3
Operation
Theory
PCS-978 Transformer Relay
3-120
Date: 2013-01-16
blocking condition is satisfied.
But when any phase current is greater than the setting [x.50/51P.I_Rls_HmBlk], phase overcurrent
protection does not be blocked by harmonic even if blocking condition is satisfied.
Operation criterion:
p
nd
2
_
p
I
]
2
Hm
_
K
.
P
51
/
50
x.
[
I
Equation 3.12-6
Where:
nd
p
I
2
_
is second harmonic of phase current
p
I
is fundamental component of phase current.
[
x.
50/51P.K_Hm2] is harmonic blocking coefficient and recommended value is 0.15.
If fundamental component of any phase current is lower than the minimum operating current
(
0.04In
)
, then harmonic calculation is not carried out and harmonic blocking element does not
operate.
3.12.4 Logic
Logic diagram of phase overcurrent is shown in the following figure, including phase overcurrent
element, voltage control element and directional element, harmonic blocking element and
enabling and blocking logic of the protection.
Logic schemes of phase overcurrent protection of each stage are same except that stage 4 can be
selected as inverse-time characteristic, and that stage 4 is taken as an example to show the logic.
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 ...