4-36 Loss-of-Potential, Load Encroachment, and Directional Element Logic Date Code 20001006
SEL-351 Instruction Manual
To accomplish this, the DIR1 setting is “turned off,” and the corresponding SELOGIC Control
Equation torque control settings for the above overcurrent elements are used to make the elements
directional (forward or reverse) or nondirectional. The required settings are:
DIR1 = N (“turned off”; see Figure 4.12, Figure 4.17, and Figure 4.18)
67P1TC = 32PF (direction forward; see Figure 3.3)
67G1TC = 32GF (direction forward; see Figure 3.10)
51PTC = 32PF (direction forward; see Figure 3.14)
51ATC = 32PR (direction reverse; see Figure 3.15)
51BTC = 32PR (direction reverse; see Figure 3.16)
51CTC = 32PR (direction reverse; see Figure 3.17)
51NTC = 1 (nondirectional; see Figure 3.18)
51GTC = 32GF (direction forward; see Figure 3.19)
This is just one example of using SELOGIC Control Equation torque control settings to make
overcurrent elements directional (forward or reverse) or nondirectional. This example discussed
only Level 1 overcurrent elements (controlled by level direction setting DIR1). The same setting
principles can apply to the other levels as well. Many variations are possible.
Courtesy of NationalSwitchgear.com
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