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3 Operation Theory
PCS-978 Transformer Relay
3-169
Date: 2013-01-16
temperature of transformer increase and if the temperature reaches too high values the equipment
might be damaged. The insulation within the transformer will have forced ageing.
The phase overcurrent alarm element is equipped to monitor the load of transformer winding, and
when load current exceeds the transformer limit load current, phase overcurrent alarm element
can be applied to issuing alarm signals to remind field operators.
Besides, during overload of transformer, it is needed to initiate cooling system (such as cooling fan)
and blocking OLTC function of the tap of transformer. Therefore phase overcurrent alarm element
can also be applied to the initiation of cooling system and the blocking of OLTC function.
3.21.2 Function
Phase overcurrent alarm element has following functions:
Two-stage definite-time phase overcurrent alarm element with independent logic, current and
time delay settings.
Outputs of phase overcurrent alarm element only applied for alarm signals.
Fundamental current or 1
st
to 7
th
harmonic current is used for protection calculation.
Drop off coefficient of phase overcurrent alarm element is settable.
NOTE!
Users must declare current value calculation for thermal overload protection,
fundamental current or 1
st
to 7
th
harmonic current before making an order.
3.21.3 Operation Principle
Operation criterion:
p
I
> [50PAlmn.I_Set]
Equation 3.21-1
Where:
p
I
is phase current.
[51Almn.I_Set] is the current setting of stage n stage n (n=1, or 2) phase overcurrent alarm
element..
If any phase current is greater than the setting of any stage enabled phase overcurrent alarm
element, the stage phase overcurrent alarm element will operate after time delay and the stage
protection will drop off after the overload current disappear.
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 ...