Schweitzer Engineering Laboratories SEL-351A - Directional Control Provided by Torque Control Settings (Not in SEL-351 A-1)

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Date Code 20080213 Instruction Manual SEL-351A Relay
Loss-of-Potential, Load Encroachment, and Directional Element Logic
Directional Control Provided by Torque Control Settings (Not in SEL-351A-1)
Directional Control Provided by Torque Control
Settings (Not in SEL-351A-1)
For most applications, the level direction settings DIR1–DIR4 are used to set
overcurrent elements direction forward, reverse, or nondirectional. Table 4.4
shows the overcurrent elements that are controlled by each level direction
setting. Note in Table 4 .4 that all the time-overcurrent elements (51_T
elements) are controlled by the DIR1 level direction setting. See Figure 4.17,
Figure 4.18, Figure 4.23, and Figure 4.24.
In most communications-assisted trip schemes, the levels are set as follows:
Level 1 overcurrent elements set direction forward (DIR1 = F)
Level 2 overcurrent elements set direction forward (DIR2 = F)
Level 3 overcurrent elements set direction reverse (DIR3 = R)
Suppose that the Level 1 overcurrent elements should be set as follows:
67P1 direction forward
67G1 direction forward
51PT direction forward
51AT direction reverse
51BT direction reverse
51CT direction reverse
51NT nondirectional
51GT direction forward
51G2T direction reverse
To accomplish this, the DIR1 setting is “turned off,” and the corresponding
SEL
OGIC 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 4.17, Figure 4.18, Figure 4.23, and
Figure 4.24)
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)
51G2TC = 32GR (direction reverse; see Figure 3.20)
This is just one example of using SEL
OGIC control equation torque control
settings to make overcurrent elements directional (forward or reverse) or
nondirectional. This example shows only Level 1 overcurrent elements
(controlled by level direction setting DIR1). The same setting principles apply
to the other levels as well. Many variations are possible.
Courtesy of NationalSwitchgear.com