S811+ Operating Configuration
S811+ Soft Starter MN03900001E—November 2012 39
Thermal Overload
The S811+ Soft Starter features an electronic motor overload
protection feature. It is designed to protect the motor and
power wiring against overheating caused by operating at
excessive current levels for extended periods of time.
Entering the motor’s full load current rating, using the Motor
Nameplate FLA parameter programs the overload. The Motor
Nameplate FLA is settable from 32–100% of the S811+’s
rated current (frame size).
The overload’s trip class (default = 20) is set in the Ovld Trip
Class parameter in the Soft Start Config Menu.
Thermal Overload may be disabled during the Voltage Ramp
or Current Limit start ramps (default = Enabled) by disabling
the Overload on Start parameter located in the Protections
menu. Disabling this protection parameter is not
recommended.
Additional details on the Thermal Overload can be found in
Appendix B.
Soft Start Configuration Application Notes
a) Voltage Ramp Start Configuration
Default values may be used for Start Time and Initial
Tor q ue.
Kick Start Torque = 0% (fans and pumps), 75% (high
breakaway loads)
Kick Start Time = 0 sec (fans and pumps), 1 sec (high
breakaway loads)
Start the motor and determine the worst case starting
conditions. Adjust Initial Torque for smooth start without
hesitation. Motor rotation should begin within 2 seconds.
If Stall Faults occur at the end of the ramp time, increase
Initial Torque, Kick Start Torque and Time and/or Soft Start
Time to get into bypass before the Soft Start Time
elapses. Also, verify that the motor is not overloaded.
b) Current Limit Start Configuration
Initial settings:
Initial Torque = 50%
Soft Start Time = 60 sec
Kick Start Torque = 0%
Kick Start Time = 0 sec (disabled)
c) Start the motor and determine the worst case starting
conditions. Adjust Initial Torque for smooth start without
hesitation. Rotation should begin within 2 seconds and
the motor should smoothly accelerate to full speed.
d) If Stall Faults occur, increase Initial Torque and/or Soft
Start Time to get into bypass before the Soft Start Time
elapses. Also, verify that the motor is not overloaded.
Verify that the motor is not in a stall condition. A stall
condition will be noted when the motor does not
continue to accelerate during the start ramp.
e) After suitable performance has been achieved,
determine the starting time to bypass and set Soft Start
Time at 1.25 times this time. For example, if it takes 10
seconds to accelerate the motor and go into bypass, set
the Soft Start Time for 12.5 seconds. Adjust the Soft
Stop Time for the desired stopping time.
f) The Initial Torque setting is adjusted to achieve motor
rotation within 2 seconds of motor energization. The
Initial Torque value also determines the upper limit of
applied current during a Current Limit start.
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