Huanyang VFD current draw measurements.

[EddyCurrent]

I think the current reading that's most relevant is the actual current draw at the entry point to the VFD

relevant to what ?

Regarding current, read this; http://www.industrial-electronics.co...ves-FAQ-2.html

[Edward]

Thank you, that kind of throws light on the difference between the panel reading and input current reading.

Edward

[Clive S]

relevant to what ?

Regarding current, read this; http://www.industrial-electronics.co...ves-FAQ-2.html

Hi Eddy I was waiting for you to chime in, Good read.

[Edward]

Relevant to what, you asked?

Well, for instance, the current at the input is relevant to me as I want to have some idea of how much current the whole system is likely to draw in total when at full blast, including 3 servos, air compressor, water pump and other minor peripherals. I have two mains rings in my workshop, so I may use the second ring for the compressor, which I haven't bought yet, but it will be the largest - silent type- I can safely get away with.

Edward

[magicniner]

Well, for instance, the current at the input is relevant to me as I want to have some idea of how much current the whole system is likely to draw in total when at full blast

Motor Stall Current multiplied by one over the VFD efficiency or the maximum rated current draw for the VFD will give you a far better idea of the maximum current under heavy working conditions than spinning up the motor and sticking a meter on the mains input.
Maths and manufacturers data are your friends here, not a meter and a finger in the air ;-)

- Nick

[Edward]

If you took manufacturer's info from certain devices, my Chinese servo for instance, you wouldn't even want to plug it in your 13A fused socket:) Steppers are another example. While some people spend their precious time solving complicated equations to do with inductance, back EFM and speed graphs, all I need to know - not being of a brainy disposition - is, can I plug it in with a reasonable margin of safety?

BTW, do you happen to know the Motor stall current x 1/VFD efficiency of the typical Huanyang/2.2Kw combo? I just can't find it anywhere in the instructions:)

Edward

[magicniner]

BTW, do you happen to know the Motor stall current x 1/VFD efficiency of the typical Huanyang/2.2Kw combo? I just can't find it anywhere in the instructions:)

Motor stall current should be on the manufacturer's spec sheet for the motor, VFD efficiency should be on the manufacturer's spec sheet for the VFD but you do to some extent get what you pay for.

If these are not available then ball park figures can be used from a device of similar specification from a manufacturer that does publish technical data and you'll still be closer to the number you are trying to get than you would be with a clamp meter, spindle running with no/moderate load.

- Nick

[Edward]

Hmmm, unfortunately there are too many variants that affect the actual current draw of a particular device, for instance the forces applied at the cutting end. And often practical experience will tell you more than a myriad of calculations.

And when I do some heavy cutting, I will observe the current to see where I am in relation to the max current set for the device, it will be interesting to know, that's all.

I only measured the input current with no load just out of sheer curiosity, nothing else, I am not trying to defy science;)

Edward