3.19
Date Code 20080213 Instruction Manual SEL-351A Relay
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Time-Overcurrent Elements
If logic point TCP = logical 0, the Torque Control Switch is open and
maximum phase current, I
P
, cannot get through to the pickup comparator and
the curve timing/reset timing functions. The maximum phase current, I
P
,
effectively appears as a magnitude of zero (0) to the pickup comparator and
the curve timing/reset timing function.
Directional Control Option (Not in SEL-351A-1)
Refer to Figure 3.14.
See Figure 4.24 for more information on the optional directional control. If
the directional control enable setting E32 is set:
E32 = N
then directional control is defeated, and the directional control input into logic
point TCP in Figure 3.14 is asserted to logical 1 continuously. Then, only the
corresponding SEL
OGIC control equation torque control setting 51PTC has to
be considered in the control of logic point TCP (and, thus, in the control of the
Torque Control Switch and phase time-overcurrent element 51PT).
Torque Control
Refer to Figure 3.14.
SEL
OGIC control equation torque control settings (e.g., 51PTC) cannot be set
directly to logical 0. The following are setting examples of SEL
OGIC control
equation torque control setting 51PTC for phase time-overcurrent element
51PT.
Example 1: 51PTC = 1.
NOTE: All overcurrent element
SEL
OGIC control equation torque
control settings are set directly to
logical 1 (e.g., 51PTC = 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 51PTC set directly to logical 1:
Then only the corresponding directional control input from Figure 4.24
has to be considered in the control of logic point TCP (and, thus, in the
control of the Torque Control Switch and phase time-overcurrent element
51PT).
If directional control enable setting E32 = N, then logic point TCP =
logical 1 and, thus, the Torque Control Switch closes and phase time-
overcurrent element 51PT is enabled and nondirectional.
Example 2: 51PTC = IN105.
Input IN105 deasserted (51PTC = IN105 = logical 0):
Then logic point TCP = logical 0 and, thus, the Torque Control Switch
opens and phase time-overcurrent element 51PT is defeated and
nonoperational, regardless of any other setting.
Input IN105 asserted (51PTC = IN105 = logical 1):
Then only the corresponding directional control input from Figure 4.24
has to be considered in the control of logic point TCP (and, thus, in the
control of the Torque Control Switch and phase time-overcurrent element
51PT).
If directional control enable setting E32 = N, then logic point TCP =
logical 1 and, thus, the Torque Control Switch closes and phase time-
overcurrent element 51PT is enabled and nondirectional.
Courtesy of NationalSwitchgear.com
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