Mm440 drive speed vary

[deno]

Sir,
I have Siemens mm440 drive .which is using for conveyors .it's speed is controlling through pot (analog input 0-10 volt)
But i am facing problemfrom some days that my drive referance speed is automatic increase when the connected all 8 motor are take it in line
But the same drive are working ok when we run 7 motor .
It will happened any of one motor
Please help

 

[deno]

Have any body idea of the same problem

 

[osmanmom]

post your analog wiring for "pot (analog input 0-10 volt)"

 

[deno]

Drive terminal analog wiring(pot wiring)as below
1-+10volt
2&4short -0 volt
3-pot resistance change leg

 

[danatomega]

Sounds like you could be suffering a voltage variation when eight units are connected. Have you monitored the voltage levels at the terminals?

I guess I'm a little confused. Do you have 1 pot connected to all the drives or 1 pot for each drive?

 

[deno]

Hi,
Danatomega
Sir,
Have you talk about analog voltage ?
And second we have sperate pot for each drive for singal running .and one comman pot for United running.

Here the problem is occurring only one drive only when we connect 8 th motor .

 

[danatomega]

Well, I guess there are two voltage questions.
1) Have you monitored the line voltage supplying the VFD drives?
2) Have you monitored the analog voltage at the speed reference terminals (pins 3 & 4)?

Now I'm not sure how it is that you use a separate pot for each VFD -AND- one common pot for the united running.
And what is the wiring when using the unified method? One VFD is supplying the +10 VDC output voltage to feed the pot and all the analog commons (pin 4 (and 2)) are tied together? Do you use relays to switch out the individual pots and switch in the united pot?

 

[deno]

Hi,
Yes i have measure line voltage it is 415-420 volt
And not measure analog voltage because i think that if it analog voltage problem than why drive speed increase when we connect any of 8 motor of particular drive.

 

[danatomega]

Well, I don't know and you don't know why the drive speed increases when you connect 8 drives - that's why I asked if you had done any measuring / monitoring of the voltages.
If you're not going to do some testing, then you will simply continue to guess at why does it do it, and I can't help.
I also asked how is your connections when using a united pot because that may provide a clue as to why your system does what it does. Without some information, I don't see how you expect help.

 

[tarik1978]

please post a wiring diagram so we can help

 

[osmanmom]

how much the speed increase 10%,20%,50% ?

 

[deno]

Sir ,
I have checked the analog voltage accross the 3&4 terminal its not varry.
And speed of drive increase upto 50hz (maxspeed)
Here i have again clear that there is not 8 th drive it's motor .
For example we have 6 driveto run 6 zone & each have 8 motor connectted.when we run conveyors in united mode all 6 drive are run at same speed .
Now the problem is my 5th no drive .which create problem when it we Connet 8 th motor .only it's speed is increase other drive are running on set speed but 5 no drive speed increase and goes up to 50 hz.

Sir
I think problem is like some thing called field weakend .
Please guide

 

[osmanmom]

draw you motor layout

 

[danatomega]

Are you running 8 motors on a single VFD? And are you connecting and disconnecting motors from that single VFD?

 

[deno]

Hi
Yes 8 motor are running at 1 vfd and having mpcb
Protection of each motor when we on 7 mpcb on drive work ok but when we on 8 th mpcb drive speed increased .it will happen any of one motor