3 Operation Theory
PCS-978 Transformer Relay
3-81
Date: 2013-01-16
No.
Setting Item
Range
Step
Unit
Description
1 IntTurn.En
0: disable
1: enable
1
Logic setting of enabling/disabling inter-turn fault
protection.
2 IntTurn.OutMap
0000~FFFF
Tripping logic setting of inter-turn fault protection.
3.7 Overexcitation Protection (24)
3.7.1 Application
Overexcitation results from excessive applied voltage, possibly in combination with below-normal
frequency. Such condition may occur when a unit is on load, but are more likely to arise when it is
on open circuit, or at a loss of load occurrence. Transformers directly connected to generators are
in particular danger to experience overexcitation condition.
During overexcitation, field current of transformer rises greatly to cause excessive heating and
severe damage. The transformer, working magnetic flux density near the knee point, is subject to
overexcitation. Frequency range for normal operation is 45~55Hz for 50Hz working frequency of
power system and 55~65Hz for 60Hz working frequency of power system.
Overexcitation protection can be configured at any side of transformer through PCS-Explorer, and
it is recommended to be equipped at the side without OLTC tap.
3.7.2 Function
Overexcitation protection has following functions:
Voltage for protection calculation is RMS of three phase voltages and not affected by
frequency fluctuation.
Overexcitation multiple is calculated by voltage and frequency.
Two-stage definite-time overexcitation protection and one-stage definite-time overexcitation
alarm element are equipped.
One-stage inverse-time overexcitation protection including tripping and alarm functions is
equipped.
Overexcitation inverse-time curve is sectional linear curve, which has high adaptivity.
3.7.3 Protection Principle
Overexitation protection consists of definite-time protection and inverse-time protection.
Calculate overexcitation degree:
Degree of overexcitation can be evaluated by following overexcitation multiple:
*
*
/
f
U
n
Equation 3.7-1
Where:
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 ...