Schweitzer Engineering Laboratories SEL-351A - Page 107

3.35
Date Code 20080213 Instruction Manual SEL-351A Relay
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Voltage Elements
Overvoltage Element Operation Example
Refer to Figure 3.22 (bottom of the figure).
Pickup setting 59P1P is compared to the magnitudes of the individual phase
voltages V
A
, V
B
, and V
C
. The logic outputs in Figure 3.22 are the following
Relay Word bits:
59A1 = 1 (logical 1), if V
A
> pickup setting 59P1P
= 0 (logical 0), if V
A
≤ pickup setting 59P1P
59B1 = 1 (logical 1), if V
B
> pickup setting 59P1P
= 0 (logical 0), if V
B
≤ pickup setting 59P1P
59C1 = 1 (logical 1), if V
C
> pickup setting 59P1P
= 0 (logical 0), if V
C
≤ pickup setting 59P1P
3P59 = 1 (logical 1), if all three Relay Word bits 59A1, 59B1, and
59C1 are asserted (59A1 = 1, 59B1 = 1, and 59C1 = 1)
= 0 (logical 0), if at least one of the Relay Word bits 59A1,
59B1, or 59C1 is deasserted (e.g., 59A1 = 0)
Courtesy of NationalSwitchgear.com