VFD control

[drewski]

Hi everybody,

I have a question. How would you select a VFD and how is the VFD controlled ??????? I tried lookig it up on the internet, but it confused me even more.

 

[benaround]

You can't ask the people that you work with this type of question ? I get questions all day

long from the newer guys, how else will they learn.

 

[sii]

Hi everybody,

I have a question. How would you select a VFD and how is the VFD controlled ??????? I tried lookig it up on the internet, but it confused me even more.

You're going to have to be a little bit more specific than that if you want constructive answers.

 

[a.bisnath]

basics of selection

basics of selection

type of load inductive or non-inductive
voltage current and horsepower of load
if motor inverter grade windings and motor cable preferable or input /output line filters may be needed (reactors/snubbers)
controlled by many ways push-button,rotary dial potentiomer ,4-20 mA ,plc dcs ,ethernet/computer interface giving hand control or controller set point(auto),it can be controlled over the internet if you want,its amazing what networks can do now
the Danfoss brands are very good also are Allen Bradley and Siemens check the websites

 

[Jraef]

No offense, but selection of a VFD is something best left to people with training. One of the biggest problems is people picking them out thinking they are no different than picking out a motor starter, or worse yet, allowing a vendor who knows even less to pick it for you. Lots and lots of pitfalls.

But to address your basic issues, a VFD is selected via the following at a minimum (the real list is too long).
Motor size (power) and voltage
Motor type
Type of load, i.e. Constant Torque or Variable Torque
Starting requirements (long list)
Stopping requirements (long list)
Control interface requirements (long list)
Mounting environment
Motor protection requirements
Accuracy requirements, i.e. Speed, Torque, Repeatability
Load step change response capability
Communications capability
Available assistance from a supplier (often neglected until you need it)

 

[a.bisnath]

I do agree

I do agree

many of these parameters and more are found in the vfd manual which is usually downloadable from the site,It is amazing to see the amount of features these units come with making them very flexible and multipurpose to many conditions and also explanatory to class and division of the location it is to sited,selection indeed should be left to an engineering or authoritative(subject matter expert) person for selection,i have even built them from scratch with individual components based on my knowledge and training.i may have assumed wrongfully

 

[abrownpe]

Simple form: VFD selection is based on motor voltage then motor hp, then function (ie variable torque/constant torque) all from the manufacturers data sheets. Finally environment (ie temperature).

Standard controls are in order of popularity:
4-20ma
0-10v
manual (with speed adjust set and then use a single contact to energize)

Newer applications included control with modbus, data highway, ethernet.

I'm leaving out a lot but this still covers 90%.

Albert S. Brown Jr PE

 

[TxEngr]

As you can see from the responses, you've asked a simple question for which there is no simple answer. One source of information I would recommend is the Allen Bradley Drives Engineering Handbook which is available for download off of their site. Just do a Google search for "AB Drives Engineering Handbook" and it should show up. It's not easy reading but should help you understand better. It also covers both AC and DC drives and some specific applications.

edit... Here's the link http://literature.rockwellautomation.com/idc/groups/literature/documents/at/drive-at001_-en-p.pdf

TxEngr