GE Entellisys 4.0 Application Manual page 22

Section 7. Protection
voltages used for each synch check function are
fixed when they are selected.
For each synch check function the following settings
must be made:
• Bus-1 voltage source
• Bus-2 voltage source
• Maximum voltage differential allowed between
voltage sources; may be set at 0–90v in increments
of 0.5v.
• Maximum frequency differential allowed between
buses; may be set at 0–2 Hz in increments of 0.1 Hz.
• Maximum phase-angle differential allowed
between buses; may be set at 0–60 degrees in
increments of 1 degree.
• Bus 1 live-bus threshold is the voltage above which
the bus is considered to be live, programmable
at 50–100% of the nominal PT rating, in 1%
increments. The line-neutral voltage is used with
wye systems and phase-phase with delta systems.
• Bus 2 live-bus threshold functions like bus 1 with
a separate adjustment.
• Bus 1 dead-bus threshold is the voltage below
which the bus is considered to be dead, program-
mable at 5–50% of the nominal PT rating, in 1%
increments. The line-neutral voltage is used with
wye systems and phase-phase with delta systems.
• Bus 2 dead-bus threshold functions like bus 1
with a separate adjustment.
• Configurations under which the "Dead Source"
status is set to true:
— None – dead source function is disabled
— LV1 and DV2 – Voltage source 1 live and voltage
source 2 dead
— DV1 and LV2 – Voltage source 1 dead and
voltage source 2 live
— DV1 or DV2 – Voltage source 1 dead or voltage
source 2 dead
— DV1 or DV2 – One voltage source is dead, the
other is live
— DV1 and DV2 – Both sources are dead
Note that a source is considered dead when all
phase voltages are below the dead-bus threshold.
When all phase voltages are above the live-bus
threshold, a source is defined as energized.
Each synch check function verifies that the two
40
sources have equal programmed PT primary voltage
and configuration (delta or wye). If both parameters
are not the same for both sources, the CPU logs
an event and disables that synch check function.
The synch check function applies a 3% hysteresis
factor to the voltage, frequency, phase, live-bus,
and dead-bus thresholds.
Each synch check function provides the following
status information:
• Synchronous Live – true if all three phases at
both sources are above the live-bus threshold
and in synchronism (i.e., all three phases satisfy
the programmed voltage, frequency, and phase
differential criteria), false otherwise.
• Dead Source – true if the programmed dead-bus
configuration condition is true.
• Close – true if Synchronous Live is true or Dead
Source is true.
The relay function may be suspended with Flex Logic.
High Current Alarm and High Current Trigger Relay
There are two high current functions available in
Entellisys. The single point High Current Alarm is
assigned to a single breaker and has pickup
adjustments of 50-200% of the breaker long time
setting, with an adjustable delay of 1-15 seconds.
This function, factory-configured for a specific
breaker, can provide an alarm point on the Alarm
Screen and is available to FlexLogic for any control
scheme that may need to be invoked when the
breaker load current exceeds the preset alarm value.
The High Current Trigger Relay is packaged with
system-wide Waveform Capture and provides
expanded pickup settings with shorter delays for
use in detecting and analyzing short duration cur-
rents that might be encountered with motor starting
or other fast changing load currents. The pickup
current setting range is 0.1 to 9 times the breaker
long time pickup, which allows the High Current
Trigger Relay to be used for a wide range of load
currents. The time delay is 1-120 half cycles (0.0833 –
1 sec). The user can select whether waveforms
should be captured for each event and can also
set a maximum number of waveform captures.