Schweitzer Engineering Laboratories SEL-749M - Table 4.29 Scaling of Analog Output; Table 4.30 Trip Inhibit Settings

4.32
SEL-749M Relay Instruction Manual Date Code 20080918
Protection and Logic Functions
I/O Configuration
Select LOAD_I to scale the analog output based on motor current if the output
is not of interest during overload conditions. Select either AVG_I or MAX_I
to scale the analog output based on motor current and if the output is required
during overload conditions.
Both LOAD_I and AVG_I use an average magnitude of three phase currents to
drive the analog output; MAX_I uses a maximum magnitude of the three
phase currents.
If the relay includes the voltage input option, and you select PWR_kW
parameter, the analog output full scale reference is per unit, full load apparent
power, FLVA. Equation 4.8 defines per unit FLVA:
Equation 4.8
The analog output sends real power in kW, which is always less than the full-
scale analog output (in pu FLVA) because of the motor power factor.
If the relay includes the voltage input option, and you select the PF parameter,
the analog output will be scaled using power factor. For power factors 0.8 lag,
unity, and 0.8 lead, the analog outputs will be 4 mA, 12 mA, and 20 mA,
respectively.
Trip Inhibit
(Block) Function
Table 4.29 Scaling of Analog Output
ANALOG OUT SEL
(AOPARM)
Description
Output Scaling (4 mA–
20 mA) (Unit)
LOAD_I Average Load Current 0.0–1.0 Per Unit of FLA
AVG_I Average Load Current 0.2–2.0 Per Unit of FLA
MAX_I Maximum of the Phase Currents 0.2–2.0 Per Unit of FLA
%THERM Percentage Thermal Capacity 0–100 %TCU
WDG_RTD Hottest Winding RTD Temperature 0–250 Degrees C
BRG_RTD Hottest Bearing RTD Temperature 0–250 Degrees C
PWR_kW Motor Power 0.0–1.0 per unit FLVA
PF Motor Power Factor 0.8 Lag–0.8 Lead
where:
VNOM = Nominal voltage setting
FLAn = Full Load Current setting
(n = 1 for Speed-1, or n = 2 for Speed-2)
FLVA 1.732 VNOM()FLAn• • =
Table 4.30 Trip Inhibit Settings
Setting Prompt Setting Range Setting Name := Factory Default
BLOCK PROTECT SELOGIC Variable BLK PROT := 0
CURRENT IMBALANC Y, N BLK46 := N
JAM Y, N BLK48 := N
GROUND FAULT Y, N BLK50EF := N
SHORT CIRCUIT Y, N BLK50P := N
UNDERCURRENT Y, N BLK37 := N
START INHIBIT Y, N BLK66 := N
PTC Y, N BLK49PTC := N
RTD Y, N BLK49RTD := N
Courtesy of NationalSwitchgear.com