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3
Operation
Theory
PCS-978 Transformer Relay
3-6
Date: 2013-01-16
secondary currents for delta/wye, so phases of each side secondary current must be
compensated by this phase compensation.
The following transforming method is based on the assumptions listed here:
1) Each side three-phase CT of transformer shall be connected in star type.
2) The positive polarity of each side three-phase CT shall be at busbar side.
The wiring connection of HV, MV and LV sides may be different, so it is needed to compensate
phase of each side current of transformer for calculation of current differential protection. There
are two
transforming methods for phase compensation: Δ→Y and Y→Δ, and different transforming
methods will result in the difference.
Phase compensation is controlled by the following settings:
1) [Clk_MVS_WRT_HVS],[Clk_LVS_WRT_HVS]: the wiring o
’clock of MV/LV side with respect to
HV side, is the parameter shown on transformer nameplate with the range of 0~11, and need
no further calculation.
2) [Clk_PhComp]: the
target o’clock each side current will be shifted to for phase compensation.
3) [En_I0Elim_HVS], [En_I0Elim_MVS] and [En_I0Elim_LVS]: logic settings to enable
zero-sequence current elimination for phase compensation of each side of transformer. The
setting is recommended to be set to “1” in general condition, and only if one side of transformer,
without eathing transformer being connected to, is not grounded, the setting of corresponding
side is recommended to be set to “0”.
For example:
The vector group of a transformer is
Y0/Δ11 and the target o’clock ([Clk_PhComp]) is set to “11”.
Therefore, the setting [Clk_LVS_WRT_HVS] should be set to
“11”.
1) For HV side, with reference to the set target o'clock the o'clock of HV side is 1 (i.e. wiring
o
’clock 12-target o’clock 11) clock, so the matrix of relative o’clock 1 is adopted to
compensate HV side current.
2) For LV side, with reference to the set target o'clock the o'clock of HV side is 0 (i.e. wiring
o
’clock 11- target o’clock 11), so the matrix of relative o’clock 0 is adopted to compensate LV
side current.
If an earthing transformer is connected outside the protection zone of differential protection,
the setting [En_I0Elim_HVS(or LVS)] could be disabled, i.e. set to 0.
If an earthing transformer is connected within the protection zone of differential protection,
then zero-sequence current must be eliminated and otherwise differential protection may
operate unexpectively during an external fault. Therefore the setting [En_I0Elim_HVS(or LVS)]
must be enabled, i.e. set to 1.
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 ...