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I.L. 40-201.9
For Example:
If the reverse reach has been determined to be 15 ohms at 75°, set Z3GR = 15.
7.10
Zone 3 ground unit timer (T3G)
Selects the time delay for Zone 3 Ground fault detection in seconds. Set T3G = 0.30 if the min-
imum time delay for step distance coordination is 300 milliseconds.
8.
OUT OF STEP LOGIC SETTINGS.
Phase comparison system is immune to system swings. When voltage inputs are part of the
REL 352, blinders are provided for power swing detection. The Out of Step Trip (OST) logic is
executed all the time regardless of the status of the channel. This means that OST is possible
when the system is operating the phase comparison algorithm only. The Out of Step Block
(OSB) logic is only applicable to the back-up system, i.e., Zone 2 and Zone 3.
8.1
Out of Step Trip (0ST)
This setting enables the Out of Step Trip logic. Set the relay to:
OUT:
WAYI:
WAYO:
8.2
Out of Step Block (OSB)
This setting enables the Out of Step Block logic that blocks the Zone 2 and/or Zone 3 distance
units under Out of Step Conditions.
Chose:
OUT:
Z2:
Z3:
BOTH:
8.3
Inner blinder, 21 BI, setting. (RT)
This setting is the offset in the perpendicular direction to the line impedance on the R-X diagram
in Ohms.
For Example:
Set RT = 4.0 ohms for an inner blinder 4 ohms away from the line impedance.
NOTE:
5-10
If there is no need for an Out of Step Trip.
If the controlled Out of Step Trip is in the Way in to the operating characteristics of
the relay.
If the controlled Out of Step Trip is in the Way out of the operating characteristics of
the relay.
If no OSB is required
If only Zone 2 units are to be blocked by the OSB logic on Out of Step conditions.
If only Zone 3 units are to be blocked by the OSB logic on Out of Step conditions.
If both Zone 2 and Zone 3 are to be blocked by the OSB logic on Out of Step condi-
tions.
RT restricts tripping inside its operating characteristics. It may be used for load
restriction purposes to avoid tripping under load.
Power Automation and Protection Division
REL 352 Version 1.00
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