequence current.
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 ...