Schweitzer Engineering Laboratories SEL-387E - Setting Descriptions; Operating Quantity from W1, W2 (32 IOP); Positive-Sequence Current Restraint Factor, I0;I1 (A0); REF Directional Element Enable (E32 I)

Date Code 20080110 Protection Functions 3-31
SEL-387E Instruction Manual
time overcurrent curve (curve U4) at the lowest time-dial setting (0.5) and with 50GP as the
pickup setting.
Figure 3.13: REF Protection Output (Extremely Inverse-Time O/C)
Relay Word bit 32IF (forward fault) torque controls the timing curve, and IRW3 operates the
timing function. The curve resets in one cycle if current drops below pickup or if 32IF deasserts.
When the curve times out, Relay Word bit REFP asserts. You can use this bit directly as an input
to the appropriate trip variables, TR
n , to trip the breaker or breakers that feed the fault.
Setting Descriptions
REF Directional Element Enable (E32I)
Range:
SELOGIC
®
control equation
The setting E32I is a SEL
OGIC control equation setting that uses Relay Word bits to define the
conditions under which the relay will enable REF. A logical state of 1 for this control equation
enables the other REF settings and satisfies one of the conditions the REF element needs to
activate. A logical state of 0 for this control equation disables the other REF settings; the relay
hides these settings, and they are unavailable for use.
Operating Quantity from W1, W2 (32IOP)
Range:
1, 2, 12
The setting 32IOP tells the relay which winding or combination of windings it should use in
calculating residual current, which acts as the Operate quantity for the directional element.
Positive-Sequence Current Restraint Factor, I0/I1 (a0)
Range:
0.02–0.50, in 0.01 steps