GE PACSystems RX3i User Manual page 13

RX3i Power Sync and Measurement System
Subject
Breaker Delay
Breaker Delay = 0
Special Case
Delta Power Configurations
Nominal Voltage
Nominal Current
Scaling for PT and CT Ratios
ANSI Alarm Delays
Relay Output Options
Voltage Configuration
When the ANSI 25 Breaker Delay parameter is set to a non-zero value, the phase
angle difference at which CloseRelayOK (%I offset 7) is set and the IC694ACC200
relay outputs close varies, in direct proportion to the rate of change of the phase
angle of Grid 2 relative to Grid 1. Higher rates of phase angle change and larger
breaker delays require that the PSM assert CloseRelayOK earlier to ensure that the
breaker contacts close within the safe region set by the ANSI 25 Phase Shift
Threshold parameter (Phase_Shift_Thr).
If the PSM does not receive a request to Sync (%Q offset 16=0 and %Q offset 32=1)
in time for the relay outputs to close within the Phase Shift Threshold limits, it will not
assert CloseRelayOK until the next opportunity.
When the ANSI 25 Breaker Delay parameter is set to zero, the PSM reverts to classic
sync relay operation. The PhaseShiftOK bit will be set when
–Phase_Shift_Thr < Phase Shift < +Phase_Shift_Thr.
The PSM will not adjust its synchronization timing based on either the interval
between CloseRelayOK being set and the relay contacts actually closing or the rate of
change of the Phase Shift between the two grids. If a request to Sync (%Q offset
16=0 and %Q offset 32=1) is active at any time when the Phase Shift is within
±Phase_Shift_Thr, the CloseRelayOK bit and the relay outputs on the IC694ACC200
terminal assembly will be turned On.
Phase-to-Neutral voltages are not reported in Delta power configurations because
there is no Neutral reference.
Nominal Voltage refers to the:
Phase-to-Neutral RMS voltage in a WYE power system.
Phase-to-Phase RMS voltage in a Delta power system.
Setting a negative Nominal Current value implies that the IC694ACC200 grid inputs
are connected to a load (drawing power), rather than a power source (producing
power). The power and energy values will be reported as negative numbers. The CTs
must be wired with the correct polarity to achieve the negative power and energy
values. RMS current is necessarily reported as a positive number, due to the RMS
calculations.
The IC694PSM001 module reports the voltages and currents measured at the
IC694ACC200 terminals. Therefore, the application logic must correct for PT and CT
ratios to reflect the actual power grid voltages, currents, powers and energies.
Example:
Using 480V:120V PTs requires the application logic to multiply the reported voltage
values by 4. Using 100:5 CTs requires the application logic to multiply the reported
current values by 20. Since power and energy combine voltage and current, the
reported power and energy values must both be multiplied by 80 (4 x 20).
All ANSI alarm delays apply to both setting and clearing the alarms. A delay of 10
seconds means the grid must be in the alarm state for 10 continuous seconds before
the PSM will set the alarm bit; clearing the CloseRelayOK bit and opening the relay
outputs(if the grids were synchronized). Once the alarm is set, the alarm condition
must be eliminated for 10 continuous seconds for the alarm to be cleared.
The isolated, bipolar relay outputs are redundant. Both relay 1 and relay 2 follow the
CloseRelayOK %I offset 7 bit from the PSM. They can be connected in parallel to
increase the reliability of closing, or in series, to increase the reliability of opening, to
suit the needs of the application.
The Voltage Selection in the Proficy Machine Edition Hardware Configuration must
match both the physical cable connection to the IC694ACC200 terminal assembly
and the %Q offset 2 (Grid 1) and %Q offset 18 (Grid 2) configuration bits. Refer to
GFK-2749 for proper wiring and configuration information.
Description
13
GFK-2748C