Functions
2.3 Directional Overcurrent Protection 67, 67N
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
110
2.3.10 Setting Notes
General
When selecting the directional time overcurrent protection in DIGSI, a dialog box appears with several tabs for
setting the associated parameters. Depending on the functional scope specified during configuration of the pro-
tective functions in addresses 115 67/67-TOC and 116 67N/67N-TOC, the number of tabs can vary.
If 67/67-TOC or 67N/67N-TOC = Definite Time is selected, then only the settings for the definite time
elements are available. If TOC IEC or TOC ANSI is selected, the inverse characteristics are also available.
The superimposed directional elements 67-2 and 67-1 or 67N-2 and 67N-1 apply in all these cases.
At address 1501 FCT 67/67-TOC, directional phase overcurrent protection may be switched ON or OFF.
Pickup values, time delays, and characteristic are set separately for phase protection and ground protection.
Because of this, relay coordination for ground faults is independent of relay coordination for phase faults, and
more sensitive settings can often be applied to directional ground protection. Thus, at address 1601 FCT
67N/67N-TOC, directional ground time overcurrent protection may be switched ON or OFF independent of the
directional phase time overcurrent protection.
Depending on the parameter 613 50N/51N/67N w., the device can either operate using measured values I
N
or the quantities 3I
0
calculated from the three phase currents. Devices featuring a sensitive ground current input
generally use the calculated quantity 3I
0
.
The directional orientation of the function is influenced by parameter 201 CT Starpoint (see Chapter 2.1.3).
Measurement Methods
The comparison values to be used for the respective element can be set in the setting sheets for the elements.
• Measurement of the Fundamental Harmonic (standard method):
This measurement method processes the sampled values of the current and filters in numerical order the
fundamental harmonic so that the higher harmonics or transient peak currents remain mostly unconsidered.
• Measurement of the True r.m.s. Value
The current amplitude is derived from the sampled value in accordance with the definition equation of the
true r.m.s. value. This measurement method should be selected when higher harmonics are to be consid-
ered by the function (e.g. in capacitor bank).
The type of the comparison values can be set under the following addresses:
67-2 element Address 1520 67-2 MEASUREM.
67-1 element Address 1521 67-1 MEASUREM.
67-TOC element Address 1522 67-TOC MEASUR.
67N-2 element Address 1620 67N-2 MEASUREM.
67N-1 element Address 1621 67N-1 MEASUREM.
67N-TOC element Address 1622 67N-TOC MEASUR.
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