Sel 751A - Currents, Voltages, and RTD Temperatures; Event History

9.5
Date Code 20100129 Instruction Manual SEL-751A Relay
Analyzing Events
Event Reporting
The event type designations AG through CAG in Table 9.1 are only entered in
the
Event field if the fault type is determined successfully.
Currents, Voltages, and RTD Temperatures
The Current Mag fields display the primary current magnitudes at the instant
the TRIP Relay Word bit asserted or the ER equation asserted. The currents
displayed are listed below:
➤ 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
the TRIP Relay Word bit asserts or the ER equation asserts. The voltages
displayed are listed below:
➤ DELTA_ Y := WY E
➢ 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 listed below:
➤ 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 9.2 for a sample event history. Use this report to view
the events that are presently stored in the SEL-751A.
The event history contains the following:
➤ Standard report header
➢ Relay and terminal identification
➢ Date and time of report
➢ Time source (if IRIG-B model)
➤ Event number, date, time, event type (see Table 9.1)
ER Trigger
ER Equation assertion. Phase involvement is indetermi-
nate.
Trip
TRIP with no known cause
a
ABG, BCG, and CAG detection requires at least one of the 50G or 51G elements to be enabled
and picked up (GFLT = 50G1 + 50G2+ 50G3 + 50G4 + 51G1 + 51G2 = 1). Overcurrent trip
includes all 50/51 P, Q, N, or G elements.
Table 9.1 Event Types (Sheet 2 of 2)
Event Type Event Type Logic