ABB RELION REX640 Technical Manual page 616

Protection functions
where U
[A], I
setting
When
protection operate time as a function of estimated touch voltage
account the effect of
In IFPTOC function, the preferred presentation of operation timer characteristics
is by plotting the protection operate time as a function of permissible/estimated
touch voltage as illustrated in
Consider next three examples with
Example 5a. Inverse time operation of IFPTOC, when
voltage based",
multiplier = 1.0 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 touch
voltage durations defined in standard EN50522 are shown for reference.
616
in terms of fault resistance depends also on the network parameters
(nominal voltage, damping and detuning) as described by
is the nominal phase-to-earth voltage [V], I
PE
is the detuning [A], U
v
Maximum earthing Ris in primary ohms.
Operating curve type = "Inverse time EN50522" is selected, then the
Reduction factor ) is according to
Operating curve type = "Inverse time EN50522" and setting UTp
Touch Vol Str Val ). IFPTOC is set to have minimum operate time 100 ms and
Touch Vol Str Val in primary volts and R
is setting
F
Figure 350 Figure 351
,
Operating curve type = "Inverse time EN50522":
Figure 350
. Start value for operation is set to be 20 V
IDMT stage Min Op Tm, IDMT stage
Maximum earthing Ris ) and Reduction factor
1MRS759142 F
Equation 126
(Equation 126)
is the total system damping
d
(taking
Equation 127
:
(Equation 127)
Figure 352
and .
Operation principle = "Touch
Technical Manual
.
is
E
REX640