3I2F; Iub - ABB REX 521 Technical Reference Manual, Standard Configurations

REX 521
7.1.7.
7.1.8.
84
Protection Relay
Technical Reference Manual, Standard Configurations
3I2f>
The function block 3I2f> can be used for doubling the set start current of overcurrent
protection in a transformer magnetizing inrush situation or at motor start-up.
3I2f>
3I /I >
1f
2f
3dI/dt>
GROUP START
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Three-phase transformer inrush and motor start-up current detector inrush3, 3I2f>
Ratio I 2f/I 1f
Start current
Operation mode
Operation accuracy
Start time
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Iub>
The phase discontinuity protection function block Iub> is designed to be used for
protection against broken phase conductors in distribution networks. Definite-time
(DT) characteristic is always used.
5...50%
0.10...5.00 x ln
Not in use
Inrush mode
Start-up mode
Note! The values below apply when f/fn=0.95...1.05
Current meas.: ±2.5% of set value or ±0.01 x ln
Ratio I 2f/I 1f measurement: ±5.0% of set value
Internal time <32 ms
Total time <40 ms
1MRS 751802-MUM