Eaton S801+ Series, User Manual

Page: 32 / 68

Functional Description
S801+ Soft Starter
MN03900002E—November 2012 www.eaton.com
21
Starting/Stopping Options
The following starting options are available in the S801+ 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 S801+ senses that the
motor has achieved synchronous
speed prior 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 S801+ will go into bypass before the
ramp reaches full voltage. In other words, the S801+ 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.
Initial
Torque
Kick
Start
Torq
Kick Start Time
100%
Bypass Bypass
Voltage
Ramp
Rated
Voltage
Soft Start Time
tr
Start Run
T
orque
Time (Seconds)
100%
Start Run
Speed
Time (Seconds)