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

2
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

3
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.

4
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

5
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).

6
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.

7
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?
?
??

8
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

9
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)

10
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