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S3 PROTECTION
6–68
START PROTECTION
Range: Off, On, Contact Input 1 to 10, Virtual Input 1 to 32, Remote Input 1 to 32, Logic
Element 1 to 16
Default: Off
By setting the START PROTECTION setpoint to OFF, Start Protection can be disabled.
Thermal protection will therefore go directly to the running condition and the Thermal
Overload Curve will be employed to protect the connected load.
LOCKED ROTOR CURRENT
Range: 2 to 11xFLA in steps of 0.1xFLA
Default: 6xFLA
This is the steady state motor current with the rotor locked, when supplied from a source
at rated voltage and frequency.
SAFE STALL T COLD
Range: 1.0 to 600.0 sec in steps of 0.1 sec
Default: 10.0 sec
This setting is given as the Safe Stall Time Cold.
THERMAL O/L CURVE
Range: Standard, FlexCurve
Default: Standard
CURVE MULTIPLIER
Range: 1 to 15 in steps of 1
Default: 4
Fits the Standard Overload Curve to the thermal characteristics of the protected motor.
THERMAL O/L PKP
Range: 1.01 to 1.25xFLA in steps of 0.01xFLA
Default: 1.01xFLA
The Thermal Overload Pickup setting defines the current level at which the motor is
considered to be overloaded. The Overload Curve is cut off at current values below this
pickup value. Normally, the Thermal Overload Pickup Setting is set slightly above the
motor Service Factor, to account for inherent load measuring errors (CTs and limited
relay accuracy). The typical total inaccuracy factor is 8 to 10%; as such, for motors with
a thermal capability at rated service factor of 1 or 1.15, the Thermal Overload Pickup
level should be set as 1.10 or 1.25, respectively.
The Thermal Capacity Used value decreases exponentially when the motor equivalent
current (I
) is less than the Thermal Overload Pickup setting.
eq
UNBALANCE K FACTOR
Range: 0 to 19 in steps of 1
Default: 0
Sets the degree of unbalance biasing used by the Thermal Overload Curve. Zero
disables the unbalance bias.
COOL TIME RUNNING
Range: 1 to 1000 min in steps of 1 min
Default: 15 min
Sets the Cooling Time Constant used by the Thermal Overload Curve when the motor is
in service. Enter the time in minutes for the motor to cool by 63% of the difference
between the initial and ambient temperature when the motor is running at rated speed.
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS
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