ABB Relion 670 Series Technical Reference Manual page 246

Section 6
Impedance protection
240
The IED can be used up to the highest voltage levels. It is suitable for the protection of
heavily loaded lines and multi-terminal lines where the requirement for tripping is
one-, two- and/or three-pole.
The independent measurement of impedance for each fault loop together with a
sensitive and reliable built in phase selection makes the function suitable in
applications with single phase autoreclosing.
Built-in adaptive load compensation algorithm prevents overreaching at phase-to-
ground faults on heavily loaded power lines, see figure 116.
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Operation area Operation area
Operation area
No operation area No operation area
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IEC07000117 V1 EN
Figure 116: Load encroachment influence on the offset mho characteristic
The distance protection zones can operate, independent of each other, in directional
(forward or reverse) or non-directional mode (offset). This makes them suitable,
together with different communication schemes, for the protection of power lines and
cables in complex network configurations, such as parallel lines, multi-terminal lines
and so on.
The possibility to use the phase-to-ground quadrilateral impedance characteristic
together with the mho characteristic increases the possibility to overcome eventual lack
of sensitivity of the mho element due to the shaping of the curve at remote end faults.
The integrated control and monitoring functions offer effective solutions for operating
and monitoring all types of transmission and sub-transmission lines.
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1MRK505222-UUS C
Technical reference manual