Date Code 20011026 Specifications 2-13
SEL-321/321-1 Instruction Manual
OTHER LOGIC
Zone 1 Extension (Z1X) Scheme Logic
This logic modifies the reach of all Zone 1 distance elements by multiplier Z1EXTM once all
three poles are closed for Z1EXTD time.
The Zone 1 reaches cannot be extended if any of the following elements are asserted:
M1P - M4P, Z1G - Z4G, 51NP, or 51QP.
All Zone 1 reaches retreat to their set reach when the programmable input assigned to CLOSE
asserts.
Settings
Zone 1 Extension Delay Z1EXTD Sets the minimum time all three breaker poles must
be closed before extending the Zone 1 reach.
Zone 1 Extension Multiplier Z1EXTM Sets the scalar by which all Zone 1 reaches are
multiplied. Never less than one.
External Input
Close Signal CLOSE Assign CLOSE to a programmable input. Drive
with the close signal to the breaker(s).
Logic Output
Extend Zone 1 Reaches Z1X When asserted, Zone 1 reaches are extended.
Supporting Drawing: Figure 2.35.
Remote-End-Just-Opened (REJO) Logic
The REJO logic accelerates tripping for one- or two-phase in-section faults without using a
communications channel. This logic generates a tripping condition, if any elements in the MTCS
variable assert and a REJO condition exists.
Settings
Coordinating Timer REJOD Delays REJO assertion to permit coordination for
out-of-section faults.
Current Detectors 3P50R Sets phase current threshold for detecting load.
Logic Outputs
Current above 3P50R threshold
in all three phases 3P50R Three-phase current is present to indicate remote
breaker is closed. This must drop out to declare
REJO.
Current above 3P50R
threshold in one phase 50P One-phase current is above the 3P50R threshold.
This must remain asserted for REJO declaration.
Remote-End-Just-Opened REJO Enables tripping by elements in the MTCS variable.
Supporting Drawing: Figure 2.36.
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