84 Functional Description Emotron AB 01-4429-01r2
Acceleration Time to Minimum Speed
[335]
If minimum speed, [341]>0 rpm, is used in an application,
the VSD uses separate ramp times below this level. With
Acc>MinSpeed [335] and Dec<MinSpeed [336] you can set
the required ramp times. Short times can be used to prevent
damage and excessive pump wear due too little lubrication at
lower speeds. Longer times can be used to fill up a system
smoothly and prevent water hammer due to rapidly exhaust-
ing air from the pipe system.
If a Minimum speed is programmed, this parameter will be
used to set the acceleration time to the minimum speed at a
run command. The ramp time is defined as the time it takes
for the motor to accelerate from 0 rpm to nominal motor
speed.
Communication information
Fig. 65
Deceleration Time from Minimum
Speed [336]
If a minimum speed is programmed, this parameter will be
used to set the deceleration time from the minimum speed
to 0 rpm at a stop command. The ramp time is defined as
the time it takes for the motor to decelerate from the nomi-
nal motor speed to 0 rpm.
Communication information
Acceleration Ramp Type [337]
Sets the type of all the acceleration ramps in a parameter set.
See Fig. 66. Depending on the acceleration and deceleration
requirements for the application, the shape of both the
ramps can be selected. For applications where speed changes
need to be started and stopped smoothly, such as a conveyor
belt with materials that can drop following a quick speed
change, the ramp shape can be adapted to a S-shape and pre-
vent speed change shocks. For applications that are not criti-
cal in this, the speed change can be fully linear over the
complete range.
Communication information
Default: 10.0 s
Range: 0-3600 s
Modbus Instance no/DeviceNet no: 43105
Profibus slot/index 169/9
Fieldbus format Long, 1=0.01
Modbus format EInt
time
rpm
Nom.Speed
Max speed
Min speed
[335]
[331] [332]
[336]
[341]
[343]
[225]
Default: 10.0 s
Range: 0-3600 s
Modbus Instance no/DeviceNet no: 43106
Profibus slot/index 169/10
Fieldbus format Long, 1=0.01 s
Modbus format EInt
Default: Linear
Linear 0 Linear acceleration ramp.
S-Curve 1 S-shape acceleration ramp.
NOTE: For S-curve ramps the ramp times, [331] and
[332], defines the maximum acceleration and
deceleration rated, i.e. linear part of S-curve, just as for
the linear ramps. The S-curves are implemented so that
for a speed step below sync speed the ramps are fully S-
shaped while for larger steps the middle part will be
linear. Therefore will a S-curve ramp from 0 –sync speed
take 2 x Time while a step from 0–2 x sync speed will
take 3 x Time (middle part 0.5sync speed – 1.5sync
speed linear). Also valid for menu [337], D.eceleration
ramp type.
Modbus Instance no/DeviceNet no: 43107
Profibus slot/index 169/11
Fieldbus format UInt
Modbus format UInt
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