3 Operation Theory
PCS-978 Transformer Relay
3-119
Date: 2013-01-16
Forward
Reverse
VT
CT
Direction
Element
Dir
Protected
Object
Figure 3.12-2 Connection of VT and CT of directional element
NOTE!
Symbol ” ” represents the polarity of current transformer.
Forward
Reverse
Uref(U1)
Idir(Ip)
Φsen+180°
Φsen
Figure 3.12-3 Directional characteristic of phase overcurrent protection
Effect of VT Circuit
When VT circuit fails (i.e. message [
x.
Alm_VTS] being issued) or VT is not put into service (i.e.
[
x.
In_VT] is “0”), if setting [
x.
50/51Pn.En_VTS_Blk
] is set to “1”, then directional element resets
instantaneously and directional phase overcurrent is blocked, and if the setting is set to”0” then
directional element picks up automatically and directional phase overcurrent becomes
non-directional ground overcurrent protection.
3.12.3.6 Harmonic Blocking Element
When phase overcurrent protection is set to protect transformer during transformer energization,
in order to prevent inrush current leading to maloperation of phase overcurrent protection,
harmonic blocking function can be selected for every stage of this relay.
Blocking mode is selectable between phase segregated blocking mode or phase crossing blocking
mode through the setting [
x.
50/51P.Opt_Hm_Blk], “0” for phase segregated blocking mode and “1”
for phase crossing blocking mode. If any phase harmonic meets the following criterion, harmonic
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 ...