vfd question

[John RutzenParticipant @johnrutzen76569]

I've set up as you suggested Martin. It runs fine but of course the torque reduces severely as the speed drops. I find that trying to reduce speed below 50% and trying to drill a 1/4 inch hole the drive cuts out Err6 which is overload. I've got the current set at 2000mA. What do you think I could safely increase it to?

[Martin of WickParticipant @martinofwick]

A) In my limited experience of these simple devices, the display voltage and current is probably not a true indication of the actual RMS voltage and current taken by the motor. However, the indicated display is what the overload current setting will cut out at.

This makes setting a meaningful overload current cut out problematical. Ultimately it will depend on how bold you are or how much you think your motor will take. A reasonable quality induction motor is fairly tolerant, so here is what I would do as a start.

check current draw indicated at no load – say it was 2.0A the real current load should be closer to 1.1A divide 2/1.1=1.8 now say you will tolerate 1.5A for a short run overcurrent ( say 3 seconds set at parameter P24) then multiply that by 1.8 which will give you 2.7A as a possible overcurrent setting. If it was me, I would set it at 3, but be prepared to check the temperature rise in the motor if working it hard.

B) There is not enough information on how you have set up for your drilling operation. At half frequency, the power being delivered in your system is only about 110 watts. depending on how hard the steel is and how sharp your bit is and whether you are using the correct RPM, that may not be sufficient to maintain speed/Hz relationship so the VFD pulses open up delivering additional voltage and current until the trip is activated (or not, in which case the motor will potentially overheat if care is not taken).

In the first instance, leave the motor at the full frequency and set the pulley system to give somewhere in the region of 800 -1000 RPM for 1/4 in steel ( we are in the home workshop here, not industry). With a low power system, if you have to use the VFD to reduce spindle RPM by as much as 50%, to trim to an optimal setting then consider setting up with pulleys for a lower than optimum spindle speed, but use the full motor frequency (50 Hz). That way you will get the maximum power to the bit.

A VFD is not a substitute for the correct motor gearing.

I cant believe you are getting no torque at the 50% setting, but if you are, check that P02 is 110 and P03 is 25 with P04 P05 both zero.

Edited By Martin of Wick on 02/04/2020 21:39:19

Edited By Martin of Wick on 02/04/2020 22:07:15

[John RutzenParticipant @johnrutzen76569]

Thanks for your help Martin. I've got it running pretty well now. I've set the speed to 990 rpm on the pulleys and at that and with a 2A max I can drill 1/4 holes in steel no bother with the speed reduced to about 600 rpm. I've checked the actual current by changing P62 to read current and it's just about 1A while drilling so I don't know why it cut out before. I have been looking up other forums about using these motors at higher frequency and they suggest it's fine to run at up to twice speed for a 1400 rpm motor because the construction is the same as for a 2800 rpm motor. I can't however adjust the frequency above 60Hz for some reason even thought the manual says 0-400Hz. The motor is a Teco Westinghouse and the plate says it is also for 60 Hz.

[Martin of WickParticipant @martinofwick]

Uh-hu…

you can cycle between rpm/ amp/ volt/ hz/ hrsrun/ temp by pressing the function/data key P62 just sets what comes on the display at startup.

Check how you have set P06 that sets the max Hz I would recommend no more than about 75Hz – that is 50% inc on design freqency. While it may be OK to run the motor at 2500 RPM, the torque will not be as expected, approx 50% relative to the higher speed.

The overspeed will be fine if you are wanting a speed boost for using a very small drill or some other low torque operation. However, if say using a large forstner in wood, there would be insufficient torque to maintain the set speed, so you may not gain much in that case, or by going to much higher frequencies (unless you are regularly using sub mm drill bits).

Looks like your display current is more accurate than some, which is good. I could have suggested another way to set trip current for real world practicalities. Get a large chunk of gnarly steel about 2 in thick and your largest drill (I assume 1/2- use an old bit you don't care about) set machine gearing for approx. RPM for material and start drilling like you don't give a **** while observing the indicated current, then set that or just above that as your trip current – as being defined by the nastiest job you are likely to do!

 

Edited By Martin of Wick on 03/04/2020 11:45:16

Edited By Martin of Wick on 03/04/2020 11:48:40

[John RutzenParticipant @johnrutzen76569]

Hi thanks Martin, adjusting P06 did the trick. I only want the higher speeds for very small drills but it also means I can gear down further. I think now that about 2 to 1 is the useful speed range of these things. It's also taught me why my milling machine has a brushless dc motor rather than a 3 phase motor. The brushless dc motor still has bags torque at low speed, the belt slip is the limiting factor there. It's a pity it hasn't got a back gear but I can't see any way to fit one.

[John RutzenParticipant @johnrutzen76569]

Hi Martin,

I have ordered another vfd to put on my lathe which has a 3 phase motor. I would like to fit a remote push button switch. Please could you tell me whether these should be momentary push buttons or latching? There is nothing on the instructions to help and the Youtube videos aren't very clear on the matter. Thank you , John

[Martin of WickParticipant @martinofwick]

John,

you can use either momentary or latching, depending on what parameters you program to the multifunction inputs P50 to 55.

The supplied 'manual' lists the switching types available, but has been so badly translated that the terms are meaningless in English and utterly unsatisfactory. Originally I worked out what they might be from the supplied description, but then experimented to prove the hypothesis.

See thread titled AT1 inverter 3 wire control, I think the very last post in that thread has a detailed description and practical descriptive use of the listed parameter functions (as determined by me on the examples that I have worked with). If you cant find it, let me know and I will PM you a copy.

Should at least get you going but you can always run a test setup to experiment with the switchgear of your choice to find what works best for your application.

Remember, AT1 multifunction inputs are all LOVO stuff so you don't really need expensive 600v /20A switchgear or to shell out Farnell/RS etc. Reasonable quality stuff from the usual eastern sources will do.

[John RutzenParticipant @johnrutzen76569]

Thanks Martin, I much appreciate your help. I've read the other thread and think I can understand that OK. I haven't got the inverter yet but I can source the buttons and enclosure now.

[Andrew FirmanParticipant @andrewfirman12129]

There are some comprehensive YouTube videos recently made by routercnc regarding programming a XSY AT1, fitting out an electrical cabinet for it and a control panel.

The videos are long because they include the mechanical stripping and modification of a Warco drill press in a series of 6 videos. If you just want to view vfd and motor content you need to skip to about 15 minutes in video EP1 for overview, 18 minutes in EP2 for detailed info on XSY AT1 program parameters and most of EP3 for electrical cabinet and controls.

[Andrew FirmanParticipant @andrewfirman12129]

I have a couple of 2.2Kw XSY AT4 which allow one to power 380V 3 phase star wired motors using 220v single phase supply.

I've bench run a 1/2hp motor successfully using the key panel for control but have run into a problem when trying to control speed using a 10K pot. For some reason I'm only able to obtain exactly half the max hz set in the vfd that I was able to achieve with the keyboard. I'm hoping someone will be able to advise why this might be the case and how I can get the full hz range using the Pot.

Unlike the other ATs in the series the AT4

1: has no earth terminal . I was planning to earth the cooling fins but measured 85v ac between the fins and supply earth. Is this to be expected? Should I earth it?

2: has only 1 COM terminal on the control ports. The voltage between this COM and the 5v/10v terminal measures 5v Could this be causing the half max hz with the Pot?

I can post photos of the manual (seems to be the same as what has previously posted) and the terminals once I figured how to.

 

Edited By Andrew Firman on 22/05/2020 18:58:06

[John RutzenParticipant @johnrutzen76569]

Hi Martin,

I've got my new vfd from china, 2.2kw and set up and running. The only problem i have with it is that there is a high pitch whistle. This varies with the output frequency. At 25Hz it's hardly noticeable and at 65Hz it's hardly noticeable. It's worst around 50Hz which is annoying. Have you come across this and is there anything that can be done about it.? Thanks, John

[Andrew FirmanParticipant @andrewfirman12129]

You can try increasing P22. The higher it is the less audible the noise is. It’s worth noting that a higher carrier frequency can cause motor to heat up.

[John RutzenParticipant @johnrutzen76569]

Hi Andrew, I'll give P22 a try. I think it's set at 10. It's says the range in 1-10 [1-20 for high ver]. I don't know what the high version is, do you? I'll try tomorrow adjusting it by 1 or 2 and see if it makes a difference. I'm quite pleased with the current consumption. It's a big motor but the plate is missing so I don't know the HP. I'm guessing its about a 2 HP motor . The current off load is only 1.6A which increases to nearly 3 A when driving the lathe [ Harrison M250] .Apart from the whine the lathe runs much quieter than before with no humming noise at all.

[Andrew FirmanParticipant @andrewfirman12129]

Hi John,

I don’t know what the high ver is . On my 2.2kw AT4 I can adjust to greater than 10 but it is currently set at 10 which was the vfd supplied setting.

I can hear the high pitched noise ( although I don’t find it too annoying – perhaps my hearing has degenerated!).

I’m not an expert but from what I’ve read increasing the carrier freq just to test whether the high pitched sound disappears should not hurt the motor.. However to operate the motor at a high carrier freq for longer periods may be another matter.

[John RutzenParticipant @johnrutzen76569]

I've reduced the P22 to 8 and that makes the noise a bit less irritating, That's what my other vfd is set at and it makes no whine at all. That has a new motor however and only 1/3 HP. I read on another forum that it's the motor making the noise , the windings are vibrating at the carrier frequency and new motors are better. The motor on my lathe is at least 50 years old so it could well be the case.

[Andrew FirmanParticipant @andrewfirman12129]

John, just curious, is your 2.2kw vfd an AT1 or an AT4?

[John RutzenParticipant @johnrutzen76569]

It's an AT1, I'd never heard of an AT4 until you mentioned it.

[Author]

Posts