AC Drives
AC drives, also known as variable frequency drives (VFDs), are an essential component in modern industrial control systems. These devices control the speed, torque, and direction of AC motors, which are widely used in a variety of applications such as pumps, fans, and conveyors. The use of AC drives results in energy savings, increased productivity, and improved process control. AC drives work by converting the incoming AC power into a controlled DC voltage. This DC voltage is then converted back into a controlled AC voltage to drive the motor. The control of the AC voltage results in the control of the motor speed and torque. The speed of an AC motor can be controlled by adjusting the frequency of the AC voltage supplied to the motor. AC drives use pulse width modulation (PWM) techniques to generate a variable frequency AC waveform. This waveform is then applied to the motor, resulting in the control of motor speed.
Services Offered
When it comes to AC Drives, Wistex has the knowledge and experience to best serve your VFD in your application, so it will last the best length of time and continue to perform and protect in the best way possible.
When we evaluate repairs, we consider the damaged components that need repair, as well as the MTBF for the majority of other components that would need to be serviced or replaced so that your returned unit will get the most additional runtime possible when put back into operation; plus our evaluation fee is always waived when choosing a Repair Option. If you recently purchased a VFD from us, send us your old unit and we will evaluate it for free.
We offer training for customers on all subjects motor control related such as starters, soft starters, and VFDs, and even review how to service them and keep them running for their designed lifetime. Topics can be catered to teach you on the subjects you need, or on the products you use the most. Training opportunities are offered at our facility or can be done with your team in-house.
We all know time is very important, and how much downtime impacts your industry. When it comes to selecting the right service tech to fix the problem at hand, experience is the key. Get it done right the first time, Wistex has the experience and value the importance of your time.
Frequently Asked Questions
Always by the Full Load amps of the motor, and the type of application. VFDs have ratings ND or LD (Normal or Light Duty) and HD (Heavy Duty) both of which are key to figuring out sizing. Typically 110-120% overload in a light duty or normal duty, and 150-180% overload in a heavy duty application.
- Speed Control of an AC synchronous motor, as well as direction control
- Under speeding or over speeding a motor
- Running in a current limiting mode to protect a motor
- In some approved applications, you can use a VFD to take single phase input, and convert it to three phase, all while controlling the voltage and frequency output
Primarily it is a Diode Bridge Rectifier setup to convert the AC coming in to DC, where it stores the DC in Capacitors and pulls from the capacitors through IGBTs (insulated gate bi-polar transistors) converting the DC back to AC in a controlled PWM (pulse width modulated form.)
If you want piece of mind in knowing your motor & system is setup correctly, start-up by a Wistex professional tech is highly recommended. Ensuring the best level of protection, without the nuisance trips, or having a system automatically reset at times are just the few considerations to take in order ensure your soft start & VFD are configured to your systems' needs..
When an authorized company and technician working on your VFD or Motor Control performs the start-up and fills out the appropriate paperwork with the Manufacturer, your warranty is extended. Typically manufacturers of VFDs or Soft starters offer a warranty of 18 months from shipment, or 1 year from date of install, whichever occurs first. If the start-up is certified and warranty paperwork is filed, the date can be extended to 2-3 years overall depending on the manufacturer.