Schweitzer Engineering Laboratories SEL-351A - Figure 3.27 Synchronism Check Voltage Window and Slip Frequency Elements

3.38
SEL-351A Relay Instruction Manual Date Code 20080213
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Synchronism Check Elements (Not in SEL-351A-1)
Accuracy
Voltage Pickup:
±2 V and ±2% of setting
Voltage Transient Overreach:
±5% of setting
Slip Pickup:
0.003 Hz
Angle Pickup:
±4°
q See bottom of Figure 3.28; w to Figure 3.28.
Figure 3.27 Synchronism Check Voltage Window and Slip Frequency Elements
59VP
59VS
59VA
SSLOW
SFAST
SF
w
Relay
Word
Bits
25VLO
Setting
25SF
Setting
BSYNCH
SELOGIC
Setting
25VHI
V
P
V
S
Setting
Wye-Connected:
Select V
A
, V
B
, or V
C
with setting SYNCP;
if SYNCP = 0–330˚, then V
P
= V
A
Delta-Connected:
Select V
AB
, V
BC
, or V
CA
with setting SYNCP;
if SYNCP = 0–330˚, then V
P
= V
AB
Block Synchronism Check
V
A
(wye-connected)
V
AB
(delta-connected)
V
P
Within
"Healthy Voltage" Window
V
S
Within
"Healthy Voltage" Window
V
A
or V
AB
Within
"Healthy Voltage" Window
Slip
Frequency
Calculator
Enable
Frequency of V
P
less than or equal to
Frequency of V
P
greater than
Frequency of V
S
(f
p
≤ f
S
)
Frequency of V
S
(f
p
> f
S
)
3 CYC
0
to Angle Difference
Calculator q
Slip Frequency
Maximum Slip Frequency
Absolute Value
Slip
Frequency Element
High Threshold
Low Threshold
High Threshold
Low Threshold
High Threshold
Low Threshold
Courtesy of NationalSwitchgear.com