Recent content by fab1961

I have to apologize actually the motor is single phase... I am an electronic engineer and sometimes don't use proper terms. Once again this forum has been very useful to me and let me say thank you to everybody.

Dear all, I need to run a small (less than 1 kW) two-phase motor (which in turn drives a cooling pump) for a shop test. Motor and pump are designed for a 60 Hz supply, while in our factory we have 50 Hz. My idea is to drive the motor with a VFD whose output frequency is programmed 60 Hz. Point...

Thank you to everybody for the good advice

Dear all, we are engineering a machine for a (potential) Customer in Washington state (Pierce county). We are supposing that the power supply is 480V Y 4-wire. Is there a way to doublecheck ? Thank you

Sorry gentlemen I was in a hurry and forgot to type that we double VDF size when the correct size is not available, normally we use same size as the motor. Or we pickup the next size available. As you pointed out there is current enough.

Thank you, actually we are using simple V/f on this application.

Dear all, as a rule of thumb we have always kept the VFD size (in kW) two times the motor size. Now we have a project where a 0.37 kW three-phase motor is to be driven by a 1.5 kW VFD - this is because of delivery times, we can't have a 0.55 kW in time for the job. Any suggestions? Do we have...

Thank you. What worried me most is some potential issues during working, when motors run.

Dear all, given a VFD sized for 4 kW motors is there any problem driving two motors 0.75 kW in parallel? In other words, how much smaller can be the load compared to the VFD? The driving mode is a simple V/f. Thank you

Good morning everybody, I would like to understand better (from the theorical point of view) what is the physics of braking with DC. Can you suggest me something to read? Thank you

LionelHutz, Waross, thank you for advice. What I was thinking of is using "normal" VFDs and wiring the DC bus using the available terminal blocks. I can confirm that a failure on one drive burns the other ones connected, it happened to us a couple of times using servodrives. In our applications...

Dear all, while with drives applications with permanent magnet motors it is a common practice to share the DCbus between drives, I've never come across a similar connection with VFDs (I refer to manuals, case histories etc. - we have been using in time Japanese and European VFDs of different...

Consider running the motor instead of braking it. When above base frequency (50 Hz Europe 60 Hz USA) the torque is reduced, we enter the constant-power area. If torque were not reduced, then, since power = torquexspeed, we would have infinite power since both speed and torque increase. Also you...

Dear all, in our applications we use braking resistors connected to VFDs. For a new plant I have to check more precisely how much braking torque is available. I consider the braking torque as [ ( V DCbus / resistor ) / rated motor current ] * motor torque at rated current * K where K is the...

Thank you everybody for advice - I owe you some more details: I wrote MCC to cut a long story short,in fact we are an European company and it happens to us to make electric panels not only for our machines but also for machines we purchase to deliver turn-key solutions - in this case the load...