Cooling - ABB RET650 Technical Manual
Relion 650 series
transformer protection
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Also See for RET650:
- Applications manual (392 pages) ,
- Commissioning manual (112 pages) ,
- Product manual (70 pages)
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Section 9
Voltage protection
9.4.7.3
228
IEEE OVEREXCITATION CURVES
Time (s)
1000
100
10
1
1
2
3
IEC09000115 V1 EN
Figure 100:
Delays inversely proportional to the square of the overexcitation
The critical value of excitation M is determined via OEXPVPH setting V/Hz>>. V/
Hz>> can be thought of as a no-load voltage at rated frequency, where the inverse law
should be replaced by a short definite delay, tMin. If, for example, V/Hz>> = 140 %,
then M is according to equation 83.
(
)
V Hz>> / f
=
=
M
1.40
Ur/fr
IECEQUATION2286 V1 EN
Cooling
The overexcitation protection function (OEXPVPH) is basically a thermal protection,
therefore a cooling process has been introduced. An exponential cooling process is
4
5
10
OVEREXCITATION IN %
1MRK 504 135-UEN A
kForIEEE
=
60
=
kForIEEE
20
=
kForIEEE
10
= 9
kForIEEE
=
kForIEEE
8
= 7
kForIEEE
=
kForIEEE
6
=
kForIEEE
5
=
kForIEEE
4
=
kForIEEE
3
=
kForIEEE
2
= 1
kForIEEE
20
30
40
(M-Emaxcont)*100)
IEC09000115-1-en.vsd
(Equation 83)
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