ABB RELION REX640 Technical Manual page 618

Protection functions
Figure 351: Operation timer characteristic of IFPTOC function when Operation
principle = "Touch voltage based", Operating curve type = "Inverse time EN50522"
and UTp multiplier = 2.0. Characteristics are according to standard EN50522.
Maximum earthing Ris = 10 ohm.
Example 5c. Inverse time operation of IFPTOC, when
voltage based",
multiplier = 4.0 is illustrated in
(setting
maximum operate time of 5000 ms (settings
Max Op Tm ). Maximum earthing resistance value encountered in the protected
feeder is set to be 10 ohms (setting
= 1. For illustrating the operating speed requirement of protection, limits of earth
potential rise durations defined in standard EN50522 are shown for reference.
618
Operating curve type = "Inverse time EN50522" and setting UTp
Touch Vol Str Val ). IFPTOC is set to have minimum operate time 100 ms and
Figure 352 . Start value for operation is set to be 60 V
IDMT stage Min Op Tm, IDMT stage
Maximum earthing Ris ) and Reduction factor
1MRS759142 F
Operation principle = "Touch
Technical Manual
REX640