gear box change on Siemens Micromaster 420 controlled motor

[bdauliya]

Hello Everybody,


Recently we changed the gearbox which has different ratio than the original one on a motor which is controlled by Micromaster 420 vfd . Now I see the speed is not upto required speed.

Is there any way to make changes to parameter list on drive to match the speed as before with this new gearbox ?

Thanks in advance!

 

[Jim3846]

Yes, it would be the commanded speed
Not sure how your commanded speed is in either 3 places typical. Read manual!
it can be done by either hardwired input speed control.
Pot dial on front if in local control
If some type of networked speed control. Go to that word to change speed

Need a Tach to read the speed on your unit.
You can calculate the new speed by a cross multiple

old Hz new Hz
----- ----------- = -----------------------------------------
TachSpeed RPM Speed I need RPM

for some reason formatting above is sketchy

Cross multiply and divide above get your new Hz

 

[bdauliya]

Thank you. I will give it a try.

 

[parky]

It will depend on how you control the drive & the difference in the gearboxes, for example: let's assume the speed is normally controlled from either an analogue from the PLC or a potentiometer, then if the gear ratio is not that greater difference then just increase the max Hz on the VFD for example if it is say 50Hz then increase the range to perhaps 65Hz bear in mind that there is a limit that the motor will run at a higher frequency than it's rated.
I have seen drives perform well even at 80Hz, the analogue signal i.e. 0-10v will give out a frequency of 0-max of the settings so for example if the min speed is 0 & the max speed is 60Hz then the 0-10v will equate to 0-60Hz, by increasing the max Hz setting to say 70Hz will give a range of 0-70Hz on the 0-10v.