Controlling Variable Frequqncy Drive?

[KNRO]

I'm considering Toshiba VFnC1 VFD for my 3-phase induction motor. It talks a bit about RS232C serial communication, but beyond a couple of liners, no details are given in the PDF.

From the manual, I can see that you can control the frequency via 0-10 VDC analog input that correspond to the 0-50 Hz range. How about other functions like acceleration/deceleration? Reverse direction? Start/Stop..etc? Is there a "standard" way of performing these functions among VFDs? How do I "command" the VFD to perform these functions _remotely_ via a signal?

Your help is appreciated!

[Al_The_Man]

Originally Posted by KNRO From the manual, I can see that you can control the frequency via 0-10 VDC analog input that correspond to the 0-50 Hz range. How about other functions like acceleration/deceleration? Reverse direction? Start/Stop..etc? Is there a "standard" way of performing these functions among VFDs? How do I "command" the VFD to perform these functions _remotely_ via a signal?

These functions are set by parameter setting and physical inputs, i.e. you set the VFD to external control and inputs control the fwd/rev and ±10vdc controls the speed, either by analogue output from a CNC or a simple potentiometer.
The accell/decel is set by parameters. Many VFD's have the capability of self tuning for the motor you are using.
You can also set the maximum frequency higher than 50 or 60hz, e.g. 120Hz for a 4 pole motor, therefore doubling the base speed.
But if the motor is presently a 2 pole motor, and not inverter rated, it may be unwise to run above the base speed.
If integrating a VFD into a CNC machine for ±10vdc analogue control, it is preferred to set an output for a zero speed and a up-to-speed output to the CNC.
Al.

[TOTALLYRC]

Originally Posted by KNRO I'm considering Toshiba VFnC1 VFD for my 3-phase induction motor. It talks a bit about RS232C serial communication, but beyond a couple of liners, no details are given in the PDF. From the manual, I can see that you can control the frequency via 0-10 VDC analog input that correspond to the 0-50 Hz range. How about other functions like acceleration/deceleration? Reverse direction? Start/Stop..etc? Is there a "standard" way of performing these functions among VFDs? How do I "command" the VFD to perform these functions _remotely_ via a signal? Your help is appreciated!

Al has it right, but I thought I would add a few things.
If you are not running it cnc and are adding this to a manual machine, you can set up a nice little control box with af wd and rev switch plus a pot for speed control. Many VFDs don't like it if you use the old forward and rev switch to change directions when running.
The manual will have all the settings for accel and stuff. My manual is 100+ pages and can be slow going at times.

Mike

P.S. On a cnc application an up to speed output is very important as Al says. Mine right now takes 8 seconds to get to full speed. Until I finish the wiring and just for testing purposes, I have an 8 second spindle start delay programed into Mach3.
But the input to mach from the drive saying that the drive is up to speed will prevent any chrashes if there is a spindle problem.

[KNRO]

Thanks Al & Mike for the replies. I'd like to be able to control the VFD from a PC, and I already have a stocked TTL level card can be installed (5VDC), but it's digital I/O only. Are they any VFDs that work on the TTL level?

After reviewing two VFDs, it looks like that I have to use a pot for speed control in some models and 0-10 VDCs at others. There is more circuitry needed for direction and start/stop.

[Al_The_Man]

Some VFD's have the capability of 0-10v and you use a single input to indicate fwd/rev.
There are others that have the option of ±10vdc, but both would need an isolated PWM to analogue converter from the likes of Mach systems etc.
With other PC systems, it is possible to use a analogue card for control.
Both types of analogue inputs require a start input, but the 0-10v also requires the fwd/rev input.
You can get some that will communicate over a bus such as Modbus, or similar for control, but they are not common.
Al.

[KNRO]

Some VFD's have the capability of 0-10v and you use a single input to indicate fwd/rev.

Can you suggest any known VFD brands which support this? Regarding the "start input", when the VFD is outputting 0 Hz, this will make the motor stop? and the motor will spool up as you increase the frequency, and you can stop it again by dropping the VDC to 0? Or is the 0-10VDC just for speed control and there is another input for start/stop?

[Al_The_Man]

With a potentiometer input once the start input is made, the potentiometer will obviously vary the speed from 0, or whatever the minimum rpm is set to, to maximum rpm, as long as the start input is made, the VFD is always active.
So for example, say the potentiometer was set for mid range and the start input was initiated, the motor would accelerate at a pre-programmed rate up to the rpm that corresponds to the pot set point.
IOW, the VFD analogue input is not enabled until the start command is given, regardless as to the analogue voltage in.
For the 0-10v input, this is usually the default feature, the ±10vdc analogue is often an added extra, not always available in most types.
Al.

[TOTALLYRC]

Originally Posted by KNRO Thanks Al & Mike for the replies. I'd like to be able to control the VFD from a PC, and I already have a stocked TTL level card can be installed (5VDC), but it's digital I/O only. Are they any VFDs that work on the TTL level? After reviewing two VFDs, it looks like that I have to use a pot for speed control in some models and 0-10 VDCs at others. There is more circuitry needed for direction and start/stop.

If all you have is ttl outputs and don't have 0-10v analog there is one other alternative. My Hitachi allows for I think 6 preprogramed speeds via which inpu is active. You would have to downlaod the manual from their website for all the details. While it might not be as good as full variable speed, it is better than single speed.

The sj200 series by Hitachi supports multiple interface protocals including 0-10v analog and works well with mach3. It is also sensorless vector meaning it devolopes low speed torque much better than a Volts/Hertz drive.

http://web3.automationdirect.com/adc/Home/Home has a decent selection of drives.

There are a whole bunch more manufacturers out there. I picked up mine, a Hitachi, 1 phase input 3 phase output sensorless vector #hp Brand new in box for $300 on ebay. My only regret was not having enough money to by both of the ones he had for sale.

The way my controller work is that if you input an Speed command, you will get the coresponding voltage on the 0-10v wires. The drive ignores this signal until the forward or reverse input is present.
There is one thing to remember, and it caught me by surprise the first time it happened. When setting up the VFD, I put in a minimum rpm value. When you input a forward or reverse command, the motor goes to min speed, even with 0 volts on the analog input.
I would say most vfd incorporate at least 0-10v analog input as this has been an industrial standard for many years.
I know that hitachi does, plus ssd/eurotherm and reliance, as we use them at work.
I would have gone with ssd/eurotherm as I have the programing software and cable here at work, but I couldn't find what I wanted at a price I could afford/was willing to pay.

Mike.