Date Code 20010625 Application Settings for SEL-311L Relays 14-1
SEL-311L Instruction Manual
SECTION 14: APPLICATION SETTINGS FOR SEL-311L
RELAYS
INTRODUCTION
Application Settings in the SEL-311L Relay reduce the number of settings for users who do not
require all of the relay features. Some functions are disabled and their settings hidden, while
others are reduced in scope and complexity (e.g., one overcurrent element rather than four).
APPLICATION SETTING 87L—DIFFERENTIAL PROTECTION WITH OVERCURRENT
BACKUP
Set APP = 87L in the SEL-311L to configure the relay for differential protection with two
backup phase-overcurrent and two ground-overcurrent elements (50P1T/51PT/50G1T/51GT).
These elements operate only if differential protection is disabled by communications channel
failure. No potentials are required by the relay in this application.
When APP = 87L, the SEL-311L:
1. Configures itself as full-function differential relay. All differential and tapped load
settings are available.
2. Enables two phase-overcurrent and two ground-overcurrent elements:
• 50P—instantaneous/definite-time phase-overcurrent element (E50P = 1)
• 50G—instantaneous/definite-time ground-overcurrent element (E50G = 1)
• 51P—inverse-time phase-overcurrent element (E51P = Y)
• 51G—inverse-time ground-overcurrent element (E51G = Y)
3. Hides settings for:
• Polarizing (IPOL) CT Ratio (CTRP)
• Phase (VA, VB, VC) PT Ratio (PTR)
• Synchronism Voltage (VS) PT Ratio (PTRS)
• Positive-Sequence Line Impedance Magnitude (Z1MAG)
• Positive-Sequence Line Impedance Angle (Z1ANG)
• Zero-Sequence Line Impedance Magnitude (Z0MAG)
• Zero-Sequence Line Impedance Angle (Z0ANG)
• Line Length (LL)
• Directional control (E32 = AUTO)
• SEL
OGIC
®
variables (ESV = 1)
• SEL
OGIC Display points (EDP = 3)
• Demand metering (EDEM = THM)
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