ABB RELION REX640, Technical Manual, Page: 618 / 1960

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