Schweitzer Engineering Laboratories SEL-351A, Manual

Page: 77 / 666

3.5
Date Code 20080213
Instruction Manual SEL-351A Relay
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Instantaneous/Definite-Time Overcurrent Elements
Levels 1 through 4 in Figure 3.3 have corresponding directional control
options. See Figure 4.24 for more information on this optional directional
control. If the directional control enable setting E32 is set:
E32 =
N
then directional control is defeated, and the directional control inputs into all
four phase instantaneous/definite-time overcurrent element levels in
Figure 3.3 are asserted to logical 1 continuously. Then only the corresponding
SEL
OGIC®
control equation torque control settings have to be considered in
the control of the phase instantaneous/definite-time overcurrent elements.
For example, consider the Level 1 phase instantaneous/definite-time
overcurrent elements 67P1/67P1T in
Figure 3.3 . If the directional control
enable setting E32 is set:
E32 =
N
then the directional control input from Figure 4.24 (Level 1) is asserted to
logical 1 continuously. Then only the corresponding SEL
OGIC
control
equation torque control setting 67P1TC has to be considered in the control of
the phase instantaneous/definite-time overcurrent elements 67P1/67P1T.
SEL
OGIC
control equation torque control settings are discussed next.
Torque Control (Not in SEL-351A-1)
Levels 1 through 4 in Figure 3.3 have corresponding SEL
OGIC
control
equation torque control settings 67P1TC–67P4TC. SEL
OGIC
control equation
torque control settings cannot be set directly to logical 0. The following are
torque control setting examples for Level 1 phase instantaneous/definite-time
overcurrent elements 67P1/67P1T.
Example 1: 67P1TC = 1
NOTE:
All overcurrent element
SEL
OGIC
control equation torque
control settings are set directly to
logical 1 (e.g., 67P1TC = 1) for the
factory default settings . See SHO
Command (Show/View Settings) on
page 10.25 for a list of the factory
default settings.
Setting 67P1TC is set directly to logical 1:
Then only the corresponding directional control input from Figure 4.24
has to be considered in the control of phase instantaneous/definite-time
overcurrent elements 67P1/67P1T.
If directional control enable setting E32 = N, then phase instantaneous/
definite-time overcurrent elements 67P1/67P1T are enabled and
nondirectional.
Example 2: 67P1TC = IN105
Input IN105 deasserted (67P1TC = IN105 = logical 0):
Then phase instantaneous/definite-time overcurrent elements 67P1/
67P1T are defeated and nonoperational, regardless of any other setting.
Courtesy of NationalSwitchgear.com