
3.17
Date Code 20080213
Instruction Manual
SEL-351A Relay
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Time-Overcurrent Elements
q
From Figure 4.24. Directional Control logic input is constantly asserted to
logical 1 in SEL-351A-1.
Figure 3.14
Phase Time-Overcurrent Element 51PT (With Directional Control
Option in SEL-351A)
Accuracy
Pickup:
±0.05 A secondary and ±3% of setting
(5 A nominal phase current inputs,
IA
,
IB
,
IC
)
±0.01 A secondary and ±3% of setting
(1 A nominal phase current inputs,
IA
,
IB
,
IC
)
Curve Timing:
±1.50 cycles and ±4% of curve time for currents between (and including)
2 and 30 multiples of pickup
Logic Outputs (51PT Element Example)
The resultant logic outputs in
are the Relay Word bits listed in
.
51PP
(Max. Phase)
I
P
Setting
51PTC
Torque Control Switch
Directional Control
(asserted to logical 1
continuously if E32 = N)
q
(Level 1)
SEL
OGIC
Torque Control
51PT Phase
Time-Overcurrent Element
Curve Timing and Reset Timing
Settings
51PP
Pickup
51PC
Curve
Type
51PTD
Time
Dial
51PRS
Electromechanical
Reset? (Y/N)
Pickup
Curve
Timeout
Reset
51P
51PR
51PT
Torque
Control
TCP State
Switch Position
Logical 1
Closed
Logical 0
Open
Logic Point TCP Controls the Torque Control Switch
Setting
51PRS =
Reset Timing
Y
Electromechanical
N
1
Cycle
TCP
Relay
Word
Bits
SEL
OGIC
Setting
Table 3.3
Phase Time-Overcurrent Element (Maximum Phase) Logic
Outputs
Relay
Word
Bit
Definition/Indication
Application
51P
Maximum phase current, I
P
, is greater
than phase time-overcurrent element
pickup setting 51PP.
Element pickup testing or other con-
trol applications. See
.
51PT
Phase time-overcurrent element is
timed out on its curve.
Tripping and other control applica-
tions. See
51PR
Phase time-overcurrent element is
fully reset.
Element reset testing or other control
applications.
Содержание SEL-351A
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