using AB Powerflex as a third phase for 3 phase 230V motor !

leonlai

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Join Date
Jun 2011
Location
WA
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96
Folks,

Where I work we have a 230V 1 phase supply and Motor is 3 phase 230V. We connect an ac single phase powerflex 70 and let it produce 3 phase to the motor. Everything work well except :
Motor is running forward, then we change State the VFD from Run to Stop then Run, every 2 cycle like this, Motor run Reverse. Then we change the state again, Motor run Forward !?

I set the current level is about 1.5 of rating Amp of the motor and hopefully with won't cook the VFD if motor is stall of lockout

Any idea what's going and how can I fix this !?

Thanks
 
Just to clarify: all three phases from the PowerFlex 70 are connected to the motor, correct ? You aren't really attempting to feed different phases of the motor from different sources, are you ?

I think that you are suspecting that the drive is somehow switching phases and therefore switching directions.

This is very, very unlikely. All AC drives rectify the incoming voltage to DC, then create a synthesized AC sine wave to run the motor. The order of the incoming phases does not matter.

What is more likely is that you are inadvertently giving the drive the wrong direction command.

Is the drive controlled over a network, or via discrete inputs ?

Is the drive supposed to run in Reverse, ever ?
 
Al lot of drives will allow you to run a 3 phase motor from a single (2) phase supply.
Usually L1 and L2 are used and the drive has to be set up to ignore phase loss or how ever the manufacturer specifies.
I have use many of the PLC direct drives for this. The 120 input drives will output 220 3 phase and work fine on small motors.
The drive is usually derated due to the missing phase. The motors will run normally in forward and reverse.
I don't know if the AB drive you have selected will do this, but a quick check on the specs should tell you.
This is a pretty good way to put a variable three phase motor on some small metering pumps which is the application I have used the most. Works pretty good with the 4-20 ma. output varying the dosing as required.
How are you turning the drive on and off? as to why your drive reverses I haven't a clue. Are you hardwire switching?
If so you can select three wire with enable, run forward and run reverse and don't close the reverse contact?
 
Last edited:
You probably have the Flying Restart feature enabled, but don't need it for your load. Disable it. On the PF70 it is probably Parameter 169. The factory default is 0 for "Disabled", so someone must have enabled it by changing that yo 1.

It is there to accommodate a load that might already be spinning when you give the VFD a Run command, so that the drive doesn't attempt to bring the speed to Zero before accelerating it. That works great, but the drawback is if the motor is NOT spinning, it sometimes makes it run in reverse for a second or two to find out. So if your load is NEVER going to be spinning, disable that feature. people often enable it because they don't understand what it's for, but think they need it. most people do not.

If it MIGHT be spinning and someone deliberately WANTED this feature, then try adjusting the Gain setting, parameter 170, to make it more predictable.

Or just understand and live with the little reverse tweak it does sometimes.
 
It's a Powerflex 70.
I wired as instruction 3 wire control Start/Stop
Feed 230V 1 phase to Powerflex
Powerflex feed 230V 3 phase to an actuator (not a motor, my bad)

Drive does not connect to any network and not to any PLC,
But I do set parameter like ab instruction for 3 wire Start/Stop !
http://www.ab.com/support/abdrives/powerflex70/pfwiring/3_Wire-Start_Stop.pdf

Just plain power supply to drive and to actuator !

Like I states in last post, Everything run OK, then I hit Stop and hit Run again (button on the drives), first STOP-RUn go Forward like normal, then Stop-Run agian the actuator run backward ! Stop - Run again 2 times then Actuator run Forward like normal !


I'll check the parameter like jraef said, but the actuator control a running flow right now so I dont know when I can check it yet !

Any idea I'll write down and test at a same time !

Will let folks know the results
 
The flying start enabled thing can and often will cause the motor to start up in the wrong direction if it "thinks" the motor is already turning that direction. It should then ramp down and correct itself if you let it go that way long enough. Some applications will break stuff before that can happen. I concur with the advice to disable flying start.
 
Instead of starting and stopping with the buttons on the drive try using the stop / start buttons added for the three wire control.
 
Yes, the little direction button on the VFD is easy to hit by accident and reverse the direction.

If you always want the motor to run forward, and you want to run it from the keypad and/or the remote wiring, you should set the parameter to disable reverse.
 
leonlai,

You can view the parameter values on the HIM while the drive is active. Unless there is some safety restriction preventing you from getting close to the drive while the motor is running, you shouldn't have to wait until it's off.

You are sort of repeating yourself without answering some of the important questions being asked. The first question was what is the Catalog Number of the PowerFlex 70 drive you are using? It is not always vital to give this info but it can be, depending on the specific issue at hand.

Next question - is the drive supposed to run in reverse ever? I would guess, as you've mentioned the motor is being used as a "flow actuator" that it is not. Also, because you only have it wired for Stop/Start and not Fwd/Rev. Either way, can you please confirm this? Also, if it is not normally commanded to run in reverse, can it actually turn in reverse of its own accord, as in freewheel.

The Flying Start feature - I would agree, if the motor cannot turn in the forward direction of its own free will, then you would be better off disabling this feature. However, if it can freewheel, or be restarted before coming to a standstill, then this feature is best left enabled. As jraef stated, it is not on by default, so "someone" would have had to have enabled it, if it is indeed already enabled.

A drive will normally start with a speed reference of 0Hz and then ramp up to the setpoint speed reference. This is fine when the motor is at a standstill. You have 0Hz and relatively low current at startup.

Where you have a motor that is already spinning, the initial 0Hz speed reference can act to brake the spinning motor, which can exert huge forces on the mechanics of the application. With 0Hz and initial rotation, larger currents are generated. This scenario is not good for the motor and its coupling and is also not good for the drive.

The Flying Start feature is designed to prevent the drive from issuing the normal 0Hz speed reference at startup when a motor is already spinning. The Flying Start can sweep in a positive and negative direction until it "finds" the motor i.e. matches its speed (Hz) and voltage (phase). Once they are synchronized, the drive can then command the motor to the speed reference and resume normal control.

By the way, another thing you have not mentioned so far is what and where is the speed reference coming from?

If your motor is reversing, while Flying Start is enabled, and you know the motor is never commanded for reverse, then the normal procedure where Flying Start is to be left enabled, is to set...

P190 [Motor Direction]= 2 "Reverse Disabled"

(The default is = 0 "Unipolar")

This means that the direction is no longer changeable from any source, including the Flying Start feature. It will now look for the spinning motor on a positive sweep only.

This configuration is based on the fact that you know you are not commanding a reverse direction, and you know that the motor application cannot freewheel in the reverse direction of its own free will, prior to startup.

That is one possibility here.

Once we know more on those parameters we'll have more to chew on.

Regards,
George

Here's a couple of shots of a PowerFlex 700 I just viewed the parameters on while running...
PowerFlex_7_Class_View_Parameters_While_Running.jpg


Regards,
George
 
Update:

It's a Powerflex 70: 20A B 9P6 C 3 AYNNNC0 Ser A
Flying Start was disable
Reverse was disable
Stop and Run VFD, actuator run reverse, stop and Run VFD again, actuator run forward.
Set Flying Start to enable ---> deep fry 2 fuses in the Actuator ---> waiting for parts now !
no clue >_<
Any one has explanation why it deep fry 2 fuses in the Actuator when I set Flying Start enable ??
 
Update:

It's a Powerflex 70: 20A B 9P6 C 3 AYNNNC0 Ser A
Flying Start was disable
Reverse was disable
Stop and Run VFD, actuator run reverse, stop and Run VFD again, actuator run forward.
Set Flying Start to enable ---> deep fry 2 fuses in the Actuator ---> waiting for parts now !
no clue >_<
Any one has explanation why it deep fry 2 fuses in the Actuator when I set Flying Start enable ??
Wait, you have fuses down stream of the VFD output??? Bad idea.
What else are you not telling us!
 
Are you starting and stopping by cutting power to the drive and not by enabling and disabling the controls to the drive?
Flying start is not an issue if you use the drive properly and let it do the work.
 
Why not just give us a sketch as to your connections and some details on the 'actuator' it would save alot of time and trouble.

Steve
 
redbarron55 was right, it was cut power from drive which cause fuse blown in actuator
I was use Powerflex 70: 20A B 9P6 C 3 AYNNNC0 Ser A
230V 1 Phase supply to Drives, gives out 230V 3 Phase to

Power flex wired as 3 wire Start/Stop Drive supply 24V logic power

AUMA MSP1A1700-2F4JE1-KMS-TP104-241
http://s15.postimg.org/6uk5skp4r/AUMA_Actuator_Wiring_MSP1_A1700_2_F4_JE1_KMS_TP10.jpg

setting 190 = 2 disbale - 169 flying start disable
problem: random direction when start button is pressed while arrow show forward !
 

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