OPERATION
Timed Voltage Ramp
Timed voltage ramp (TVR) soft starting ramps the application of voltage to the
motor over a defined time period. The voltage ramp reduces the initial starting
torque and slows the motor's rate of acceleration.
TVR starting can be useful for applications where multiple motors of different sizes
are connected in parallel, and/or the loads are not mechanically linked.
NOTE
For multiple motors of the same sizes, and/or mechanically coupled loads,
use constant current starting.
NOTE
TVR soft starting is not suitable for high inertia loads (such as fans), which
require a high level of voltage to accelerate the load.
For a timed voltage ramp start, the following are typical values and can be adjusted
to suit your specific application:
•
Add the FLC value of all the connected motors. Use this combined value
to set parameter 1B
Motor Full Load Current
. (Note that the combined
value must not exceed the starter rating.)
•
Set parameter 2C
Initial Current
to 100%, parameter 2D
Current Limit
to
500%, and set the ramp time as required (parameter 2B
Start Ramp
Time
).
3
6
5
4
2
1
1:
Initial Current
(parameter 2C)
2:
Current Limit
(parameter 2D)
3:
Start Ramp Time
(parameter 2B)
4: Full voltage
5: Motor 1 current
6: Motor 2 current
Time
Adaptive Control for Starting
In an adaptive control soft start, the EMX4e adjusts the current in order to start the
motor within a specified time.
NOTE
The EMX4e will apply the current limit on all soft starts, including adaptive
control. If the current limit is too low or the start ramp time (parameter 2B)
is too short, the motor may not start successfully.
EMX4e User Manual (710-18433-00C) |
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