Sel 411L - Figure 3.174 Table Y12. Summary of the Valpha and 81 UVSP Calculations

P.3.260
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
Undervoltage Supervision Logic
Set 81UVSP to 60 percent of this value:
Equation 3.104
Equation 3.105
Table 3.58 summarizes the results of the three cases.
Settings Descriptions
E81 (Enable 81 Elements)
Set E81 to enable as many as six over/underfrequency elements. When
E81 = N, the relay disables the frequency elements and hides corresponding
settings.
81UVSP (81 Element Undervoltage Supervision)
This setting applies to all six frequency elements. If the positive-sequence
voltage falls below the 81UVSP setting, all frequency elements are disabled.
81DnP (Level n Pickup)
Set the value at which you want the frequency element for each of six levels to
assert. For a value of 81DnP less than the nominal system frequency NFREQ
(50 or 60 Hz), the element operates as an underfrequency element. For a value
greater than NFREQ, the element operates as an overfrequency element. Note
that n can be one of six levels (1–6).
81DnD (Level n Time Delay)
Select a time, in seconds, for which you want frequency elements to wait
before asserting.
Figure 3.174 Table Y12. Summary of the Valpha and 81UVSP Calculations
Case PT Connections VA VB VC Valpha 0.6 • Valpha
Case 1 Three-phase 67 0° 67 –120° 67 0° 142.13 85.28
Case 2 Single-phase, VA 67 0° 0 0 94.75 56.85
Case 3 Single-phase, VB/VC 0 67 –120° 0 47.38 28.43
81UVSP 0.6 47.37 V=
81UVSP 28.43 V=
Setting Prompt Range Default Category
E81 Enable frequency elements (N, 1–6) N, 1–6 N Group
Setting Prompt Range Default Category
81UVSP 81 element undervoltage super
(20.00–200 V, s)
20.00–200 85 Group
Setting Prompt Range Default Category
81DnPn = 1–6 Level n Pickup (Hz) 40.01–69.99 61.00 Group
Setting Prompt Range Default Category
81DnD
n = 1–6
Level n time delay (0.04–400 s) 0.04–400.00 2 Group