Sel SEL-FT50 User manual

Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
SEL-FT50/SEL-FR12 Fault Transmitter and Receiver SystemInstruction Manual
Accelerate Tripping, Speed Up Restoration,
and Improve Safety on Distribution Feeders
SEL-RP50 not available in all regions need new photo
Major Features and Benefits
The SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System speeds up distribution-protection schemes by
detecting and transmitting distribution feeder fault information to recloser controls or relays. Install the SEL-FT50
Fault Transmitters on laterals, branches, and the main line to broadcast fault status to one or more SEL-FR12 Fault
Receivers. The SEL-FR12 communicates the fault data through MIRRORED BITS®communications to a relay or
recloser control within 6 ms.
➤Real-Time Distribution Fault Detection. Identify the faulted line segment with fault detection and low-
latency communication while a fault is still active; for use in protection schemes.
➤Enhanced Protection. Make real-time changes to the protection strategy based on information from the faulted
distribution-line segment.
➤Improved Selectivity. Trip a main feeder or branch recloser only when necessary. Avoid unnecessary entire-
feeder outages.
➤Customized Reclosing Strategies. Block or enable reclosing for specific line segments.
➤Improved Power Quality, Reduced System Stress, Limited Equipment Damage, and Enhanced Safety.
Leverage faulted feeder status to better coordinate between protective elements, leading to faster trip times.
➤Easy Operation. Configure the fault transmitters and receiver without additional software.
➤SEL-RP50 Fault Repeaters facilitate SEL-FT50 installations in locations where line-of-sight might be
obscured by terrain, trees, or buildings.
➤No Batteries. Power the SEL-FT50 and SEL-RP50 directly from line current.
SEL-FT50/SEL-FR12
Fault Transmitter and Receiver System

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Functional Overview
➤Easy Installation. Install the SEL-FT50 and SEL-RP50 on live lines by using familiar line tools and
techniques.
➤Flexible Integration. Install the SEL-FT50/SEL-FR12 system in an existing relay protection system.
Functional Overview
Figure 1 SEL-FT50, SEL-RP50, and SEL-FR12 System Overview -- need updated drawing

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Functional Overview
The SEL-FT50 and SEL-FR12 contain subsystems outlined in the upper and
lower portion of Figure 1, respectively.
The SEL-RP50, outlined in the center portion of Figure 1, is available in certain
markets. Installing one or more SEL-RP50s per SEL-FT50 can mitigate obstruc-
tions that otherwise compromise the radio path.
The SEL-FT50/SEL-FR12 system consists of as many as 12 SEL-FT50 Fault
Transmitters and 1 SEL-FR12 Fault Receiver. The SEL-FT50 is mounted on dis-
tribution conductors with voltages as high as 38 kV. The SEL-FR12 is mounted
in a recloser control cabinet or in a substation control house.
When one or more SEL-FT50 Fault Transmitters detect a fault, they send a wire-
less signal to the SEL-FR12. The SEL-FR12 transfers the received signal to the
recloser control or relay via MIRRORED BITS communications in as little as 6 ms.
The recloser control uses the fault information to make protection or relay deci-
sions.
To monitor the health of the system, the SEL-FT50 Fault Transmitters periodi-
cally send communication link-check messages to the SEL-FR12 to indicate their
status.
Each SEL-RP50 Fault Repeater forwards fault and link messages from one
SEL-FT50. Up to five SEL-RP50s can be installed in a row with proper settings,
and must be installed on the same phase conductor for proper operation in low
current conditions. The SEL-RP50s will usually be installed in sets of three, one
per phase.
The SEL-FR12 recognizes messages coming directly from SEL-RP50s and/or
indirectly via SEL-RP50s.
NOTE: Systems with SEL-FT50s
manufactured before May 2021 only
support one SEL-RP50 per SEL-FT50.
See
Appendix D: SEL-RP50 Fault
Repeater Detailed Implementation on
page 54
for required settings.

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
System Overview
System Overview
Figure 2 provides an overview of the SEL-FT50/SEL-FR12 system and illus-
trates how to apply it across a distribution power system.
The SEL-FT50/SEL-FR12 system components are easy to use, and they contain
many powerful and innovative features. Use programmable logic in the
SEL-651R or in connected relays to incorporate the new protection capabilities
and achieve the benefits shown in Figure 2.
Figure 3 depicts the key components of the FT50-0001/FT50-0003/FT50-0005/
FT50-0006 models. The other product variants FT50-0004/FT50-0007 have
identical interior features and similar exterior features.
Figure 2 SEL-FT50/SEL-FR12 System -- need updated drawing
NOTE: The SEL-RP50 is not available
in all markets. See
Tab le 13 .
Figure 3 SEL-FT50 Overview
Shotgun stick loop
Current transformer
Twistlock housing
for setting access
Omnidirectional antenna for
the radio transmitter
Left control (DIP)
switch bank
SW 1–4 Unit ID
SW 5–8 Network ID
Right control (DIP)
switch bank
SW 6–8 fault pickup
Conductor stop
Spring for secure installation

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
System Overview
Each SEL-FT50 mounts onto and monitors the line current on one phase. When a
fault occurs, the SEL-FT50 transmits a high-speed wireless signal to influence
protection decisions. Control (DIP) switches inside the transmitter allow easy
selection of unit and Network IDs. No batteries are needed because the
SEL-FT50 is powered by line current.
In applications where trees, buildings, or terrain could block the line-of-sight
path between the SEL-FT50 and SEL-FR12 antenna, one or more SEL-RP50
Fault Repeaters can be installed to forward signals that might otherwise be
blocked. Figure 4 shows the exterior and interior features of the SEL-RP50.
Each SEL-RP50 mounts onto and harvests energy from one phase. The
SEL-RP50 Unit ID and Network ID DIP switch selections must be set the same
as the companion SEL-FT50 or SEL-RP50s, and mounted on the same electrical
phase. Like the SEL-FT50, for three-phase systems the SEL-RP50s will normally
be installed in groups of three. Up to five SEL-RP50 (sites) may be used for each
SEL-FT50 with appropriate Repeater ID selections. See Technical Support on
page 57 for details and examples on SEL-RP50 deployment. No batteries are
needed because the SEL-RP50 is powered by line current. Each SEL-RP50 site
typically adds up to 1 ms to the fault response time as seen by the SEL-FR12.
Figure 4 SEL-RP50 Overview
Shotgun stick loop
Current transformer
Twistlock housing
for setting access
Omnidirectional antenna for
the radio receiver and transmitter
Left control (DIP)
switch bank
SW 1–4 Unit ID
SW 5–8 Network ID
Right control (DIP)
switch bank
SW 1–3 Repeater ID
Conductor stop
Spring for secure installation
NOTE: The SEL-RP50 is a node in
the wireless link between the
SEL-FT50 and the SEL-FR12. The
SEL-RP50 receives fault and link
messages, modifies the message by
attaching identifier and diagnostic
data, then transmits this message to
the next device in the link (e.g.,
another SEL-RP50 or SEL-FR12).

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
System Overview
The SEL-FR12 collects wireless signals simultaneously from as many as 12
SEL-FT50 Fault Transmitters (enough for 4 three-phase installations). The
SEL-FR12 reports faults to a relay or recloser control in less than 6 ms via
MIRRORED BITS. The SEL-FR12 HMI contains 29 LEDs and 1 pushbutton, as
shown in Figure 5.
➤The ENABLED LED illuminates green when the SEL-FR12 is turned
on and operational. The ENABLED LED flashes when the SEL-FR12 is
in one of the diagnostic modes listed.
➤The 12 FAULT LEDs (red, one per Unit ID) illuminate after the
SEL-FR12 receives a Fault message from the associated SEL-FT50.
These LEDs have a latching behavior so that once set, they remain on
until reset by the TARGET RESET pushbutton or via MIRRORED BITS
command.
➤The 12 LINK LEDs (green, one per Unit ID) have a tristate operation:
➢LINK LEDs are initially off when the SEL-FR12 is turned on or
after it receives a clear link status command via MIRRORED BITS.
➢LINK LEDs illuminate when the SEL-FR12 receives consecutive
Link messages or one Fault message from the associated
SEL-FT50. These LEDs have a delayed dropout behavior. Once
illuminated, they remain illuminated as long as Link signals are
periodically received.
➢LINK LEDs begin to flash after one minute elapses without
receipt of a Link message for the associated Unit ID. When Link
or Fault signals resume, the LINK LED stops flashing and stays
illuminated once again.
Figure 5 SEL-FR12 Overview
ENABLED
LED
FAULT and LINK
status LEDs
MIRRORED BITS
status LEDs
TARGET RESET
pushbutton
Serial port
(DB-9 connector)
Power supply
input (9–30 Vdc)
Control (DIP) switches to select:
• Network ID—SW 1–4
• Baud rate—SW 5–6
• MIRRORED BITS TX and RX ID—SW 7–10
• Near/distant SEL-FT50—SW 11–14
Radio antenna
BNC connector
Grounding lug
NOTE: The ENABLED LED operation
changes during diagnostic modes (see
Receive Signal Strength Indicator on
page 26
and Read Settings on
page 30
).
NOTE: The SEL-FR12 works
identically with systems that include
SEL-RP50s.

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Application Examples
➤The ROK, TX, RX (green), and LOOP (red) LEDs indicate MIRRORED
BITS status and activity. The ROK LED illuminates when MIRRORED
BITS data exchange is successful.
➤The TARGET RESET pushbutton resets the FAULT LEDs. Press and hold
the pushbutton to illuminate all HMI LEDs (lamp test function).
Application Examples
Collect Fault Information From Remote Branches
A traditional recloser control or substation circuit breaker must be coordinated
with the other protective devices on a distribution feeder, including fuses on
downstream line segments. On the sample feeder in Figure 6, the recloser control
or substation relay cannot distinguish one segment from another.
The SEL-FT50/SEL-FR12 system offers increased visibility to a recloser control
by providing fault status from locations up to 400 m (0.25 miles) with line-of-
sight. Figure 7 illustrates how this allows the recloser control to see faults on
individual branches, including locations where it is not economically feasible to
install a relay or recloser. Each SEL-FT50 label in Figure 7 represents three
SEL-FT50 Fault Transmitters, one per phase.
Table 1 Target and Status LED Definitionsa
aThe FAULT and LINK LED operation changes during RSSI measurement mode and Read Settings mode (see
Receive Signal Strength Indicator on
page 26
and Read Settings on page 30 ).
LED (Color) Off Flashing On Reset Methods
FAULT (red) target No fault signal has been
received from the corre-
sponding Unit ID since the
last reset.
Not applicable. The SEL-FR12 received a
fault signal from the corre-
sponding Unit ID since the
last reset.
Manual—resets via the
TARGET RESET pushbutton.
Remote—resets via
MIRRORED BITS.
LINK (green) status The SEL-FR12 has not
detected an SEL-FT50
with the corresponding
Unit ID since initialization.
This learning feature keeps
unused LINK LEDs turned
off.
The SEL-FR12 is not pres-
ently receiving signals
from the previously learned
Unit ID, indicating that an
SEL-FT50 is not harvest-
ing energy during low-
current conditions or an
outage.
The SEL-FR12 has
received signals from the
corresponding Unit ID
within the last minute, indi-
cating that the SEL-FT50
is receiving minimum radio
link active current.
Automatic—learning mode
resets automatically after
the SEL-FR12 turns on.
Remote—resets via
MIRRORED BITS.
Figure 6 Typical Recloser Visibility
R?
?
??

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Application Examples
Each SEL-FT50 monitors line current and instantly transmits a wireless signal
when an overcurrent (fault) condition occurs. The companion SEL-FR12 receives
and aggregates fault data from as many as 12 SEL-FT50 Fault Transmitters.
Upon detecting a fault indication signal, the SEL-FR12 communicates the fault
information to the host SEL-651R recloser control, or other SEL protective relay,
by using MIRRORED BITS communications.
The SEL-FT50/SEL-FR12 system allows the protective relay or recloser control
to make intelligent decisions by using high-speed fault information from remote
locations.
Improve Fuse Coordination
In a radial distribution system, there are two main schemes that control fuse coor-
dination: fuse-saving and fuse-blowing (also called trip-saving). Each of these
schemes has shortcomings that you can address with the SEL-FT50/SEL-FR12
system.
Figure 7 Recloser Communication With Fault Transmitters
R
Wireless
SEL-FT50
SEL-FT50
SEL-FT50
SEL-FT50
SEL-FR12
SEL-651R-2

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Application Examples
Figure 8 gives a representation of a typical time-overcurrent coordination graph.
Fuse-Blowing Scheme Shortcomings
For a radial distribution system, the goal of the fuse-blowing scheme is to mini-
mize the number of customers exposed to an interruption. The scheme accom-
plishes this by allowing a fuse to clear a given fault. The recloser only trips for
faults that are not protected by a fuse. This scheme is sometimes called a trip-sav-
ing or fuse-blowing scheme because the recloser only trips when absolutely nec-
essary.
Refer to Figure 8 for the recloser control time-overcurrent element slow curve
(shown in red). This curve must coordinate with the highest-rated fuse size pres-
ent on the system, which is shown in green. An intentional coordination margin
allows for prefault load and variances in fuse construction.
For faults on sections of the feeder that are not fuse-protected, the recloser must
still implement this intentional coordination margin. The recloser control cannot
determine which downstream branch the fault is on and assumes that the fault
will be cleared by a fuse. Figure 9 shows an example of a main line feeder and a
fused lateral without a fuse. For a fault on the main line, the recloser control will
wait before using the slow curve to clear the fault (see Figure 8). For a fault on
the main line, the recloser control delays tripping unnecessarily because there is
no fuse present.
Figure 8 Example Time-Overcurrent Element Coordination
Recloser Control
Fast Curve
Recloser Control
Slow Curve
Fuse-Melting Curve
Fuse-Clearing Curve
0.01
0.1
1
10
100
100
Current (A)
1,000
1,000
Time (s)

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Application Examples
Improve Fuse-Blowing Schemes With the Fault Transmitter and Receiver
System
With the SEL-FT50/SEL-FR12 system installed as shown in Figure 10, the
recloser control receives an indication whenever a fault is on the unfused branch.
With this information, if a fault occurs on the unfused line section, the recloser
control can trip instantaneously instead of waiting for the fuse delay.
In Figure 10, the unfused tap is monitored by a set of SEL-FT50 Fault Transmit-
ters (one for each phase), one SEL-FR12, and one SEL-651R. The SEL-FR12 is
connected to the SEL-651R via a serial port.
When using the SEL-FT50/SEL-FR12 system, the SEL-651R knows when a
fault occurs on the unfused tap because one or more of the SEL-FT50 Fault
Transmitters detect the fault current and send the fault status to the SEL-FR12,
which then conveys the information to the recloser control.
The SEL-651R settings replace or modify the curve behavior while the fault is
happening. In the example fault shown in Figure 10, the recloser control enables
the recloser control fast curve (see Figure 8). Compare this to when a fault is on
the same unfused line section but the recloser control does not know it. The
recloser trips after a delay. Based on the coordination curves in Figure 8, for a
1000 A fault, using the SEL-FT50/SEL-FR12 system to trip on the fast curve
instead of the slow curve reduces the fault clearing time by 400 ms.
Fuse-Saving Combined With Fuse-Blowing Schemes
The fundamental choice in distribution-line protection is between fuse-saving
and fuse-blowing. For a given fault, designers either favor blowing fuses and dis-
rupting as few customers as possible, or tripping the recloser and interrupting the
fault without blowing any fuses. Each method has its advantages, but the protec-
tion planner has to pick one or the other.
Using the SEL-FT50/SEL-FR12 system, design smart protection that switches
from fuse-saving to fuse-blowing, or vice versa without interruption. You get the
fuse-saving or fuse-blowing benefits you want while eliminating any drawbacks.
Figure 9 Fault on Unfused Tap
R
Figure 10 SEL-FT50 on Unfused Tap
R
SEL-FR12
SEL-651R-2
When the fault is on the unfused branch, the recloser trips without fuse-coordination delay.
SEL-FT50

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Application Examples
The following two example applications show how a single protective zone using
the SEL-FT50/SEL-FR12 system allows both fuse-saving and fuse-blowing
schemes in service.
Example 1: Switchover Without Interruption From a Fuse-Blowing
Scheme to a Fuse-Saving Scheme
In this switchover scheme, utilities have the option to tailor protection for specific
line segments with different characteristics. If the SEL-FT50 declares that a fault
is present on a candidate line section, the scheme enables fuse-saving while the
fault is in progress. For other faulted line segments, the fuse-blowing scheme
works as intended.
Example 2: Switchover Without Interruption From a Fuse-Saving
Scheme to a Fuse-Blowing Scheme
In this switchover scheme, the SEL-FT50/SEL-FR12 system is used to indicate
which line section contains a fault. However, the fuse-saving scheme is the
default operating mode. When the SEL-FT50 declares that a fault is present on a
candidate line section, the scheme enables fuse-blowing while the fault is in
progress. For other faulted line segments, the fuse-saving scheme works as
intended.
Improve Feeder Cable First-Span Protection
The SEL-FT50/SEL-FR12 system improves first-span feeder cable protection.
Feeder cables are often used for substation egress, eliminating overhead line clut-
ter and improving working safety. These feeder cables radiate from a substation,
continuing for a few feet to one mile. These cables are usually terminated on a
riser pole and then connected to the overhead conductors.
To protect cable sections, some utilities use instantaneous overcurrent elements
with pickup levels set to cover the entire cable length, plus some margin that
overreaches onto a portion of the overhead line. In these applications, a high-cur-
rent fault causes an instantaneous trip with no reclosing permitted.
While this approach protects equipment, it also often causes an unnecessary per-
manent outage when the fault is on the portion of the overhead line where avail-
able fault levels are still very high. The majority of overhead faults are caused by
temporary events and are far more likely to occur than underground faults. By not
reclosing for close-in overhead faults, the entire feeder suffers a permanent out-
age that could have been avoided.
To improve the first-span feeder cable protection, use a set of three SEL-FT50
Fault Transmitters to monitor the first span of overhead line, as shown in
Figure 11. When an overhead fault occurs, the relay instantaneous element trips
the recloser or feeder breaker, but reclosing is allowed when the SEL-FT50 sig-
nals that the fault is on the overhead portion of the feeder. This simple modifica-
tion of an existing scheme improves system availability. This application extends
to any line that transitions between overhead and underground lines. Knowing
whether a fault is on an overhead or underground section of a feeder helps when
coordinating reclosing and protection schemes.

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Application Examples
Implement a Low-Cost Fast Bus-Tripping Scheme
A fast bus-tripping scheme uses a short-time delayed overcurrent element in the
bus relay to provide a quick response to bus faults. To maintain coordination for
feeder faults, the scheme must block this fast element operation whenever a
feeder relay or recloser control is picked up and timing. Traditional fast bus-trip
schemes use a hardwired control circuit or communications link to allow each
feeder relay to drive a bus relay block signal when a fault occurs on a distribution
line outside the substation.
In stations without bus differential or a fast bus-tripping scheme, a bus fault has a
long duration because the bus relay only uses a time-overcurrent element coordi-
nated with the feeder protection.
In some substations, installing a fast bus-trip scheme is not feasible because the
feeder pickup-based block signal cannot be created or transmitted through nor-
mal means. For example, some feeder protection devices (reclosers or relays)
may not be able to provide a block signal, or the device may be located far across
a substation yard, requiring a costly cable or fiber run to bring a block signal back
to the bus relay panel. Figure 12 shows a substation one-line diagram with a
recloser on each feeder. Retrofitting a traditional fast bus-tripping scheme to this
type of substation might be expensive.
Instead of installing wiring or upgrading equipment, use the SEL-FT50/
SEL-FR12 Fault Transmitter and Receiver System to bring in the required feeder
pickup signal without making changes to the medium voltage system.
In Figure 12, each feeder (A through D) is equipped with SEL-FT50 transmitters.
An example fault F1 on Feeder D triggers one or more of the SEL-FT50 transmit-
ters to transmit. The SEL-FR12 receives the transmission and immediately sends
the fault status to the bus relay. At the same time, the bus relay is also picked-up
and timing the respective definite-time overcurrent element. As soon as the
SEL-FR12 fault signal arrives, the bus relay blocks the respective definite-time
overcurrent element and maintains the block state until the overcurrent element
has completely reset. The Feeder Recloser D operates as needed to clear the fault
or lockout the line.
For a bus fault F2, none of the SEL-FT50 transmitters trigger for fault current,
and the bus relay receives no fault signal from the SEL-FR12. In this situation,
the bus relay fast-acting definite-time overcurrent element times out and trips the
bus breaker after a brief coordination delay.
Figure 11 Feeder Cable Egress Protection With Enhancements
SEL-FR12
Relay
Breaker
Substation bus
Substation
Underground
feeder cable
Wireless
Riser pole Overhead conductor
SEL-FT50

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Application Examples
You can find further details in Low-Cost Fast Bus Tripping Scheme Using High-
Speed Wireless Protection Sensors (presented at WPRC, October 2018) and SEL
application guide Using the SEL-FT50/SEL-FR12 System to Selectively Block
Fuse-Saving and Accelerated Tripping in the SEL-351R Recloser Control
(AG2018-14), both available at selinc.com.
Tripping the Right Recloser Faster
You can protect a distribution feeder with multiple reclosers. In a radial system,
to optimize selectivity, users want the recloser closest to the fault to operate for
that fault. For this reason, reclosers at the end of the distribution line are set to
trip first and the close-in reclosers are set to delay their tripping.
Figure 13 shows a fault in Zone R1. In a conventional protection design, assum-
ing the reclosers use a fuse-blowing scheme, R1 clears this fault, but only after it
gives Zones R2, R3, and R4 a chance to operate. This situation results in a long
fault duration that stresses the system and impacts the power quality on other
substation loads.
Fix this problem by using an SEL-FT50/SEL-FR12 system. In Figure 13, the
SEL-FT50 detects the fault and immediately transmits the information to the
SEL-FR12, which then sends this information to the recloser control at R1.
Because R1 knows that the fault is in its zone, it trips without waiting for the
downstream reclosers, avoiding the unnecessary coordination delay.
Figure 12 Wireless Fast Bus-Tripping Scheme
SEL-FT50
SEL-FR12
SEL-FT50 SEL-FT50 SEL-FT50
Bus Relay
F2
F1
Bus
R2R1 R3 R4
Figure 13 Radial Distribution Line With Multiple Reclosers
R1
SEL-FR12
SEL-651R-2
R2 R3 R4
SEL-FT50

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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Safety Information
Safety Information
Regulatory Information
The SEL-FT50 and SEL-RP50 are approved for use only with specific output
power configurations that have been tested and approved. Changes or modifica-
tions to the SEL-FT50, SEL-RP50, SEL-FR12, or the antenna system, and the
power output not expressly approved by the manufacturer could void the user's
authority to operate the equipment.r The radio equipment described in this man-
ual emits radio frequency energy. Professional installation is required.
United States (FCC)
This equipment has been tested and found to comply with the limits for Class A
digital devices, pursuant to FCC Part 15 Rules. Operation is subject to the follow-
ing two conditions: (1) This device may not cause harmful interference, and (2)
this device must accept any interference received, including interference that may
cause undesired operation. These limits are designed to provide reasonable pro-
tection against harmful interference when the equipment is operated in a com-
mercial environment. This equipment generates, uses, and radiates radio
frequency energy, and if not installed and used in accordance with the instruction
manual, may cause harmful interference to radio communication. Operation of
this equipment in a residential environment is likely to cause harmful interfer-
ence, in which case the user will be required to correct the interference at his/her
own expense.
Brazil
Este equipamento não tem direito à proteção contra interferência prejudicial e
não pode causar interferência em sistemas devidamente autorizados.
Este produto não é apropriado para uso em ambientes domésticos, pois poderá
causar interferências eletromagnéticas que obrigam o usuário a tomar medidas
necessárias para minimizar estas interferências.
Canada
DANGER
Install fault transmitters and
sensors in accordance with
normal safe operating
procedures. These instructions
are not intended to replace or
supersede existing safety or
operating requirements. Only
trained qualified personnel with
knowledge of high voltage
safety should install or operate
fault transmitters.
CAUTION
Although the power level is low,
concentrated energy from a
directional antenna may pose a
health hazard. Do not allow
users to come closer than 23 cm
(9 in) to the transmitter when it
is operating.
DANGER
To ensure proper safety and
operation, the equipment
ratings, installation instructions,
and operating instructions must
be checked before
commissioning or maintenance
of the equipment. The integrity
of any protective conductor
connection must be checked
before carrying out any other
actions. It is the responsibility of
the user to ensure that the
equipment is installed, operated,
and used for its intended
function in the manner specified
in this manual. If misused, any
safety protection provided by
the equipment may be impaired.
This device complies with Industry Canada
license-exempt RSS standard(s). Operation is
subject to the following two conditions: (1)
this device may not cause interference, and
(2) this device must accept any interference,
including interference that may cause unde-
sired operation of the device.
Radio apparatus shall comply with the
requirements to include required notices or
statements to the user of equipment with each
unit of equipment model offered for sale.
Le présent appareil est conforme aux CNR
d'Industrie Canada applicables aux appareils
radio exempts de licence. L'exploitation est
autorisée aux deux conditions suivantes : (1)
l'appareil ne doit pas produire de brouillage ;
(2) l'utilisateur de l'appareil doit accepter tout
brouillage radioélectrique subi, même si le
brouillage est susceptible d'en compromettre
le fonctionnement.
Les appareils radio doivent inclure les avis ou
les déclarations à l'utilisateur de l'équipement
avec chaque unité mise en vente.

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Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Safety Information
Dangers, Warnings, and Cautions
This manual uses three kinds of hazard statements, defined as follows:
Safety Symbols
The following symbols apply to this device.
Safety Marks
The following statements apply to this device.
DANGER
Indicates an imminently hazardous situation that, if
not avoided, will result in death or serious injury.
WARNING
Indicates a potentially hazardous situation that, if
not avoided, could result in death or serious injury.
CAUTION
Indicates a potentially hazardous situation that, if
not avoided, may result in minor or moderate injury
or equipment damage.
CAUTION
Refer to accompanying documents.
ATTENTION
Se reporter à la documentation.
Protective earth (ground) Terre de protection
Direct current Courant continu
Instruction manual Manuel d’instructions
DANGER
Disconnect or de-energize all external connections before opening this
device. Contact with hazardous voltages and currents inside this
device can cause electrical shock resulting in injury or death.
DANGER
Débrancher tous les raccordements externes avant d’ouvrir cet appa-
reil. Tout contact avec des tensions ou courants internes à l’appareil
peut causer un choc électrique pouvant entraîner des blessures ou la
mort.
DANGER
Contact with instrument terminals can cause electrical shock that can
result in injury or death.
DANGER
Tout contact avec les bornes de l’appareil peut causer un choc élec-
trique pouvant entraîner des blessures ou la mort.
WARNING
Use of this equipment in a manner other than specified in this manual
can impair operator safety safeguards provided by this equipment.
AVERTISSEMENT
L’utilisation de cet appareil suivant des procédures différentes de
celles indiquées dans ce manuel peut désarmer les dispositifs de pro-
tection d’opérateur normalement actifs sur cet équipement.
WARNING
Have only qualified personnel service this equipment. If you are not
qualified to service this equipment, you can injure yourself or others,
or cause equipment damage.
AVERTISSEMENT
Seules des personnes qualifiées peuvent travailler sur cet appareil. Si
vous n’êtes pas qualifiés pour ce travail, vous pourriez vous blesser
avec d’autres personnes ou endommager l’équipement.

16
SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Network Deployment Overview
Network Deployment Overview
The deployment process for the SEL-FT50 and SEL-FR12 networks consists of
the following three phases:
➤Research
➢Installation site candidate selection
➢Antenna selection
➢Link budget estimation
➤Planning
➢Path study
➢Area coverage study
➢Channel selection
➤Installation
➢SEL-FR12 installation
➢SEL-FR12 commissioning
➢SEL-FT50 installation
➢SEL-FT50 commissioning
➢Optional SEL-RP50 installation
➢Optional SEL-RP50 commissioning
Begin the network deployment process with the research and planning phases to
determine whether a reliable link can be established. If so, install and set up the
SEL-FR12 first so the SEL-FT50 devices join the SEL-FR12 network upon
installation. Consider the following guidelines before deploying an SEL-FT50/
SEL-FR12 system:
➤Select SEL-FR12 and SEL-FT50 installation locations with a clear
line of sight (i.e., minimal path obstructions) for best network perfor-
mance.
➤When obstructions limit line-of-sight, consider including SEL-RP50s
in the design. See Appendix D: SEL-RP50 Fault Repeater Detailed
Implementation on page 54.
➤Perform a separate link budget estimation for every unique link on
the network (i.e., between the SEL-FR12 and each trio of collocated
SEL-FT50 devices, the link between SEL-FT50s and corresponding
SEL-RP50s, between sequential SEL-RP50 installations, and
between the SEL-RP50 and SEL-FR12.). See Appendix C: Link Bud-
get Analysis on page 48 for more information. See Appendix D:
SEL-RP50 Fault Repeater Detailed Implementation on page 54 when
considering the use of SEL-RP50 Fault Repeaters.
WARNING
Do not perform any procedures or adjustments that this instruction
manual does not describe.
AVERTISSEMENT
Ne pas appliquer une procédure ou un ajustement qui n’est pas décrit
explicitement dans ce manuel d’instruction.
CAUTION
Equipment components are sensitive to electrostatic discharge (ESD).
Undetectable permanent damage can result if you do not use proper
ESD procedures. Ground yourself, your work surface, and this equip-
ment before removing any cover from this equipment. If your facility is
not equipped to work with these components, contact SEL about
returning this device and related SEL equipment for service.
ATTENTION
Les composants de cet équipement sont sensibles aux décharges élec-
trostatiques (DES). Des dommages permanents non-décelables
peuvent résulter de l’absence de précautions contre les DES. Raccor-
dez-vous correctement à la terre, ainsi que la surface de travail et
l’appareil avant d’en retirer un panneau. Si vous n’êtes pas équipés
pour travailler avec ce type de composants, contacter SEL afin de
retourner l’appareil pour un service en usine.

17
Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Network Deployment Overview
Research
The first step in the deployment process is to identify possible installation sites
for both the SEL-FR12 and SEL-FT50 devices, and then determine if a reliable
link can be established.
Short-Range Network
A short-range network will have the SEL-FT50 devices deployed within a short
distance of the SEL-FR12. A deployment is considered to be a short-range net-
work when the installed SEL-FT50 devices are visible from the SEL-FR12
antenna and there are no obstructions between the two devices.
Short-range networks do not require extensive system planning, but a simple link
budget estimation should still be performed to determine if the link margin is
acceptable (see Appendix C: Link Budget Analysis on page 48 for details). Select
an SEL-FR12 antenna and feeder cable from the list shown in Table 2 and
Table 3 and include the gain and loss information for these components in the
link budget analysis.
When the distance between the SEL-FR12 and the SEL-FT50 devices is short,
you can leave the device in low-gain mode. See Setting SEL-FR12 Receiver Gain
on page 25 for instructions on when to use low gain vs. high gain. Low-gain
mode will limit the range of the SEL-FR12 but will reduce RF interference from
other devices.
SEL-RP50 Fault Repeaters can also be used on short range networks without
extensive planning, provided they are properly configured and installed as
described in Appanedix D.
Perform an Area Study
Most SEL-FT50/SEL-FR12 links require that you are able to see the SEL-FT50
from the SEL-FR12 antenna. If you cannot see the SEL-FT50 from the
SEL-FR12 antenna, perform an area study to determine if the link will work
properly. Perform an area study starting at the proposed SEL-FR12 site to deter-
mine if the site provides effective coverage. The area study determines the
expected receive power levels in the area around the SEL-FR12 site. The area
study combines the RF characteristics of the system (e.g., system TX power,
cabling losses, antenna gain, etc.), local geography, and ground cover to deter-
mine expected received power levels in the area around the SEL-FR12 sites.
Effective links require 15 dB of fade margin (how much the received power level
exceeds the received sensitivity). If the area study says that the link has less than
15 dB of margin, you should try raising the receiver antenna higher above
ground, using a receiver antenna with higher gain, or using a different receiver
site entirely.
In situations where obstacles such as trees, terrain, or buildings are blocking line-
of-sight from one or more SEL-FT50s, consider installing one or more
SEL-RP50 Fault Repeaters per SEL-FT50 on the same feeder as the obscured
SEL-FT50s. The repeaters will generally be installed in sets of three. For longer
obstruction zones, multiple repeater sites can be used (up to five). The suitability
of each segment (between the SEL-FT50 site and the SEL-RP50 site, between
successive SEL-RP50 sites, or between the SEL-RP50 site and the SEL-FR12)
can be determined by using the simple the Short-Range Network method, above.
Refer to Appendix D: SEL-RP50 Fault Repeater Detailed Implementation on
page 54 when considering the use of SEL-FT50s.
NOTE: Only one repeater may be
used with SEL-FT50s manufactured
prior to May 2021.
NOTE: SEL-RP50s are not available
in all markets. See
Tab le 13 .

18
SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Network Deployment Overview
An area study may also be performed for system with proposed repeaters. In this
case, the characteristics of each segment must be considered. Use the SEL-RP50
receive sensitivity and EIRP values listed in Specifications.
If you do not have a clear line of sight between the SEL-FT50 and the
SEL-FR12, you may wish to set up a repeater at a high point between the trans-
mitter and the receiver, where the SEL-FR12 is at the repeater site along with an
SEL-3031, which can be used as a backhaul device. The SEL-3031 repeater solu-
tion adds additional latency to the link.
The area study is only a software-based estimate and should always be accompa-
nied by on-site analysis and testing.
Planning
SEL-FT50 Site Survey
Survey the SEL-FT50 installation site to check for local obstructions between the
SEL-FT50 and SEL-FR12. If an obstruction does exist, consider whether the
SEL-FT50 location could be moved to a nearby span to avoid the obstruction
without compromising the application of the device, as shown in Figure 14.
In systems where the line-of-sight cannot be maintained, SEL-RP50 Fault
Repeaters can be installed along the distribution feeder to help carry the wireless
signals around obstacles. For best results these must be installed on the same
feeder as the SEL-RP50s being repeated, one per phase, as shown in Figure 15.
See Appendix D: SEL-RP50 Fault Repeater Detailed Implementation on page 54
for further examples and implementation details.
Figure 14 Alternative SEL-FT50 Location
Figure 15 Use SEL-RP50s to Avoid an Obstruction -- need updated drawing
NOTE: SEL-RP50 Fault Repeaters
are not available in all countries. See
Tab le 13 .
Relocation
Primary
SEL-FT50
Location
Alternative
SEL-FT50
Location
>15 dB Link Margin
<15 dB Link Margin
SEL-FR12
Location
Obstruction

19
Date Code 20210405 Instruction Manual SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Network Deployment Overview
If an alternative SEL-FT50 site is not available, consider whether the SEL-FR12
location could be moved to another point with better line of sight. Use the
SEL-3031 as a backhaul device to carry the data back to the relay or recloser con-
trol that needs the fault information, as shown in Figure 16.
Path Study
A path study, rather than an area study, can be performed for networks with only
a few SEL-FT50 devices that have either a long link range or have obstructions in
the link path. A path study can also complement an area study for specific links
in a larger network where received signal level is not optimal. Performing a path
study helps you understand the propagation characteristics of the link and
whether reliable communication is achievable. SEL provides radio path studies
for as many as five SEL-FT50 links at no cost. For larger studies, SEL offers this
service, as well as link planning and testing, for a fee through SEL Engineering
Services, Inc. (contact SEL for details). Only one path study is needed for each
group of collocated SEL-FT50 devices.
On-Site Testing
SEL-FR12 Installation
Install the network SEL-FR12 at the identified site or set of sites and enable the
radio before installing any SEL-FT50 devices. Follow the procedures in Physical
Installation on page 35 for instructions on the physical installation. Commission
the SEL-FR12 as described in Commissioning the SEL-FR12 on page 23.
Verify the radio is enabled and functioning with a nearby SEL-FT50 device. For
this test, use the SEL-FT50 with a mini current loop to test the link. Simulate a
fault by using the mini current loop and verify that the device registers a fault on
the SEL-FR12 front-panel LEDs. The RSSI information available will indicate
the signal strength, verifying RF connectivity and initial SEL-FR12 setup. See
Receive Signal Strength Indicator on page 26 for details. Now you are ready to
install SEL-FT50 devices on the distribution system.
Figure 16 Using the SEL-3031 as a Repeater for Links Without a Clear Line of
Sight
Obstruction
SEL-FT50
Location
>15 dB Link Margin
<15 dB Link Margin
Relay or Recloser
Control Used in
SEL-FT50/SEL-FR12
Application
SEL-FR12 and SEL-3031
Repeater Site
NOTE: After installing the SEL-FT50
on the Mini Current Loop, press the
button on the loop to simulate a fault.
You should see a FAULT LED on the
SEL-FR12 right away. The LINK LED will
illuminate within 80 s if more than
one fault is triggered.

20
SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Device Installation
SEL-FT50 Site Installation
At the installation site, activate the SEL-FT50 by using a mini current loop. The
mini current loop uses 120 Vac power so bring an inverter and extension cords to
the SEL-FT50 installation site. Verify the RF connectivity by using a local
SEL-FR12 (a different SEL-FR12, not installed in a cabinet) with an indoor
antenna (SEL part number 235-0108). Verify that the local SEL-FR12 registers
the local SEL-FT50 by examining the front-panel LEDs.
Set the SEL-FT50 devices according to Settings and Configuration on page 30.
Install the SEL-FT50 devices by following the instructions in Physical Installa-
tion on page 35.
Verify that the installed SEL-FT50 devices can communicate with the
SEL-FR12. Check that the LEDs are reporting the correct LINK status (solid green
LED), and that the RSSI information is similar to the expected signal level deter-
mined in the area study.
When SEL-RP50s are part of the system, and the line current during commis-
sioning is less than 40 A, the appearance of LINK status at the SEL-FR12 may be
delayed by 30 minutes. When more than one SEL-RP50 site is installed this
delay grows by up to 30 minutes per additional site.
The SEL-FT50 only transmits Link messages when it is able to harvest line cur-
rent greater than 5 A. If the line current is known to be higher than 5 A and the
LINK LED does not assert after waiting the expected time, the SEL-RP50 Unit ID,
Network ID, or Repeater ID setting might be incorrectly configured.
Path or area study modeling of ground cover may not account for specific objects
that could impact individual link reliability. A tree or building close to an
SEL-FT50 installation could prevent reliable communication. If there is unreli-
able communication, determine if it is possible to change the SEL-FT50 location
to avoid the obstruction without compromising the application of the device.
These steps should be repeated for all collocated SEL-FT50 installations.
Device Installation
SEL-FR12
The SEL-FR12 uses two 10-position control (DIP) switches to set the wireless
network identification (Network ID) of the associated SEL-FT50 Fault Transmit-
ters, the baud rate and addresses for the MIRRORED BITS serial communications
port, and the separate receiver gain values for the SEL-FT50 Fault Transmitters.
The control (DIP) switch assignments are listed on the SEL-FR12 enclosure. The
switch positions are labeled 1 through 20, but only 1 through 14 are used.
Physical Installation
Install the SEL-FR12 first for easier commissioning when you install the
SEL-FT50 Fault Transmitters.
For simplest installation, place the SEL-FR12 inside the recloser control cabinet,
powered by the 12 Vdc auxiliary power supply of the SEL-651R. However, it can
be installed with any device that communicates through MIRRORED BITS commu-
nications. The SEL-FR12 must be connected to an antenna that is outside the
recloser control cabinet and can connect to a coaxial cable run with proper