Figure 350: Operation timer characteristic of IFPTOC function when Operation
principle = “Touch voltage based”, Operating curve type = “Inverse time EN50522”
and Operating curve type = 1.0. Characteristics are according to standard EN50522.
Maximum earthing Ris = 10 ohm.
Example 5b. Inverse time operation of IFPTOC, when
Operation principle = “Touch
voltage based”,
Operating curve type = “Inverse time EN50522” and setting UTp
multiplier = 2.0 is illustrated in
. Start value for operation is set to be 40 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.
1MRS759142 F
Protection functions
REX640
Technical Manual
617