2-12 Relay Element Settings
Date Code 20020206 SEL-300G Instruction Manual
transformer winding and bushing phase-to-phase faults. The Zone 2 element may then be set to
reach through the step-up transformer into the system and with a longer time delay.
The relay includes a user settable SEL
OGIC Control Equation to disable the distance elements, as
well as supervision by the 60LOP loss-of-potential logic and a simple load encroachment
function to provide three-phase element security under maximum generator loading conditions.
Setting Descriptions
Enable System Backup Protection (N, D, V, C) EBUP = D
Set EBUP = D to enable phase distance elements. If system backup protection is not
required, set EBUP = N. When EBUP ¹ D, the 21P1P, 21P1T, 21P2P, and 21P2T
Relay Word bits are inactive and the relay hides the following relay settings, which do
not need to be entered. (See Voltage-Controlled/Restrained Time-Overcurrent
Elements for EBUP = V and C setting descriptions.)
Zone 1 Phase Distance Reach (OFF, 0.1 to 100.0 ohms) Z1R = 8.0
Zone 1 Phase Distance Offset (0.0 to 10.0 ohms) Z1O = 0.0
Set Z1R to define the forward (toward the system) phase distance reach, defined in
secondary ohms. Because the relay includes a load encroachment function for distance
element security under heavy load, load impedance is not a concern when selecting the
Z1R reach setting. Setting Z1R = OFF disables the element and causes the relay to
hide the balance of the settings associated with Zone 1.
The Z1O setting defines the element offset. When an SEL-300G0 or SEL-300G2
Relay is applied with current transformers as shown in Figure 5.16 or Figure 5.17, you
may wish to apply a positive offset equal to the generator impedance as backup
generator phase-to-phase fault protection.
Zone 1 Maximum Torque Angle (90 to 45 degrees) MTA1 = 88
Set MTA1 equal to the angle of the transformer plus system impedance defined by the
Zone 1 reach setting. The relay places the distance element maximum reach along a
line at the angle defined by the MTA1 setting.
Zone 1 Transformer Compensation Angle (0, -30, 30 degrees) Z1CMP = 0
Use the Z1CMP setting to compensate the phase distance element for the presence of a
delta-wye generator step-up transformer between the generator and system. When the
element is not set to reach through the step-up transformer, set Z1CMP = 0. When the
element is set to respond to phase faults on the high side of a delta-wye transformer,
and the system phase-to-neutral voltage phase angle leads the generator phase-to-
neutral voltage phase angle by 30°, set Z1CMP = -30°. When the system phase-to-
neutral voltage phase angle lags the generator phase-to-neutral voltage phase angle by
30°, set Z1CMP = 30°.
Zone 1 Phase Distance Time Delay (0.00 to 400.00 s) Z1D = 0.00
The Z1D setting defines the Zone 1 element definite-time delay.
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