Functional Description
S811+ Soft Starter MN03900001E—November 2012 25
Starting/Stopping Options
The following starting options are available in the S811+ Soft Starter:
Voltage Ramp Start
This is the most commonly used mode of soft starting.
Starting at an initial value set by the Initial Torque parameter,
the voltage applied to the motor is gradually increased at a
rate that will reach rated voltage at the end of the Start Ramp
time, set by the Soft Start Time parameter. As the voltage
increases the motor develops torque that accelerates the
load toward full speed. When the S811+ senses that the
motor has achieved synchronous speed prior to expiration
of the Start Ramp time, it quickly completes the voltage
ramp and closes the bypass contactor(s).
It should be noted that a lightly loaded motor takes less
torque, and thus lower voltage and time, to accelerate to full
speed. For this case the S811+ will go into bypass before the
ramp reaches full voltage. In other words, the S811+ may go
into bypass before the Soft Start Time has elapsed.
Voltage Ramp Start
Kick Start
The Kick Start feature works in both the Voltage Ramp Start
and Current Limit Start modes. By momentarily applying up
to a two (2) second pulse of current to the motor, it provides
an initial boost in torque to overcome the static friction or
high inertial loads common in some applications. The level of
torque boost is set by the Kick Start Torq parameter and the
duration of the “kick” is set by the Kick Start Time. Setting
the Kick Start Time to 0 effectively disables this feature.
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