9.5
Date Code 20150130 Instruction Manual SEL-787 Relay
Analyzing Events
Event Reporting
Currents, Voltages, and RTD Temperatures
The relay determines the maximum winding current during an event. The
instant the maximum winding current occurs is marked by an asterisk (*) in
the event report (see Figure 9.3). 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 winding current was measured. The currents displayed
are listed below:
➤ Winding Currents (IAWn,IBWn, ICWn, IGWn {n =1and2})
➤ Neutral Current (IN)
The
Voltage Mag fields display the primary voltage magnitudes at the instant
when the maximum winding current was measured. The voltages displayed
are listed below:
➤ DELTA_Y := WYE
➢ Phase-to-Neutral Voltages (VAN, VBN, VCN)
➢ Residual Voltage VG, calculated from VAN, VBN, VCN
➤ 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 listed below:
➤ 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 9.2 for a sample event history. Use this report to view
the events that are presently stored in the SEL-787.
The event history contains the following:
➤ Standard report header
➢ Relay and terminal identification
➢ Date and time of report
➢ Time source (Internal or IRIG-B)
➤ Event number, date, time, event type (see Table 9.1)
➤ Maximum current
➤ Frequency (actual frequency if voltage card is available
otherwise the nominal frequency)
➤ Target LED status
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