SINAMICS G120 CU250S-2 4-20 mA signal for control speed

Hi all

Recently I have a problem with the control speed of a pump, for that control I'm using a SINAMICS G120 CU250S-2,  with an 4-20mA analog input connected to AI0.

The issue is as follows:

When the pump starts for the first time the Hz corresponds to the mA, but after a while, the Hz decreases to the minimum speed value despite we increase the amount of mA to the VFD.

I hope you can give me some advices to get it run.

You can find my Project in the attachment.

Hello,

In your attached project if the reference value i.e. AI0 is 4-20 mA, please check p0756 value. In project it is 4 means - reference is Bipolar voltage input (-10 V ,,,, +10 V) it is wrong. Change P0756 value to 3 i.e. reference is unipolar current input (4 - 20 mA) Also check the setting of DIP switch for U/I input.

HTH.

PISCEAN 2010

Hello,

In your attached project if the reference value i.e. AI0 is 4-20 mA, please check p0756 value. In project it is 4 means - reference is Bipolar voltage input (-10 V ,,,, +10 V) it is wrong. Change P0756 value to 3 i.e. reference is unipolar current input (4 - 20 mA) Also check the setting of DIP switch for U/I input.

HTH.

 Hi. 

I've checked p0756 and the value is 3, about the DIP switches are on "I" input. And the pump still has the problem. What else I can do?

Thank you for your kindly Help!

Please check the values in r0752 & r0755> Those value must match with the analog reference values which are connected at AI0 i.e. 3 & 4. e.g. if 20 mA (measure & confirm it at input) is injected at AI0 then r0752 should display 20 & r0755 = 100%