Siemens 7SC80 Manual page 126

Functions
2.3 Directional Overcurrent Protection 67, 67N
•
Measurement of the True RMS Value
The current amplitude is derived from the sampled value in accordance with the definition equation of
the true RMS value. This measurement method should be selected when higher harmonics are to be
considered by the function (e.g. in capacitor bank).
The type of the comparison values can be set under the following addresses:
67-3 element
67-2 element
67-1element
67-TOC element
67-TOC-1 element
67-TOC-2 element
67-TOC-3 element
67-TOC-4 element
67N-3 element
67N-2 element
67N-1element
67N-TOC element
67N-TOC-1 element Address 1646 67N-TOC-1 MEAS.
67N-TOC-2 element Address 1652 67N-TOC-2 MEAS.
67N-TOC-3 element Address 1658 67N-TOC-3 MEAS.
67N-TOC-4 element Address 1664 67N-TOC-4 MEAS.
Direction Characteristic
The direction characteristic, i.e. the position of the ranges "forward"" and "reverse" is set for the phase direc-
tional elements under address 1519 ROTATION ANGLE and for the ground directional element under address
1619 ROTATION ANGLE. The short-circuit angle is generally inductive in a range of 30° to 60°. This means
that usually the default settings of +45° for the phase directional elements and -45° for the ground directional
element can be maintained for the adjustment of the reference voltage, as they guarantee a safe direction
result.
Nevertheless, the following contains some setting examples for special applications
must be observed: With the phase directional elements, the reference voltage (fault-free voltage) for phase-to-
ground- faults is vertical on the short-circuit voltage. For this reason, the resulting setting of the angle of rota-
tion is (see also Section 2.3.8):
Ref. volt. angle of rotation = 90 - φ
With the ground directional element, the reference voltage is the short-circuit voltage itself. The resulting
setting of the angle of rotation is then:
Ref. volt. angle of rotation = -φ
It should also be noted for phase directional elements that with phase-to-phase faults, the reference voltage is
rotated between 0° (remote fault) and 30° (close-up fault) depending on the collapse of the faulty voltage.
This can be taken into account with a mean value of 15°:
Ref. volt. angle of rotation = 90 - φ
126
Address 1537 67-3 MEASUREM.
Address 1520 67-2 MEASUREM.
Address 1521 67-1 MEASUREM.
Address 1522 67-TOC MEASUR.
Address 1546 67-TOC-1 MEAS.
Address 1552 67-TOC-2 MEAS.
Address 1558 67-TOC-3 MEAS.
Address 1564 67-TOC-4 MEAS.
Address 1637 67N-3 MEASUREM.
Address 1620 67N-2 MEASUREM.
Address 1621 67N-1 MEASUREM.
Address 1622 67N-TOC MEASUR.
Phase directional element (phase-to-ground fault).
SC
Directional ground element (phase-to-ground fault).
SC
-15° Phase directional element (phase-to-phase fault).
SC
(Table 2-8). The following
SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017