ABB Relion 670 series - Introduction; Principle of operation; Directional impedance element for mho characteristic ZDMRDIR (21 D)

Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Additional distance protection
directional function for earth faults
ZDARDIR
S00346 V1 EN
-
6.6.1 Introduction
The phase-to-ground impedance elements can be optionally supervised by a phase
unselective directional function based on symmetrical components.
6.6.2 Principle of operation
6.6.2.1 Directional impedance element for mho characteristic ZDMRDIR (21D)
The evaluation of the directionality takes place in Directional impedance element for
mho characteristic (ZDMRDIR ,21D). Equation 50 and equation 51 are used to classify
that the fault is in the forward direction for phase-to-ground fault and phase-to-phase
fault respectively.
0.85 1 0.15 1
Re
V A V AM
AngDir Ang AngNeg s
IA
× + ×
- < <
EQUATION1618 V1 EN (Equation 50)
0.85 1 0.15 1
Re
V AB V ABM
AngDir Ang AngNeg s
IAB
× + ×
- < <
EQUATION1620 V1 EN (Equation 51)
Where:
AngDir Setting for the lower boundary of the forward directional characteristic, by default set to
15 (= -15 degrees)
AngNegRes Setting for the upper boundary of the forward directional characteristic, by default set to
115 degrees, see figure 142 for mho characteristics.
V1A Positive sequence phase voltage in phase A
V1AM Positive sequence memorized phase voltage in phase A
IA Phase current in phase A
V1AB Voltage difference between phase A and B (B lagging A)
V1ABM Memorized voltage difference between phase A and B (B lagging A)
IAB Current difference between phase A and B (B lagging A)
1MRK505222-UUS C Section 6
Impedance protection
277
Technical reference manual