Schweitzer Engineering Laboratories SEL-701, Instruction Manual

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701 Motor Protection Relay
Date Code 20010719
Settings Calculation
Basic Motor Protection
4.26
Load-Loss Elements
Load-Loss Element, No Voltage Option (Relay Models 0701000X & 0701010X)
Table 4.17 Load-Loss Element Settings, No Voltage Option
When the relay is not equipped with optional voltage inputs, the load-loss
detection function is dependent on current alone. The relay arms the load-loss
detection logic a settable time after the motor starts, as defined by the Load Loss
Starting Time Delay setting. Set this delay to allow pumps or compressors to reach
normal load. Once armed, the function issues an alarm or trip if phase current drops
below the alarm or trip threshold for the specified time delay.
Set the Load Loss Trip and Alarm thresholds greater than the expected motor no
load current but less than the minimum current expected when the motor is operating
normally. These settings are entered in per unit of the Full Load Amps (FLA) setting.
If you expect the motor to operate at no load normally, disable this function by
setting LLAPU equal to OFF. The relay automatically hides the remaining load-loss
settings.
Load-Loss Element, Voltage
Option Included (Relay Models 0701001X & 0701011X)
Table 4.18 Load-Loss Element Settings, With Voltage Option
Table 4.17 Load-Loss Element Settings, No Voltage Option
Setting Prompt
Setting Range Setting Name =
Factory Default
Load Loss Alarm Threshold OFF, 0.10–1.00 pu FLA LLAPU = OFF
Load Loss Trip Threshold 0.10–1.00 pu FLA LLTPU = 0.50
Load Loss Starting Time Delay 0–15000 s LLSDLY = 0
Load Loss Alarm Time Delay 0.00–400.00 s LLADLY = 5.00
Load Loss Trip Time Delay 0.00–400.00 s LLTDLY = 10.00
Table 4.18 Load-Loss Element Settings, With Voltage Option
Setting Prompt
Setting Range Setting Name =
Factory Default
Load Loss Alarm Threshold OFF, 30–2000 W
a
LLAPU = OFF
Load Loss Trip Threshold 30–2000 W
a
LLTPU = 0.50
Load Loss Starting Time Delay 0–15000 s LLSDLY = 0
Load Loss Alarm Time Delay 0.00–400.00 s LLADLY = 5.00
Load Loss Trip Time Delay 0.00–400.00 s LLTDLY = 10.00
a
Setting range shown for ITAP = 5 A. Range is 6–400 W when ITAP = 1 A.