5.2
SEL-749M Relay Instruction Manual Date Code 20080918
Metering and Monitoring
Metering
Fundamental
Metering
All angles are displayed between –180 and +180 degrees. The angles are
referenced to VAB or VAN (for delta- or wye-connected PT, respectively) or
IA. If the voltage channels are not supported, or if VAB < 13 V (for delta-
connected PT) or VAN < 13 V (for wye-connected PT), the angles are
referenced to IA current.
Thermal Metering
The thermal metering function reports the present values of the RTD input
temperatures and several quantities related to the motor thermal protection
function (Table 5.2).
Table 5.1 Measured Values
Relay Option Meter Values
All Models Line Currents IA, IB, IC and IN (Core-Balance Ground Fault
Current) magnitudes (A) and phase angles (deg)
IG (Residual Ground Fault Current) magnitude (A) and phase
angle (deg)
IM (Average Current Magnitude)
Average Motor Load (x FLA)
Negative-Sequence Current (3I2)
Current Imbalance %
System Frequency (Hz)
With Voltage Option VAB, VBC, VCA or VAN, VBN, VCN, VG magnitudes (V)
and phase angles (deg)
Average Voltage (L-L or L-N)
Negative-Sequence (3V2)
Voltage Imbalance %
Real Power (kW)
Reactive Power (kVAR)
Apparent Power (kVA)
Power Factor
System Frequency (Hz)
Table 5.2 Thermal Meter Values
Relay Option Thermal Values
All Models Motor Load (xFLA)
Thermal Capacity Used %
Time to Trip (sec)
Time to Reset (min)
Starts Available
With External SEL-2600 RTD module All RTD Temperatures
RTD % Thermal Capacity
Courtesy of NationalSwitchgear.com
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