Siemens SIPROTEC 7UM62 - Page 479

Technical Data
4.8 Differential Protection (ANSI 87T) for Transformers
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
479
Tolerances
Influencing Variables for Pickup Values
Figure 4-8 Pickup Characteristic of the Transformer Differential Protection
Figure 4-9 Restraining Influence of 2nd Harmonic in Transformer Differential Protection
With Preset Transformer Parameters
- Pickup Characteristic ± 3 % of setpoint (for I < 5 · I
N
)
- Inrush Restraint ± 3 % of setting value (for I
2fN
/I
fN
≥ 15 %)
- Additional Delay Times ± 1 % of setting value or 10 ms
Power supply direct voltage in range 0.8 ≤ U
Aux
/U
AuxN
≤ 1.15 ≤ 1 %
Temperature in range 23.00 °F (–5 °C) ≤ Θ
amb
≤ 131.00 °F (55 °C) ≤ 0.5 % / 10 K
Frequency in range 0.95 ≤ f/f
N
≤ 1.05 ≤ 1 % (see also Figure 4-11)