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3 Operation Theory
PCS-978 Transformer Relay
3-83
Date: 2013-01-16
t(s)
n0
n1
n2
n4
t1 t3 t4
n3
n5
t0
n6
n7
n8
n9
t2
t5
t6
t7
t8
t9
*
*
/
f
U
0
Figure 3.7-1 Inverse-time characteristic of overexcitation protection
The main harm of overexcitation to transformer is overheat, so accumulation method is adopted
and accumulate the time delay according to curve time corresponding to calculated overexcitation
multiple. When accumulated time delay is greater than the operating time delay, inverse-time
overexcitation protection operates. Dissipating process is also simulated, when overexcitation
multiple is less than the minimum overexcitation multiple setting, the accumulated value
decreases to 0 gradually. If overexcitation protection operates and overexcitation condition
disappears, thermal accumulation value decreases to zero in 10s.
Overexcitation multiple comprises overexcitation information at current instant and also
overexcitation information integrated over various time intervals from its beginning.
Inverse-time characteristic curve can be specified by several overexcitation multiple settings, and
the relation between various settings of n and t are:
n0≥n1 ≥ n2 ≥ n3 ≥ n4 ≥ n5 ≥ n6 ≥ n7 ≥ n8 ≥ n9
t0 ≤t1 ≤ t2 ≤ t3 ≤ t4 ≤ t5 ≤ t6 ≤ t7≤ t8 ≤ t9
3.7.4 Logic
Two-stage definite-time overexcitation protection with independent current and time delay settings.
Stage 1 and stage 2 has identical logic diagrams but stage 1 for trip and stage 2 for alarm.
On-stage inverse-time overexcitation operates to trip and issued the alarm signal.
SIG
[24DT1.En1]
SIG
[24DT1.En2]
SIG
[24DT1.Blk]
&
EN
[24DT1.En]
&
SIG
>[24DT1.K_Set]
*
*
/
f
U
[24DT1.t_Op] 0ms
[24DT1.Op]
Figure 3.7-2 Logic diagram of stage 1 definite-time overexcitation protection
Where:
Содержание PCS-978
Страница 1: ...PCS 978 Transformer Relay Instruction Manual NR Electric Co Ltd ...
Страница 2: ......
Страница 6: ...Preface PCS 978 Transformer Relay IV Date 2013 01 16 ...
Страница 10: ...Preface PCS 978 Transformer Relay VIII Date 2013 01 16 ...
Страница 62: ...3 Operation Theory PCS 978 Transformer Relay 3 p Date 2013 01 16 ...
Страница 250: ...4 Supervision PCS 978 Transformer Relay 4 b Date 2013 01 16 ...
Страница 264: ...4 Supervision PCS 978 Transformer Relay 4 14 Date 2013 01 16 ...
Страница 266: ...5 Management PCS 978 Transformer Relay 5 b Date 2013 01 16 ...
Страница 272: ...5 Management PCS 978 Transformer Relay 5 6 Date 2013 01 16 ...
Страница 334: ...6 Hardware Description PCS 978 Transformer Relay 6 60 Date 2013 01 16 ...
Страница 370: ...8 Human Machine Interface PCS 978 Transformer Relay 8 d Date 2013 01 16 ...
Страница 404: ...8 Human Machine Interface PCS 978 Transformer Relay 8 34 Date 2013 01 16 ...
Страница 406: ...9 Configurable Function PCS 978 Transformer Relay 9 b Date 2013 01 16 ...
Страница 446: ...10 Communication PCS 978 Transformer Relay 10 26 Date 2013 01 16 ...
Страница 448: ...11 Installation PCS 978 Transformer Relay 11 b Date 2012 10 09 ...
Страница 456: ...11 Installation PCS 978 Transformer Relay 11 8 Date 2012 10 09 ...
Страница 458: ...12 Commissioning PCS 978 Transformer Relay 12 b Date 2012 12 07 ...
Страница 468: ...12 Commissioning PCS 978 Transformer Relay 12 10 Date 2012 12 07 ...
Страница 470: ...13 Maintenance PCS 978 Transformer Relay 13 b Date 2012 10 09 ...
Страница 474: ...13 Maintenance PCS 978 Transformer Relay 13 4 Date 2012 10 09 ...
Страница 476: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 b Date 2012 10 09 ...
Страница 478: ...14 Decommissioning and Disposal PCS 978 Transformer Relay 14 2 Date 2012 10 09 ...
Страница 480: ...15 Manual Version History PCS 978 Transformer Relay 15 2 Date 2013 01 16 ...