Hello,

We currently have a Micromaster 440 running a 100 HP air blower for wastewater oxygenation. The 440 is controlled by a 4-20ma signal from a dissolved oxygen sensor with the min frequency set for 46hz and max frequency set for 60hz. The lower the oxygen level being reported by the sensor the higher the output frequency to the blower. We recently made a parameter change P0640 from 110% to 115% as per the rating of the motor and completed the end of quick commissioning P3900 set to 3 (Only motor calculation).

When we started the drive back up it would ramp up to 60hz then ramp down to 46hz then stay there. With the oxygen level being low it should be calling for the 60hz output to bring the levels back up.

I am wondering if some other parameters got changed during this process. I am not to familiar with the analog configuration and was wondering if anyone can please help me troubleshoot this problem. P1000 is set to 7

Thanks a lot,

Greg

Found the problem..... Faulty oxygen probe.............

Hello,

We would like to temporarily control our blower from the keypad instead of the 4-20ma signal applied to ADC2 Terminals 10 and 11. I changed P0700 from 2 to 1. We are able to start and stop the drive  from the keypad but are not able to adjust the speed using the arrows, the drive ramps up to 46hz and stays there. P1080 is set for 46hz. Are there any other parameters to change to accomplish this? It seems like the analog input might have to be disabled. Any help would be appreciated.

Thanks a lot,

Greg

To control from the keypad set P1000 to value 1.

Is the internal PI Controller being used for this control?

Good Morning tractor thanks for the reply. I set P0700 to 1 and P1000 to 1 and the drive still goes to 46hz. The 4-20ma analog signal is sourced from a HACH SC100 controller which is connected to a dissolved oxygen sensor.

tks  Greg

P1080 is the min frequency

P1082 is the maximum frequency

Check these for settings, as something is setting the frequency for you.

Be aware that by changing P700, some of your digital inputs and outputs will be reset to default, see the manual below.. page 75.

MICROMASTER 440 Parameter List 6SE6400-5BB00-0BP0

In it basic form the Micromaster, with p700 and p1000 as you have set it will give you start / stop and set point from the keypad, you are using a BOP (basic keypad)?

I have used the PI controller within the drive for this in the past, but had difficulty with the DO is it increases or decays, such that I found it difficult to impossible to control at the required set point. The motor would only run at either full speed or the minimum speed, due to the way the DO I’d dissolved.

Come back if I can help further.