Schweitzer Engineering Laboratories SEL-311C - Page 115

3.47
Date Code 20060320 Instruction Manual SEL-311C Relay
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Synchronism Check Elements
q From Figure 3.30; w Figure 6.1.
Figure 3.31 Synchronism Check Elements
[select from V
A
, V
B
, V
C
or V
AB
, V
BC
, V
CA
with setting SYNCP]
with setting SYNCP]
Angle Difference
Increasing
—
+
—
+
Angle
Difference
Angle
Difference
0.005 Hz < slip frequency ≤ setting 25SF
Operation of Synchronism Check Elements if voltages V
P
and V
S
are slipping:
[TCLOSD = OFF and 25SF = 0.500] OR [slip frequency < 0.005 Hz ]
Operation of Synchronism Check Elements if voltages V
P
and V
S
are
static
(not slipping):
25A1
25A2
Synchronism
Check
Element 2
Synchronism
Check
Element 1
—
+
—
+
Enable
Angle
Difference
Calculator
Slip Frequency Element
Max. Angle 2
Max. Angle 1
SF
V
P
V
S
25ANG2
25ANG1
or V
AB
, V
BC
, V
CA
[select from V
A
, V
B
, V
C
(absolute
value)
Synchronize at
Angle Difference = 0˚
(absolute
value —
compensated
by setting
TCLOSD)
Last check of
SEL
OGIC setting 79CLS
(see w)
Max. Angle 2
25ANG2
Slip Frequency Element
Slip
Frequency
(q)
V
P
Synchronism
Check
Element 1
Synchronism
Check
Element 2
25A2
Max. Angle 1
Breaker
Close Time
TCLOSD
25ANG1
V
S
0˚
25A1
SF
Enable
Angle
Difference
Calculator
+
—
Relay
Word
Bit
Settings
Relay
Word
Bits
Relay
Word
Bits
Relay
Word
Bit
Settings