Variable Speed Drive FAQ
(Frequently Asked Questions)
Joliet Technologies is dedicated to providing our customers and
website visitors with quality information about our products and services. As
well as helpful information you can use to make well informed decisions
regarding your drive needs.
Below is a list of questions that are common to our products and services. In
addition we will make every effort to provide hard to find information you can
use on a daily basis. If you are
looking for specific information regarding AC variable
frequency drives, DC variable speed drives and/or adjustable speed drives in
general and did not find it, let us know and we will
do our best to find it and publish it. All questions and comments are
welcome.
Q. What's the difference between a variable frequency drive
(vfd) and a variable speed drive (vsd)?
A. A
variable frequency drive (VFD) refers to AC drives only and a variable speed
drive (VSD) refers to either AC Drives or DC Drives.
VFD's vary the speed of an AC motor by varying the frequency to the motor. VSD's
referring to DC motors vary the speed by varying the voltage to the motor.
Q. What is the difference between
a VSD and a Soft Start Starter?
A. The
difference is the speed that the motor can run, when at full speed. With a
soft start starter, the motor is reduced voltage started, and then when the
motor is at full speed, or a timing circuit has timed out, a "running
by-pass contactor" pulls in and the motor continues to run at
full base speed. With a VSD (Variable Speed Drive) or VFD (Variable Frequency
Drive) (these are the same thing, just different names for the same unit),
The motor will soft
start, and you can vary the speed of the motor, by varying the output frequency
from the VSD or VFD.
So, if you don't need to vary the speed of the motor,
once the motor is up to speed, then the correct solution is a soft start starter
for that motor. If
the process requires the motor speed to vary at anytime, the correct solution
is a VSD / VFD.
The cost for a soft start starter is much less than a VSD
or VFD.
Q. Can a variable frequency drive replace a softstart?
A. Yes, a variable frequency drive can replace a soft start starter, since most drives give you a current limiting ramp to start and stop your motor. BUT, if you do not need to vary the production speed of your motor, then the soft start starter is still the correct product for the application. This is because the cost of the soft start starter is less than the cost of a variable frequency drive.
Q. Are the variable frequency drives phase sensitive?
A. No, variable frequency drives are not phase sensitive. You can adjust the direction of rotation of the motor, through the software of the drive.
Q. Can a variable frequency drive be used for a fan application, blower application or a pump application?
A. This is one of the best applications for an AC drive. In most fan/pump applications, there is a need to vary the output of the fan/pump. This is very easy to achieve with an AC drive. Plus you get the benefit of reduced energy cost of running the motor!!!
Q. How can a variable speed drive improve our production?
A. The drive can be "tuned" to the application to achieve maximum output of the equipment. Sometimes this is slightly under the base speed of the motor, and sometimes, it is over the base speed of the motor. Since every application is different, contact us through an email or the phone to discuss your application in detail and discover how we can help improve your companies' production output.
Q. Can I run a 230V, 3Ph motor with 230V, 1Ph input?
A. Yes. Joliet Technologies is pleased to announce that we have the solution to run most 230V, 3Ph motors with only 230V, 1Ph input!
Call for more information.
Q. What is the best drive for my application?
A. This is not an easy question to answer. Before we can give you a comprehensive answer to this question we will need to know more about your application and specifications. Simply call (815)
725-9696, toll free (866) 492-9888, fax (815) 725-9393 or e-mail us with your application and specifications and we will recommend the drive that's right for you.
Q. Can I convert my DC Drive application to an AC Drive?
A. Yes, You can convert your DC drive system; to an AC drive system by replacing both the motor and the drive. Consideration must be given for the torque and speed range of the DC motor, when converting to AC. You will need to
consider using a "Vector" AC drive for this conversion.
Q. Will a variable frequency drive or variable speed drive save me money?
A. Yes, the AC drive can save you money on operating cost, when the load and motor speed can be varied. By reducing the speed of the motor, you will consume less energy, which will reduce your electric bill.
Q. Should I replace my old analog equipment with new digital equipment?
A. DEFINITELY!!! For so many reasons. . . difficult and costly to get spare parts, Hard to find Tech. Support / serviceability, no communications, little flexibility, etc.
Q. Will Joliet Technologies train our staff to operate and maintain our equipment?
A. We can develop a training program that is tailored to your companies' needs and location. So, when it makes sense, we can train your personnel in our facility, or bring the classroom to your factory, for hands on training.
Q. What is a line reactor and what will it do for my application?
A. A line reactor is an impedance device. Its benefits are reduction of drive cross talk, and interference.
Input reactors will limit the waveform distortion and harmonic voltages. This will help to improve the power factor due to a reduction of the RMS currents in the system.
Output reactors are generally good up to 100 feet is distance (drive to motor). The benefits are the damping of peak voltage overshoots, which will reduce internal motor heating and lessen the "noise" that a motor can produce when it is run by a drive. On installations where the distance is greater than 100 feet, filters are recommended for motor protection.
Q. What is the best drive manufacturer for my application?
A. This
is a difficult question to answer. Our sales engineers are knowledgeable of what products are available from well-known manufacturers. They will recommend the best drive for you based on your application and specifications. There maybe several products that will meet your specifications, we will recommend the one that is best based on price and performance. Simply call (815) 725-9696, toll free (866) 492-9888, fax (815) 725-9393 or e-mail us with your application and specifications and we will recommend the drive that's right for you.
As always feel free to contact
us with any questions and/or comments you may have.
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