3.35
Date Code 20060320 Instruction Manual SEL-311C Relay
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Time-Overcurrent Elements
Torque Control Switch Open
If the Torque Control Switch in Figure 3.24 is open, maximum phase current,
I
ABC
, cannot get through to the pickup comparator (setting 51PP) and the
curve timing/reset timing functions. For example, suppose that the Torque
Control Switch is closed, I
ABC
is:
I
ABC
> pickup setting 51PP
and the phase time-overcurrent element is timing or is timed out on its curve.
If the Torque Control Switch is then opened, I
ABC
effectively appears as a
magnitude of zero (0) to the pickup comparator:
I
ABC
= 0 A (effective) < pickup setting 51PP
resulting in Relay Word bit 51P deasserting to logical 0. I
ABC
also effectively
appears as a magnitude of zero (0) to the curve timing/reset timing functions,
resulting in Relay Word bit 51PT also deasserting to logical 0. The phase
time-overcurrent element then starts to time to reset. Relay Word bit 51PR
asserts to logical 1 when the phase time-overcurrent element is fully reset.
Torque Control
Refer to Figure 3.24.
SEL
OGIC control equation torque control settings (e.g., 51PTC) cannot be set
directly to logical 0. The following are settings examples of SEL
OGIC control
equation torque control setting 51PTC for phase time-overcurrent element
51PT.
51PTC = 1 Setting 51PTC set directly to logical 1:
The Torque Control Switch closes and phase time-overcurrent element
51PT is enabled and nondirectional.
51PTC = IN105
Input IN105 deasserted (51PTC = IN105 = logical 0):
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):
51P = 1 (logical 1), if I
ABC
> pickup setting 51PP and the phase
time-overcurrent element is timing or is timed out on its
curve
= 0 (logical 0), if I
ABC
≤ pickup setting 51PP
51PT = 1 (logical 1), if I
ABC
> pickup setting 51PP and the phase
time-overcurrent element is timed out on its curve
= 0 (logical 0), if I
ABC
> pickup setting 51PP and the phase
time-overcurrent element is timing, but not yet timed out
on its curve
= 0 (logical 0), if I
ABC
≤ pickup setting 51PP
51PR = 1 (logical 1), if I
ABC
≤ pickup setting 51PP and the phase
time-overcurrent element is fully reset
= 0 (logical 0), if I
ABC
≤ pickup setting 51PP and the phase
time-overcurrent element is timing to reset (not yet fully
reset)
= 0 (logical 0), if I
ABC
> pickup setting 51PP and the phase
time-overcurrent element is timing or is timed out on its
curve
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.
To Next Page
