S&C 6801 User Manual

Switch Control Setup
In a wye system, when a phase loses voltage, the voltage reading is 0 (zero) for that
phase, so a phase imbalance can be detected easily.
In a delta system, the loss of one phase results in sensor readings with magnitudes
slightly more than half of the normal phase-to-phase voltage. Simultaneous loss of two
phases is not detectable as a Phase Imbalance condition.
When the Phase Loss Protection feature trips the switch open and the phase imbal-
ance has corrected for the Auto-Reclose Time Threshold condition, the switch will
reclose.
Phase Loss Protection Voltage Loss Threshold (RMS Volts)
When voltage on one or two phases drops below this value, the switch control starts
the Phase Loss Protection Time Threshold timer. If the voltage stays continuously
below this voltage until the timer expires, the control opens the line switch. When this
setpoint is set to the N/A option, the switch control uses the Loss of Voltage Threshold
setpoint (on the Setup>General>Site-Related screen) for both three-phase voltage loss
and for phase-loss protection. A higher value for this setpoint lets the switch control
detect phase-loss conditions where there are delta-connected transformers and they
still provide accurate sensing of true three-phase outages. A threshold of approximately
75% of the normal phase voltage (90 volts on a 120-volt base) is recommended. (Range:
1-150; Step: 1; Default: N/A)
When this setpoint is set to other than the N/A option, it is also used as the Return
of Voltage threshold setpoint.
Phase Loss Protection Time Threshold (seconds)
This is the number of seconds the switch control waits after it detects a loss of phase
voltage before it trips open the switch. When the timer expires if the voltage on one or
two phases has remained below the Phase Loss Protection Voltage Loss Threshold
setting, and the current has remained continuously below the Phase Loss Protection
Current Threshold setting, the control trips open the line switch. (Range: 1-255; Step:
1; Default: 30)
At a minimum, this time should exceed the reaction time of any single-phase source-
side protective device.
Phase Loss Protection Current Threshold (amps)
When minimizing loss-of-phase conditions, the control must switch the remaining live
phases. To make sure these live phases have current ows that are safe for the switch,
set this setpoint to the load-break rating of the line switch. (Range: 100-25,500; Step:
100; Default: 600)
Automatic Reclose Section
Phase Loss Protection with Auto Reclose
When the Automatic Reclose feature is enabled, this is the number of seconds the
switch control waits (after three-phase voltage is sensed) before it recloses the switch.
Note: This feature is not applicable to the IntelliTeam system and should be disabled
when the IntelliTeam system is enabled.
Automatic Reclose Time Threshold (sec)
When Automatic Reclose mode is enabled, this is the number of seconds the switch control
waits (after three-phase voltage is sensed) before it recloses the switch. (Range: 1-255; Step:
1; Default: 30)
Note: This must be set to the No setting when using the IntelliTeam system.
S&C Instruction Sheet 1045-530 43

S&C 6801 Specifications

General

Brand	S&C
Model	6801
Category	Controller
Language	English