Schweitzer Engineering Laboratories SEL-311C - Synchronism Check Applications for Automatic Reclosing and Manual Closing

3.54
SEL-311C Relay Instruction Manual Date Code 20060320
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Synchronism Check Elements
with V
P
(Angle Difference = 0 degrees). Instead, it just
checks to see that the Angle Difference is less than
angle settings 25ANG1 or 25ANG2.
If the Angle Difference is less than angle setting
25ANG1 or 25ANG2, then the corresponding Relay
Word bit, 25A1 or 25A2, asserts to logical 1 for
1/4 cycle.
For example, if SEL
OGIC control equation setting
79CLS (Reclose Supervision) is set as follows:
79CLS = 25A1 + ...
and the angle difference is less than angle setting
25ANG1 at that “instant,” setting 79CLS asserts to
logical 1 for 1/4 cycle, allowing the sealed-in open
interval time-out to propagate on to the close logic in
Figure 6.1. Element 25A2 operates similarly.
Synchronism Check
Applications for
Automatic Reclosing
and Manual Closing
Refer to Close Logic on page 6.2 and Reclose Supervision Logic on page 6.5.
For example, set 25ANG1 = 15 degrees and use the resultant synchronism
check element in the reclosing relay logic to supervise automatic reclosing,
e.g.,
79CLS = 25A1 + ... (see Figure 6.2)
Set 25ANG2 = 25° and use the resultant synchronism check element in
manual close logic to supervise manual closing (for example, assert IN106 to
initiate manual close), e.g.,
CL = IN106 * (25A2 + ... ) (see Figure 6.1)
In this example, the angular difference across the circuit breaker can be
greater for a manual close (25 degrees) than for an automatic reclose
(15 degrees).
A single output contact (e.g., OUT102 = CLOSE) can provide the close
function for both automatic reclosing and manual closing (see Figure 6.1 logic
output).