Schweitzer Engineering Laboratories SEL-352-1, Instruction Manual

Page: 133 / 444

Date Code 20010731 Close Logic 4-9
SEL-352-1, -2 Instruction Manual
Dead Line/Bus Under Voltage (27D)
Range: 1.0–120.0 V in 0.1-V steps
Set 27D for the X-and Y-side voltage to indicate dead (de-energized) equipment. The
recommended setting is 10 V for a nominal 67 V application. Applications, where mutual
coupling or capacitive coupling from parallel lines or other phases exists, will require a higher
setting. In these cases, set the 27D setting to 120 percent of the voltage caused by coupling.
Verify that a single contingency for the thermal logic does not drop the voltage below the 27D
setting. When voltage drops below the 27D setting, the thermal logic is disabled. See
Thermal
Logic in Section 3: Breaker Logic.
Controlled Closing Scheme Selection (CLSLOG)
Range: OFF, 1, 2, CUSTOM
Use either of two provided controlled closing schemes and modify either of these to meet your
specific application. Enable a staggered close scheme for single-pole closing by setting
CLSLOG = 1. Each pole is delayed by a timer so that transients may be reduced during the close
operation. Enable a complete point-on-wave closing, synchronism checking, live-line dead-bus
closing, and dead-line live bus closing by setting CLSLOG = 2.
Set CLSLOG = CUSTOM to modify the close logic. When set to CUSTOM, all settings are
shown including the SEL
OGIC
control equations. Use these settings for a modified close logic or
for an entirely different application.
Close Dropout (CLSdo)
Range: 0–16383 cycles in 1/4-cycle steps
Set the close dropout time CLSdo to a value that makes certain the breaker close coil has been
energized, and that the breaker has had time to close. When standard output contacts on the
SEL-352 Relay energize the close coil, you must use an auxiliary breaker contact to interrupt the
close coil current. The CLSdo timer holds the SEL-352 Relay output contact closed for the
specified time. A recommended setting is the same as the SlowCl setting. Based on the default
setting of SlowCl = 83, set CLSdo = 5 cycles.
If the high current interrupting contacts are used, the only concern for setting CLSdo is that the
close coil must be energized long enough to close the breaker. The auxiliary contact may also be
removed from the circuit if the close coil current is within the specified capabilities of the output
contacts. Refer to
Section 2: Installation . When the high current interrupting contacts are not
available, apply an SEL-9501 across a standard output contact to give the contact greater
interrupt capability. Contact the factory for more information about the SEL-9501 Contact Arc
Suppressor.