Table 357: OEXPVPH (24) Group settings (advanced)
Name Values (Range) Unit Step Default Description
t1_UserCurve 0.00 - 9000.00 s 0.01 7200.00 Time delay t1 (longest) for tailor made
curve, in sec
t2_UserCurve 0.00 - 9000.00 s 0.01 3600.00 Time delay t2 for tailor made curve, in sec
t3_UserCurve 0.00 - 9000.00 s 0.01 1800.00 Time delay t3 for tailor made curve, in sec
t4_UserCurve 0.00 - 9000.00 s 0.01 900.00 Time delay t4 for tailor made curve, in sec
t5_UserCurve 0.00 - 9000.00 s 0.01 450.00 Time delay t5 for tailor made curve, in sec
t6_UserCurve 0.00 - 9000.00 s 0.01 225.00 Time delay t6 (shortest) for tailor made
curve, in sec
Table 358: OEXPVPH (24) Non group settings (basic)
Name Values (Range) Unit Step Default Description
MeasuredV PosSeq
AB
BC
CA
- - AB Selection of measured voltage
MeasuredI AB
BC
CA
PosSeq
- - AB Selection of measured current
GlobalBaseSel 1 - 12 - 1 1 Selection of one of the Global Base Value
groups
9.4.6 Monitored data
PID-3514-MONITOREDDATA v4
Table 359: OEXPVPH (24) Monitored data
Name Type Values (Range) Unit Description
TMTOTRIP REAL - s Calculated time to trip for overexcitation,
in sec
VPERHZ REAL - V/Hz Voltage to frequency ratio in per-unit
THERMSTA REAL - % Overexcitation thermal status in % of trip
pickup
9.4.7 Operation principle
M5854-3 v8
The importance of Overexcitation protection (OEXPVPH, 24) function is growing as the power
transformers as well as other power system elements today operate near their designated limits
most of the time.
Modern design transformers are more sensitive to overexcitation than earlier types. This is a result
of the more efficient designs and designs which rely on the improvement in the uniformity of the
excitation level of modern systems. If an emergency that causes overexcitation does occur,
transformers may be damaged unless corrective action is taken. Transformer manufacturers
recommend an overexcitation protection as a part of the transformer protection system.
Section 9 1MRK 502 066-UUS B
Voltage protection
638
Technical manual
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