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3 Operation Theory
PCS-978 Transformer Relay
3-89
Date: 2013-01-16
NOTE!
Inverse-time overexcitation protection is set with reference to the curve given by
the transformer manufactory. The relation between all settings of inverse-time overexcitation
protection is:
[24IDMT.K9_Set]<[24IDMT.K8_ Set
]<…<[24IDMT.K1_Set]<[24IDMT.K0_ Set]
[24IDMT.t0_Op]<[ 24IDMT.t1_ Op
]<…<[24IDMT.k8_ Op] <[24IDMT.t9_ Op]
3.8 Frequency Protection (81)
3.8.1 Application
In case of frequency decline due to lack of active power in the power system, underfrequency
protection operates to shed part of the load according to the declined value of frequency to
re-balance the power supply and the load. On the contrary, if the power frequency of regional rises
due to the active power excess demand, overfrequency protection operates to perform generator
rejection to shed part of the generators automatically according to the rising frequency so that
power supply and the load are re-balanced.
3.8.2 Function
Underfrequency Protection
In order to prevent possible maloperation of underfrequency protection in conditions of high
harmonics, voltage circuit failures and so on, such blocking measures are carried out as follows:
a) Blocking in undervoltage condition
If the positive voltage U
<
0.15Un, the calculation of protection is not carried out and the output
relay will be blocked.
b) df/dt blocking element
If
-
df/dt
≥
[81U.df/dt_Blk], the calculation of protection is not carried out and the output relay will
be blocked. The blocking element will not be released automatically until the system frequency
recovers to be less than the setting [81U.f_Pkp].
c) frequency over-range blocking element
If the system frequency is less than the setting [f_low_FreqAlm] or greater than the setting
[f_High_FreqAlm], frequency measurement is decided to be abnormal and output relays are
blocked.
Overfrequency Protection
In order to prevent possible maloperation of overfrequency protection in conditions of high
harmonics, voltage circuit failures and so on, such blocking measures are carried out as follows:
a) Blocking in undervoltage condition
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 ...