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 3
I
0
calculated from the three phase currents. Devices featuring a sensitive ground current input
generally use the calculated quantity 3
I
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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