Date Code 20001006 Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements 3-51
SEL-351 Instruction Manual
Synchronism Check Applications for Automatic Reclosing and Manual Closing
Refer to Close Logic and Reclose Supervision Logic in Section 6: Close and Reclose Logic.
For example, set 25ANG1 = 15° 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 IN6 to initiate manual close):
e.g., CL = IN6 * (25A2 + ... ) (see Figure 6.1)
In this example, the angular difference across the circuit breaker can be greater for a manual close
(25§) than for an automatic reclose (15§).
A single output contact (e.g., OUT2 = CLOSE) can provide the close function for both automatic
reclosing and manual closing (see Figure 6.1 logic output).
FREQUENCY ELEMENTS
Six frequency elements are available. The desired number of frequency elements are enabled with
the E81 enable setting:
E81 = N (none), 1 through 6
as shown in Figure 3.30. Frequency is determined from the voltage connected to voltage terminals
VA-N (or VA-VB for delta).
Frequency Element Settings
Figure 3.29: Undervoltage Block for Frequency Elements
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
