ABB RELION 650 SERIES, Technical Manual

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7.4.7.3 External polarizing for earth-fault function
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The individual steps within the protection can be set as non-directional. When this
setting is selected, it is possible via the function binary input BLKSTx to provide
external directional control (that is, torque control) by, for example, using one of
the following functions if available in the IED:
1. Distance protection directional function.
2. Negative sequence polarized general current and voltage multi purpose
protection function.
7.4.7.4 Directional detection for earth fault function
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Zero sequence components will be used for detecting directionality for the earth
fault function. In some cases, zero sequence quantities might detect directionality
incorrectly. In such a scenario, negative sequence quantities will be used. The user
can select either zero sequence components or negative sequence components for
detecting directionality with the parameter
SeqTypeIPol . I3PDIR input is always
connected to the same source as I3P input.
7.4.7.5 Base quantities within the protection
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The base quantities are entered as global settings for all functions in the IED. Base
current (
IBase ) shall be entered as rated phase current of the protected object in
primary amperes. Base voltage ( UBase ) shall be entered as rated phase-to-phase
voltage of the protected object in primary kV.
7.4.7.6 Internal earth-fault protection structure
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The protection is internally divided into the following parts:
1. Four residual overcurrent steps.
2. Directional supervision element for residual overcurrent steps with integrated
directional comparison step for communication based earth-fault protection
schemes (permissive or blocking).
3. Second harmonic blocking element with additional feature for sealed-in
blocking during switching of parallel transformers.
4. Switch on to fault feature with integrated Under-Time logic for detection of
breaker problems during breaker opening or closing sequence.
7.4.7.7 Four residual overcurrent steps
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Each overcurrent step uses operating quantity Iop (residual current) as the
measuring quantity. Each of the four residual overcurrent steps has the following
built-in facilities:
1MRK 506 382-UEN A
Section 7
Current protection
Line distance protection REL650 2.2 IEC 195
Technical manual