
VMX
2
Series Digital Solid State Soft Starter User Manual
71 |
P a g e
Appendix 1 - Ramp Profile Details
The
VMX2 Series
offers four different types of starting ramp profiles.
Simply select the one that best matches your motor / load requirements.
In addition,
two separate ramps
are available that can be selected via
contact closure (see section 4.2.5.a), and each one can be set up for
any ramp type as shown in the table below.
Following are descriptions of the four types of Ramp Profiles
1. Voltage Ramping
is the most reliable starting method, due to the fact
that at some point the starter will reach an output voltage high enough
to allow the motor to draw full current and develop full torque. This
method is useful for applications where the load conditions change
frequently and significantly enough to require different levels of starting
torque. Examples where this is effective are:
▪
Material handling conveyers
▪
Positive displacement pumps
▪
Drum mixers, grinders etc.
Voltage is increased from a starting point (Initial Voltage) to full voltage
over an adjustable time period (Ramp Time). To achieve Voltage
Ramping, set the Ramp Profile (F010) to 0001 or 0003 (Voltage Ramp),
and the Maximum Current Limit setting (F014) to maximum (600%).
2. Voltage Ramping with Current Limit
works similar to mode 1,
except this mode adds an adjustable maximum current output. Voltage
is increased gradually until the motor current reaches the Maximum
Current Limit setting (F014). The motor current is held at this level until
the motor accelerates to full speed. When the motor current drops
below the limit setting, the output voltage is automatically increased until
the
VMX2 Series
is At-Speed. This may be necessary in applications
where the electrical power is limited. Examples would be:
▪
Portable or emergency generator supplies
▪
Utility power near the end of a transmission line or other starting
power demand restrictions.
Using Current Limit will override the Ramp Time setting if necessary, so
use this feature when acceleration time is not critical. The Ramp Time
setting; however, still determines the slope of the ramp up to the Current
Limit setting to apply the softest possible acceleration. To achieve
Voltage Ramping with Current Limit, set the Ramp Profile (F010) to
0001 or 0003 (Voltage Ramp), and the Maximum Current Limit setting
(F014) to a desired lower setting, as determined by your application
requirements.
Ramp 1 Settings
“Ramp Type
Selection”
from F010
Ramp 2 Settings
Ramp
Type
Initial
Torque
from…
Ramp
Time
from…
Current
Limit
from…
Ramp
Type
Initial
Torque
from…
Ramp
Time
from…
Current
Limit
from…
Voltage
F011
F013
F014
1
Voltage
F015
F017
F018
Current
F012
F013
F014
2
Current
F016
F017
F018
Voltage
F011
F013
F014
3
Current
F016
F017
F018
Current
F012
F013
F014
4
Voltage
F015
F017
F018
Table APP 1.1: Ramp Selection Choices and Settings
Initial Torque
Full Speed
V
o
lt
a
g
e
Time
Figure APP 1.2:
Voltage Ramp with Curre nt Limit
Ramp Time
Curre nt
Limit Se tting
Initial Torque
Full Speed
V
o
lt
a
g
e
Time
Figure APP 1.1:
Voltage Ramp w/o Curre nt Limit
Ramp Time