Hi guys

There are plenty disussions regarding this fault ((7901) but I can not find the answer anyway

I have G120C PN 7.5 kW and it Controls a motor for hydraulic Power pack.

Motor rates are: 7.5kW, 14.7A, 1400RPM, 400VAC, 50Hz

I use Encoderless speed Control

Pump works like this: I send a start signal and it goes to full speed after that I can open or Close spesific valves to move some auxilaries. When I Close a valve so come Overspeed. I can understand that because during valve closing RPM goes up  and load decrease (there is no any accumulator in hydraulic system).

I set P1082 to 1700 RPM, P1470 to 7 and P1472 to 200 ms and pumps works very well upto 1200RPM( no overspeed) But if speed increases to 1400 RPM it can give overspeed sometimes.

May be you can recommend some more parameters I can try to improve my pump?

Hello

I will try to  increase P1082 to 2000 RPM and test it.

I Think it is possible to change P1082 online without motor init.?

But if it does not work due to oil pressure behaviour I will probably change to V/F Control.

Thanks

Will test tomorrow!

Hi

So I finally chose U/F Control because it was not possible to use Speed Control  with such  oil pressure behavior.

But I have Another question regarding holding torque (magnetization). When I send 0 speed to the drive it ramps down as normal  but I do not remove OFF1 and Enable operation signals so the motor is always  magnetized. Would you suggest to remove Enable operation signal to avoid motor temperature raise during standstil?

Because with both these signals on  and speed setpoint 0 rpm FC gives 15V and 9A output to the motor which cause the temperature raise.

I left Enable operation on due to specifics of operation but I see that without external cooling it will not work

Yurius,

from my experience, using "zero" speed and leaving enabled the drive is always a bad bad idea. The temperature can raise, of course, but anyway it is wrong to use a zero speed... Inverters are not servo drives, they do not have feedback and, so, since V=0 means that the axis is stopped, I strongly suggest to you to disable the inverter. Also check the temperature when it runs continuously at low speed, because the temperature can raise and the ventilation of the motor can be insufficient (thus requires an external cooling source)

Thanks Davinator

I monitored the temp in workshop and it was Rising reletively fast, so I will disable Enable signal when motor is in standstill.

Normally I operate the motor on high speed so there is enough cooling.

Thanks again for your answer

Yurius

Thanks Davinator

I monitored the temp in workshop and it was Rising reletively fast, so I will disable Enable signal when motor is in standstill.

Normally I operate the motor on high speed so there is enough cooling.

Thanks again for your answer

 hi guys,

i have same issue with sinamic s120  cu310-2dp, p1300=20 sensorless vector,

when speed increase overspeed fault comes,

i use it on elevator ,

with low speed issue reduced , but speed is less than normal,

i did stationary autotune only, i think may be need activate autotune with motion sensorless ,

please advise for solution,

mahhamadd

 

Yurius

Thanks Davinator

I monitored the temp in workshop and it was Rising reletively fast, so I will disable Enable signal when motor is in standstill.

Normally I operate the motor on high speed so there is enough cooling.

Thanks again for your answer

 hi guys,

i have same issue with sinamic s120  cu310-2dp, p1300=20 sensorless vector,

when speed increase overspeed fault comes,

i use it on elevator ,

with low speed issue reduced , but speed is less than normal,

i did stationary autotune only, i think may be need activate autotune with motion sensorless ,

please advise for solution,

 Well your problem can be sorted out in one of these two possibilities:

1) Mechanic is not correctly dimensioned so your desired dynamic exceeds the motor/coupler maximum dynamic (intended as speed in this case). So check the speed of your drive and see if it exceeds the maximum speed that your drive/motor can handle. After that check also the torque required because it could be too much and your drive/motor cannot reach that high torque.

2) If point 1 has been controlled then it could be a problem of regulation, but in that case you need to check the speed error and see if it comes during the linear speed moment or during start/stop of the movement, and try to adjust the gainings to overcome this situation (an alternative way is to reduce brutally the ramps that you are using, in order to get a smoother movement which will reduce some troubles). This second point is of course lot and lot harder than point 1, and is pretty difficult to support you from a forum.