Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 400 / 706

9.44
SEL-351-5, -6, -7 Relay Instruction Manual
Date Code 20070117
Setting the Relay
Settings Explanations
The zero-sequence line impedance setting Z0MAG is automatically scaled by
the relay for use with neutral channel IN for directional control on low-
impedance grounded systems. See Z0F and Z0R settings explanation in the
latter part of
Section 4: Loss-of-Potential, Load Encroachment, and
Directional Element Logic .
Line length setting LL is unitless and corresponds to the line impedance
settings. For example, if a particular line length is 15 miles, enter the line
impedance values (
Ω
secondary) and then enter the corresponding line length:
LL = 15.00 (miles)
If this length of line is measured in kilometers rather than miles, then enter:
LL = 24.14 (kilometers)
Delta-Connected PTs (PTCONN = DELTA)
Additional zero-sequence source impedance settings Z0SMAG (magnitude,
Ω
secondary) and Z0SANG (angle, degrees) are required so that zero-sequence
voltage can be derived for fault locating.
Enable Settings
Refer to Other Enable Settings on page SET.2 and Breaker Monitor Settings
(See Breaker Monitor on page 8.2) on page SET.26 .
The enable settings on Settings Sheet 2 (E50P–ESSI) control the settings that
follow, through Sheet 17 . Enable setting EBMON on Settings Sheet 25
controls the settings that immediately follow it. This helps limit the number of
settings that need to be made.
Each setting subgroup on Settings Sheets 2 through 17 has a reference back to
the controlling enable setting. For example, the neutral ground time-
overcurrent element settings on
Sheet 7 (settings 51NP–51NRS) are controlled
by enable setting E51N.
Other System
Parameters
Refer to Power System Configuration and Date Format (See Settings
Explanations on page 9.37) on page SET.24 .
The global settings NFREQ and PHROT allow you to configure the SEL-351
to your specific system.
Set NFREQ equal to your nominal power system frequency, either 50 Hz
or 60 Hz.
Set PHROT equal to your power system phase rotation, either ABC or
ACB.
Set DATE_F to format the date displayed in relay reports and the front-
panel display. Set DATE_F to MDY to display dates in Month/Day/Year
format; set DATE_F to YMD to display dates in Year/Month/Day format.
NOTE:
If global setting VSCONN =
3V0, settings Z0SMAG and Z0SANG
are not required, regardless of the
PTCONN setting.