272
350
Feeder Protection System
Distribution Feeder Protection
350 RELAY
TRIP
BUS
LOAD
3
1
52
CLOSE
50G/
51G
50P 50N
79
50G 51G
22
21
METERING
TRANSIENT RECORDER
EVENT RECORDER
51N51P
50_2
111
49
1
1
27P
59P 27X 59X 59_2 59N 81U 81O
CLP
50BF 79
111111
MONITORING
BUSVT
Protection Features
Multiple Options
Several option for protection &
communications are provided to match
basic to high end application requirements.
Protection
The 350 feeder protection system offers
protection, control and monitoring in one
integrated, economical and compact
package.
Timed Overcurrent (Phase, Ground,
Neutral)
The 350 has three-phase TOC elements
which enables coordination with upstream
and downstream protection devices such
as fuses, overload relays, etc to maximize
fault selectivity and minimize interruptions
and downtime.
Multiple time current curves are available
including IAC, IEC, ANSI and IEEE curves.
Additional user programmable flex curves
can be used to customize and meet
specific coordination requirements. The
TOC has both linear and instantaneous
reset timing function to coordinate with
electro-mechanical relays
Instantaneous Overcurrent (Phase,
Ground, Neutral)
The instantaneous element provides
fast clearance of high magnitude
faults to prevent damage to the power
infrastructure and the equipment
connected to it.
Enhanced Diagnostics
Preventative Maintenance
The 350 allows users to track relay exposure
to extreme environmental conditions by
monitoring and alarming at high ambient
temperatures. This data allows users to
proactively schedule regular maintenance
work and schedule upgrade activities.
The diagnostics data enables the user to
understand degradation of electronics due
to extreme conditions.
Cost Effective
Robust Design
The 350 is subjected to Accelerated
Life Testing (ALT) to validate accurate
relay function under specified normal
conditions. The device is further tested for
durability through Highly Accelerated Life
Testing (HALT) where it undergoes extreme
operating conditions. The robust 350
design ensures long term operation.
Reduced Life Cycle Cost
The 350 is designed to reduce total
installation and life cycle cost for feeder
protection. The draw out construction
of the device reduces downtime during
maintenance and decreases extra
wiring needed for relay testing and
commissioning.
Neutral Overcurrent
The neutral signal is derived as the residual
sum of the three phase CTs eliminating the
need for an additional ground sensor.
Sensitive Ground Overcurrent
Sensitive ground protection feature
detects ground faults on high impedance
grounded systems in order to limit damage
to conductors and equipment. Special
low ratio CT’s are used for this purpose to
detect low magnitude ground faults.
Over/Under Voltage Protection
Overvoltage / Undervoltage protection
features can cause a trip or generate
an alarm when the voltage exceeds a
specified voltage setting for a specified
time.
Frequency Protection
The 350 offers overfrequency and
underfrequency elements to improve
network (grid) stability using voltage
or frequency based load shedding
techniques.
It also provides back up protection when
protecting feeders and other frequency
sensitive power equipment.
Arc Flash Mitigation
The 350 relay is equipped with multiple
setting groups and two user definable
inverse curves -FlexCurves A and B for
fast and reliable arc-flash mitigation and
breaker operation. In the event of an arc-
Device
Number
Function
27P Phase Undervoltage
27X Auxiliary Undervoltage
49 Thermal Model
50P Phase Instantaneous Overcurrent
50N Neutral Instantaneous Overcurrent
50G Ground/Sensitive Ground
Instantaneous Overcurrent
50BF Breaker Failure
50_2 Negative Sequence Overcurrent
51P Phase Timed Overcurrent
51G Ground Timed Overcurrent
51N Neutral Timed Overcurrent
59P Phase Overvoltage
59X Auxiliary Overvoltage
59N Neutral Overvoltage
59_2 Negative Sequence Overvoltage
67G Ground Directional Overcurrent
67N Neutral Directional Overcurrent
79 Autoreclose
81U Underfrequency
81O Overfrequency
CLP Cold Load Pickup
ANSI Device Numbers & Functions
Latched Lockout available as a standard feature
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