SEL-351R Falcon Data Sheet
Schweitzer Engineering Laboratories, Inc.
4
The SEL-351R Falcon has two reset characteristic
choices for each time-overcurrent element. One choice
resets the elements if current drops below pickup for at
least one cycle. The other choice (for US or IEC curves
only) emulates electromechanical induction disc
elements, where the reset time depends on the time-dial
setting, the percentage of disc travel, and the amount of
current.
Sensitive Earth
Fault (SEF) Element
A sensitive earth fault (SEF) element with time delay (as
long as 16,000 cycles) can be set as sensitive as 5 A pri-
mary (assuming nominal recloser CT ratio of 1000:1).
Current channel
IN
with a 0.05 A secondary nominal rat-
ing provides this sensitivity (see Figure 15).
The front-panel SEF LED indicates any SEF element trip
(see Figure 14 and Table 4).
Custom Overcurrent Protection
Customize the overcurrent protection by reprogramming
the corresponding SEL
OGIC
control equations.
Metering and Monitoring
Complete Metering Capabilities
The SEL-351R Falcon provides extensive and accurate
metering capabilities. See Specifications on page 17 for
metering and power measurement accuracies.
Metered quantities include phase voltages and currents
(including demand currents); sequence voltages and
currents; power (including demand), frequency, and
energy; and maximum/minimum logging of selected
quantities (see Table 2). The recloser control reports all
metered quantities in primary quantities (current in
A primary and voltage in kV primary).
Recloser Wear Monitor
Reclosers suffer mechanical and electrical wear every
time they operate. The recloser wear monitor measures
unfiltered ac current at the time of trip and the number of
close-to-open operations as a means of monitoring this
wear. Every time the recloser trips, the recloser control
records the magnitude of the raw current in each phase.
This current information is integrated on a per-phase basis.
When the result of this integration exceeds the threshold
the recloser wear curve establishes, the SEL-351R
Falcon asserts a logic point for the affected phase. This
logic point can be routed for alarming or to modify
reclosing (e.g., shorten the number of reclosures). This
method of monitoring recloser wear is based solidly on
methods of breaker rating from breaker manufacturers.
Figure 4 shows three setpoints necessary to emulate a
breaker wear curve. Program the setpoints in Figure 4 to
customize the recloser wear curve.
The SEL-351R Falcon sets setpoints automatically
according to recommendations for reclosers in ANSI
C37.61-1973. Only the recloser type (oil or vacuum) and
the interrupt rating are necessary settings.
Table 2
Metering
a
a
If true three-phase voltage is not connected, the voltage (V
A,B,C
) uses phantom voltages derived from a single-phase voltage to calculate
MW/MVAR, MWh/MVARh, and power factor metering values.
Quantities
Description
Currents I
A,B,C,N
, I
G
Input currents, residual ground current (I
G
= 3I
0
, I
A
+ I
B
+ I
C
).
Voltages V
A,B,C
, V
S
Wye-connected voltage inputs, synchronism-check voltage input.
Power MW
A,B,C,3P
, MVAR
A,B,C,3P
Single- and three-phase megawatts and megavars.
Energy MWh
A,B,C,3P
, MVARh
A,B,C,3P
Single- and three-phase megawatt-hours and megavar-hours.
Power Factor PF
A,B,C,3P
Single- and three-phase power factor; leading or lagging.
Sequence I
1
, 3I
2
, 3I
0
Positive-, negative-, and zero-sequence currents.
Frequency, FREQ (Hz)
Instantaneous power system frequency (monitored on channel V
A
).