10.7
Date Code 20170927 Instruction Manual SEL-751 Relay
Analyzing Events
Event Reporting
Fault Locator Operating Window
The SEL-751 uses a 15-cycle subset of the event report data to calculate the
event type and fault location. For Global settings LER := 64 or LER :=180, the
relay processes the portion of stored data that includes the event report trigger.
For LER := 15, the entire event report is available for calculation of the event
type and fault location.
It is possible for the event type or fault location to be calculated from a
different portion of the event report than expected. For example (with default
settings), when the event report is first triggered by overcurrent element
pickup (ER), but the trip occurs more than 12 cycles later, the conditions at the
time of trip are not considered (unless covered by a new event report).
Currents, Voltages, and RTD Temperatures
The relay determines the maximum phase current during an event. The instant
the maximum phase current occurs is marked by an asterisk (*) in the event
report (see Figure 10.3). This row of data corresponds to the analogs shown in
the summary report for the event.
The
Current Mag fields display the primary current magnitudes at the instant
when the maximum current was measured. The currents displayed are as
follows:
➤ Line Currents (IA, IB, IC)
➤ Neutral Current (IN)
➤ Residual Current (IG), calculated from IA, IB, IC
The
Voltage Mag fields display the primary voltage magnitudes at the instant
when the maximum current was measured. The voltages displayed are as
follows:
➤ DELTA_Y := WYE
➢ Phase-to-Neutral Voltages (VAN, VBN, VCN)
➢ Residual Voltage VG, calculated from VA, VB, VC
➤ DELTA_Y := DELTA
➢ Phase-to-Phase Voltages (VAB, VBC, VCA)
If the RTDs are connected, the hottest RTD (°C) fields display the hottest RTD
reading in each RTD group. The hottest RTD temperatures in degrees
centigrade (°C) are as follows:
➤ Winding
➤ Bearing
➤ Ambient
➤ Other
Event History
The event history report gives you a quick look at recent relay activity. The
relay labels each new event in reverse chronological order with
1 as the most
recent event. See Figure 10.2 for a sample event history. Use this report to
view the events that are presently stored in the SEL-751.
The event history contains the following:
➤ Standard report header
➢ Relay and terminal identification
➢ Date and time of report
➢ Time source
To Next Page
Loading...
