metric element.
Sense faults with as much as 100,000 ohms using new incremental
conductance element (patent pending).
s
Best Choice Ground Directional Element Logic
Maintain sensitive protection for a wide range of fault currents,
even for grounding system configuration changes.
s
All Directional Ground Features in One Relay Model
Minimize expense of spare relays and engineering time by
standardizing on all applications using the same relay model.
s
High-Current Rating Neutral Channel
Realize enhanced service reliability of the sensitive neutral current
channel with a thermal rating of 500 A for one second.
New Directional Ground Protection for
Petersen Coil Grounded, Impedance
Grounded, and Ungrounded Power Systems
Major Features and Benefits
SEL provides capabilities and
settings for ALL TYPES of grounded
systems in ONE relay.
Making Electric Power Safer, More Reliable, and More Economical
N
ABC
3
3
1
Forward Fault
Ground Fault
Petersen
Coil
SEL-351
Core-Balance CT
Core-Balance CT
N
ABC
3
1
Reverse Fault
SEL-351
Ungrounded
Solid
Impedance
or
or
or
or Schweitzer Engineering Laboratories, Inc. is committed to
quality. Our certification to the ISO 9001 quality standard
and our ten-year product warranty are examples of this
commitment. We encourage and appreciate your feedback,
and we will use this information to continually improve our
products and services.
SEL-351 Directional Ground Fault Technology
Specify SEL-351 Relays with sensitive directional ground fault protection
elements for Petersen Coil grounded, impedance grounded, and
ungrounded distribution systems. A traditional wattmetric element
and a new, more sensitive incremental conductance element provide
ground fault protection for Petersen Coil grounded systems (below).
Variations of existing SEL ground fault protection technology provide a
zero-sequence reactance element for ungrounded/high-impedance
grounded systems (right) and protection for low-impedance grounded
systems.
Traditional and New Methods
AC Current Input - Neutral Channel IN
0.2 A nominal; 15 A continuous, 500 A for 1 second, linear to 5.5 A
symmetrical. 1250 A for 1 cycle.
Burden: 0.002 VA @ 0.2 A, 1.28 VA @ 15 A
Instantaneous/Definite-Time Overcurrent Element
Pickup Range - Neutral Channel IN
0.2 A nominal; 0.005 2.500 A, 0.001 A steps.
Time-Overcurrent Element Pickup Range - Neutral
Channel IN
0.2 A nominal; 0.005 0.640 A, 0.001 A steps.
2350 NE Hopkins Court Pullman, WA 99163-5603 USA
Phone: (509) 332-1890 Fax: (509) 332-7990 FaxBack: (509) 334-8293
Internet: www.selinc.com E-mail: info@selinc.com
Commitment to Quality
SEL sales representatives are prepared to assist you. Contact your
nearest sales representative, application engineer, or customer service
representative at (509) 332-1890. Visit our web site at www.selinc.com
for more information.
Copyright © SEL 2002 (All rights reserved). Printed in USA. All trademarks are the property of their respective holders.
Patents pending. Pcoilflyr 20020125
Contact Us
Specifications
Making Electric Power Safer, More Reliable, and More Economical
Zero-Sequence Impedance Plane
Forward Fault
Reverse Fault
X
0
R
0
XC
0S
-XC
OL
Petersen Coil Grounded System Protection
Ungrounded/High-Impedance Grounded
System Protection
Traditional wattmetric
element operating
characteristic.
New, more sensitive
incremental conductance
element operating
characteristic
(patent pending).
New, zero-sequence
reactance element
operating characteristic
(patent pending). B
0
(susceptance)
Reverse
Fault
Forward
Fault G
0
(conductance)
I
0
I
0
Tuned or
Overcompensated System
Undercompensated
System
I
0
I Reverse Fault
Region
0
I Forward Fault
Region
0
v
0