Siemens SIMATIC S7-200 System Manual page 270

S7-200 Programmable Controller System Manual
Motor data sheets have different ways of specifying the start/stop (or pull--in/pull--out ) speed for a
motor and given load. Typically, a useful SS_SPEED value is 5% to 15% of the MAX_SPEED
value. To help you select the correct speeds for your application, refer to the data sheet for your
motor. Figure 9-4 shows a typical motor torque/speed curve.
Torque required to
drive the load
Start/Stop speed
(SS_SPEED) for this load
Figure 9-4 Typical Torque-Speed Curve for a Motor
Entering the Acceleration and Deceleration Times
As part of the configuration, you set the acceleration and deceleration times. The default setting
for both the acceleration time and the deceleration time is 1 second. Typically, motors can work
with less than 1 second. See Figure 9-5. You specify the following times in milliseconds:
ACCEL_TIME: Time required for
-
the motor to accelerate from
SS_SPEED to MAX_SPEED.
Default = 1000 ms
DECEL_TIME: Time required for
-
the motor to decelerate from
MAX_SPEED to SS_SPEED.
Default = 1000 ms
Tip
Motor acceleration and deceleration times are determined by trial and error. You should start by
entering a large value. Optimize these settings for the application by gradually reducing the
times until the motor starts to stall.
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Motor
Torque
Motor Speed
Motor torque versus
speed characteristic
Start/Stop speed versus torque
This curve moves towards lower
speed as the load inertia increases.
Maximum speed that the motor can drive the load
MAX_SPEED should not exceed this value.
Speed
MAX_SPEED
SS_SPEED
ACCEL_TIME
Figure 9-5 Acceleration and Deceleration Times
Distance
DECEL_TIME