E32IV is a SELOGIC control bit that gates the zero-sequence
V-polarized (and channel-IP I-polarized) ground directional elements.
When E32IV = 1 the V/I paths are allowed to operate; when 0
they are blocked regardless of current/voltage.
E32IV = 1 continuously in solidly grounded systems.52a or breaker/isolator logic if the zero-sequence source can be removed.
If ILOP (loss of potential) asserts and the relay’s LOP blocking is enabled,
the V-polarized path is blocked even if E32IV = 1.
ILOP is the relay word for detected VT problems (open fuse, wiring fault, etc.).
With LOP blocking enabled, asserting ILOP disables voltage-dependent functions,
including the V-polarized ground directional path, to prevent spurious operation.
LOP blocking does not necessarily inhibit all non-voltage functions (e.g., pure overcurrent); check your scheme’s logic and supervision.
Set to Y or Y1 so that when ILOP asserts the relay blocks voltage-polarized ground directionals and distance elements, automatically switching to the current-polarized channel.
Mode Y1 also blocks permissive overreaching transfer trip (POTT) keying whenever ORDER selects a voltage channel.
Best-Choice logic tries multiple ground directional “paths†and uses the first
eligible decision as per this string:
Q = negative-sequence (Iâ‚‚), V = V-polarized (3Vâ‚€ vs IG),
I = I-polarized (channel IP).
QV — try Q first; if Q is not eligible or inhibited, use V.VQ — prefer V-polarized; Q is the fallback.QVI — full chain: Q → V → I.The input accepts 2–3 characters, uppercase; unknown letters are ignored.
Opens a compact table showing each path’s eligibility and forward/reverse result: Q (I₂-based), V (3V₀-polarized), and I (channel IP), plus gating bits (e.g., E32IV, ILOP) and the selected path as dictated by ORDER.
Use it while dragging phasors or changing thresholds to see why the relay prefers a given path.
The Q-path gives ground-fault direction using negative-sequence current only. It’s fast and resilient to loss of potential. Eligibility is supervised by I₂ pickups and restraints to avoid misdirection during system unbalance/CT saturation.
3|Iâ‚‚| ≥ 50QFP3|Iâ‚‚| ≥ 50QRP|Iâ‚‚| > a₂·|Iâ‚||Iâ‚‚| > k₂·|Iâ‚€|
Internal thresholds Z2F / Z2R shape the Q-element forward/reverse decision regions.
Forward-directional negative-sequence current pickup on 3Iâ‚‚. Set above normal unbalance
and below the minimum I₂ for forward faults. Typical AUTO: ≈0.50 A (5 A CT) or 0.10 A (1 A CT).
a₂ restraint; don’t set 50QFP so high that genuine faults lose eligibility.
Reverse-directional negative-sequence pickup on 3Iâ‚‚. Like 50QFP but for reverse operation.
Typical AUTO: ≈0.25 A (5 A CT) or 0.05 A (1 A CT).
In weak reverse-source conditions, consider a slightly more sensitive setting than forward.
Security threshold against load unbalance: requires |Iâ‚‚| > a₂·|Iâ‚| before enabling Q-directionals.
a₂ ≈ 0.10; raise if system has persistent negative-sequence unbalance.Limits false direction when a healthy system produces small I₂ due to unequal phases or CT errors.
Requires |I₂| > k₂·|I₀| to assert the Q-path for ground faults when V/I paths are operable.
Adds security when residual Iâ‚€ is present but not fault-indicative.
k₂ ≈ 0.20 is a good starting point.Internal Z₂ magnitude/phase threshold shaping the forward decision region of the Q-element. Range (model-dependent) is typically broad enough for line applications.
Zâ‚‚F ≈ |Zâ‚|/2.Zâ‚‚R exceeds Zâ‚‚F by a small offset for direction separation.As for Zâ‚‚F but for reverse. Keep slightly higher than Zâ‚‚F to prevent overlap of FWD/REV regions.
Z₂R = Z₂F + Δ, with Δ ≈ 0.1–0.2 Ω (5 A CT scaling) or proportional for 1 A.This is a model/app parameter (not a named SEL setting) representing the sensitivity used in your channel IP I-polarized ground directional. It typically aligns with a term in the channel-IP decision that includes something like a \((0.05)^2\) factor.
Use it to explore how tight/loose the I-polarized path admits direction; document any mapping you use to actual relay settings.
Two complementary ground directionals: V-polarized compares residual voltage to residual current, and I-polarized (channel IP) uses current polarization when VTs are unreliable/unavailable.
3|Iâ‚€| ≥ 50GFP3|Iâ‚€| ≥ 50GRP|Iâ‚€| > a₀·|Iâ‚|
V-path torque ~ \(\mathrm{Re}\{\,3V_0 \cdot (I_G \cdot 1\angle Z_{0L})^{*}\,\}\).
The line angle \(Z_{0L} = \angle Z_0\) steers FWD vs REV.
Thresholds Z0F/Z0R shape forward/reverse decision regions.
Forward residual ground current pickup on 3Iâ‚€ for V/I paths.
Typical AUTO: ≈0.50 A (5 A CT) or 0.10 A (1 A CT).
aâ‚€ to avoid enabling direction on noisy Iâ‚€.
Reverse residual ground current pickup on 3Iâ‚€ for V/I paths.
Typical AUTO: ≈0.25 A (5 A CT) or 0.05 A (1 A CT).
Requires |Iâ‚€| > a₀·|Iâ‚| before enabling zero-sequence directionals. Improves security
against small residual currents from load imbalance/CT errors.
a₀ ≈ 0.10.Internal Z₀ threshold for the forward decision surface of the V-polarized element.
|Zâ‚€|/2 from your line model.Zâ‚€R in testing.Internal Zâ‚€ threshold for the reverse decision surface. Keep slightly higher than Zâ‚€F for separation.
Auto mode applies +/-0.30 Ω secondary (scaled to the nominal CT class) with a small deadband before declaring z-based comparators true.
Choose Manual to use the exact Z2F/Z2R/Z0F/Z0R values entered above.
This angle aligns the V-polarized ground directional “torque†with the line’s zero-sequence impedance angle. The relay computes a torque-like quantity and decides forward if it’s positive and reverse if negative.
A good \(Z_{0L}\) maximizes the separation of forward vs reverse faults even with residual load flow, system unbalance, and CT/VT errors. An incorrect angle skews the “operating circle†and can cause misdirection near the resistive axis.
Tip: forward faults push the phasor product into +Re{·} when \(Z_{0L}\) tracks the actual line.
SELOGIC bits that supervise which ground-directional paths are allowed to run. Common examples: E32IV (enable V/I paths) and ILOP (loss-of-potential, blocks V-path when LOP blocking is enabled).
Confirm how these bits are mapped in your scheme (52a, VT health, channel status, etc.).
App convenience to save/recall your scenario (all inputs/flags/order). It does not map to an SEL-311C setting.
Blinders are auxiliary boundaries drawn on the R–X (Ω) plane to keep a distance element from “seeing†heavy load or power swings as faults. They can be vertical (constant R), angular (constant power factor), or curved (arc segments) and are used to block or gate tripping.
Heavy load moves the apparent impedance toward the +R axis (small \(X/R\)). By fencing a “no-trip†region with blinders, load encroachment and slow swings won’t enter the tripping characteristic (mho/quad).
These are UI constructs for study/visualization (not tied to any vendor logic). Use with your protection logic to block/gate trip within the fenced region.
Sets the slope of the angular blinder relative to the +R axis. A constant-PF line through the origin obeys \(X = R\tan\theta\), where \(\theta = \cos^{-1}(\mathrm{PF})\).
Sets the size of a circular arc blinder (load-magnitude fence) with \(|Z| = \rho\). This emulates a “no-trip†arc at a given apparent impedance magnitude.
For a chosen \(\theta\): \(R = \rho\cos\theta,\; X = \rho\sin\theta\). These points sit on the arc and the PF line simultaneously.
This is an in-browser distance protection (ANSI 21) study and settings-visualization tool. It plots mho and quadrilateral zones and impedance reach on the R-X (impedance) plane so you can understand and check zone settings. Everything runs locally in your browser.
Protection and system engineers, commissioning and testing teams, and students who want to visualize distance protection zone reach and check setting concepts.
This tool does not replace the relay manufacturer's setting software or a formal project distance protection study. All settings must be confirmed against the applicable standards and sound engineering judgment.
Privacy: This tool runs entirely in your browser. The values you enter are processed locally on your computer and are not uploaded to a server.