33
Date Code 20210405
Instruction Manual
SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System
Device Installation
This selection method guarantees that the SEL-FT50 picks up for any fault that
the protective device element can see. This setting method will perform well in
locations where fault current is much higher than load current.
The protection planner must consider the load current range on the distribution
system at each node, combined with the SEL-FT50 accuracy rating at currents
below the fault pickup. High load current levels may result in false assertion of
the SEL-FT50 fault detector. In most cases, this is acceptable because the super-
vising overcurrent element will not assert. However, the more frequent a load
condition is mistaken for a fault, and the longer each instance persists, the higher
the chance of the SEL-FT50 missing an actual fault. To avoid this situation, con-
sider selecting the SEL-FT50 Fault Pickup setting to be one step higher.
SEL-RP50 Settings and Configuration
The SEL-RP50 uses two internal eight-position switch banks to configure the
Unit ID, Network ID, and the Repeater ID.
The SEL-RP50 only reads settings during startup; changing settings while the
unit is turned on has no effect. Changing settings requires removal of device
power. The SEL-RP50 retains some energy in storage and may take a couple of
minutes to fully turn off. For an SEL-RP50 as part of the LINK to an SEL-FR12,
the device is fully turned off when the
LINK
LED for that unit starts blinking.
During bench testing, however, other device Link messages may keep the
SEL-FR12
LINK
LED illuminated. Waiting 5 minutes with the SEL-RP50
removed from its test current source will be long enough in these cases.
To begin, open the SEL-FT50 by twisting the bottom counter-clockwise. On the
inside of the device, you will see the two banks of switches. The switch positions
are labeled 1 through 8 on each of the two switch banks. The switch selections
are outlined on a label on the interior of the device, as shown in
Figure 22
.
Table 12
Fault Pickup Accuracy Considerations for FT50-0004/FT50-0007
(Europe and Mexico)
Fault Pickup Level
(rms)
Host Relay Pickup Setting
(rms)
Load Behind FT50
(rms)
50 A
> 75 A
< 25 A
100 A
> 130 A
< 70 A
200 A
> 260 A
< 140 A
400 A
> 480 A
< 320 A
600 A
> 720 A
< 480 A
800 A
> 960 A
< 640 A
1000 A
> 1200 A
< 800 A
1200 A
> 1440 A
< 960 A
