[peteeng]

Hi All - So now I have an understanding of the wire sizes and types. Thks for all input. I shall wait until the spindle arrives to determine its plug size. The parts are now in the state so they are close... Peter

[mactec54]

Hi All - So now I have an understanding of the wire sizes and types. Thks for all input. I shall wait until the spindle arrives to determine its plug size. The parts are now in the state so they are close... Peter

You will want a 20A supply to support the 1.5Kw spindle comes with a spindle plug, you do not Plug a VFD Drive in it must be Hard Wired in your system and have a disconnect VFD Drive will have its own Breaker and EMI Power Filter at the input Power side to the VFD Drive

[peteeng]

Hi Mactec - I know you cover this in other threads so I'll look there. But is the power factor that bad on a VFD? 20Ax230V= 4600W or is this for the inrush? Peter

[joeavaerage]

Hi,
the power factor of VFDs is very poor, for those manufacturers who publish it, it ranges from about 0.5 to 0.6.

The issue is that VFDs draw current very unevenly rather than a sinusoidal current waveform, also called harmonic distortion. For the small VFDs
we use having such a low power factor is not a big issue, sure we're paying for 20A but only 'getting' 11A, not to mention that we need bigger cables and breakers etc.
In a big industrial VFD/motor combinations it becomes expensive and so correction techniques have to be applied.

The attached pic is the formula for the Distortion Power Factor (DPF) for a given Total Harmonic Distortion (THD). Schenider are one of the few companies that
publish all the details about THD and power factor for their devices.

The simplest of the correction techniques is a line reactor, basically three coils (three phase assumed) of about 5mH to 10mH. That would take a power factor
of 0.55 to about 0.8 to 0.85, quite a gain.

The next step up is active power factor correction. You might be surprised to know that there are many hundreds of millions of the circuits in existance, one in every PC to start
with. Quite some years ago the US realised that the PC power supply, being a line connected rectifier and capacitor, would introduce unacceptable harmonic distortion on
the AC network, and so regulated that power factor correction be employed, and that has been in place for decades now.

The idea is quite simple, that the power supply be preceeded by a boost converter modulated in such a way that the current draw is quasi-sinusoidal. The IC to do so can be had for
under $1.00 each.

Large power factor correction circuits use the same idea but have to handle many tens or hundreds of amps and cost a bomb.

Here in New Zealand we have seen a dramatic increase in the use of VFD controlled 'down bore pumps' for irrigation. These pumps range up to 500kW.
A VFD for such a pump might cost $50,000, but then you have to add another $25,000 for the power factor correction unit. Not surprisingly the farmers object,
but unless they mitigate the current distortion the power supply companies will refuse them service. The existing installed base of VFDs prior to this restriction becoming
universal is such that in rural areas in New Zealand PCs, TVs etc tend not to last long before they get fried by all the harmonic currents.

As I posted earlier I don't have a screened VFD/spindle cable, but that has not been a problem. What I found though was that when I put a line reactor preceeding the VFD
I reduced a lot of noise effects in my control circuits. I concluded that the harmonic currents of the VFD were leaking through the power supplies of my PC and other electronics
and that a line reactor all but stopped those harmonic currents, and naturally improving the power factor.

Craig

[peteeng]

Hi Craig - so what line reactor did you use? so I can find one in Oz?

https://www.motioncontroltips.com/fa...-line-reactor/

something like this?

https://au.rs-online.com/web/p/sine-...B&gclsrc=aw.ds

Ta Peter

[joeavaerage]

Hi Peter,
yes those are the sort of thing. Note that almost all of them are three phase and consequently tend to be expensive.
If you connect the coils in series then you can increase the inductance. Lets say you want an overall inductance of 6mH, then if your three phase reactor has three 2mH windings
you'd connect them in series. There is a trap however, you must connect them in phase with each other or you'll fin that by transformer action two coils will cancel each other out.

Some of the cheaper three phase reactors have limited current, say 3A. If you connect them in parallel you increase the current capability to 9A, but reduce the inductance to
one third of any one coil. There again you have to pay attention to phasing or it wont work.

I made my own single phase reactor from an old transformer. I've been recycling transformer cores since University days.

Craig

[mactec54]

Hi Mactec - I know you cover this in other threads so I'll look there. But is the power factor that bad on a VFD? 20Ax230V= 4600W or is this for the inrush? Peter

The problem you are looking at is your spindle is 3Phase and your supply is Single Phase, so on an average the input current needs to be roughly double the output, 1.732 x 6.5A=11.3 amps minimum round this to 12A without the rest of your machine, you only want to be using (1) 230v supply to the machine so a 20A supply will bring you into the ballpark of what you want to have for your complete machine

For what you are getting the VFD Drive is very efficient

If you had a 3Ph supply, then you would not have / need this extra required input current

[mactec54]

Hi Craig - so what line reactor did you use? so I can find one in Oz?

https://www.motioncontroltips.com/fa...-line-reactor/

something like this?

https://au.rs-online.com/web/p/sine-...B&gclsrc=aw.ds

Ta Peter

You don't need a line reactor for your install.

It's good to have an EMI Power Filter though

[mactec54]

Hi Craig - so what line reactor did you use? so I can find one in Oz?

https://www.motioncontroltips.com/fa...-line-reactor/

something like this?

https://au.rs-online.com/web/p/sine-...B&gclsrc=aw.ds

Ta Peter

The use of a VFD Drive actuarily can help with PF correction, because it uses IGBT switching which most VFD Drives use, years ago they used Diodes switching and this was not very efficient and required you to use a Line Reactor

It's the induction motor you are driving is what has the PF problem not so much the VFD Drive, the VFD Drive has Harmonics that do cause a disruption which can be taken care of with the EMI Power Filter, most quality VFD Drives have EMI Filters built in so very little Mains Power filtering is required to become EMC compliant

Here is an article on how the use of a VFD Drive corrects the PF, there is lots of information like this if you search for it
How VFD improve the system power factor? | GoHz.com

[joeavaerage]

Hi,

f you had a 3Ph supply, then you would not have / need this extra required input current

BS, the current draw of a three phase VFD is just as distorted as a single phase VFD delivering 1/3 the output. The degradation of power factor comes about
because of harmonic distortion not inefficientency.

the VFD Drive has Harmonics that do cause a disruption which can be taken care of with the EMI Power Filter,

More BS, an EMI filter is to reduce Electromagnetic Interference, in particular radiated Electromagnetic interference. If a device cannot meet the FCC
requirements it cant be sold in the US, and as a consequence all the manufacturers ensure their devices do comply. That does not prevent current waveform distortion
and consequent poor power factor. EMI filters have some series inductance typically 50uH to 100uH whereas for your setup you want 5mH, an order of magnitude higher.

The standard reading for this is :

IEEE 519-1992
“IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems”. This is the most
widely accepted recommendations for harmonic currents and voltages

The regulatory codification is:

The harmonic current produced by switched-mode power supplies (Figure 1) can severely compromise the voltage quality of mains, and the international standard IEC 61000-3-2/
EN 61000-3-2 exists to set limits on the amount of harmonic current that equipment may output.

The codes in New Zealand and Australia are:

Electricity Distribution Code, Essential Services Commission, Victoria, Australia
The Essential Services Commission is the independent regulator of the energy industry in Victoria, Australia.

New Zealand Electrical Code of Practice for Harmonic Levels, NZECP36: 1993
This code of practice is prepared by the Ministry of Commerce and is pursuant to the Limitations of Harmonics Levels
Notice 198

Here is an article on how the use of a VFD Drive corrects the PF, there is lots of information like this if you search for it

This is correct, a particular use of a VFD. The same thing can be done with a synchronous motor/generator with a high field current, it has a leading power factor and can therefore be applied
in a network with a typically lagging power factor to advantage. In the Islington Station, not too far from here there are three 8MW synchronous motors used for exactly this purpose.
I hate to think how much those motors cost but when applied properly they actually save the power company money.

The bottom line is that most low output VFDs , say less than 5kW, do not require a line reactor. The saving in electricity costs is minimal and is mostly disregarded.
The times where a line reactor has a distinct benefit is is your power supply is on the weak side. Such a supply will have voltage disturbances because of the VFD
current and those voltage disturbances can be conducted into PCs/CNC electronics. A line reactor will cause the VFD to draw less current, by as much as a third,
and that weak power supply may well work whereas without a line reactor it would fault out. Another time where a line reactor is beneficial is if you are trying to power
a nominally three phase VFD with single phase. It does work but gives the input section of the VFD a hard time and must be derated. A good line reactor will help that alot.

In addition to the line reactor I also use two stage EMI filters at both the VFD input and the PC/CNC electronics input, at $40 each why wouldn't you?.

Craig

[Buoyen]

The thing is most hobbyists dont do 1.5kW cuts with their 1,5kw 24k spindle.

You need the power capability (current capability) so you have enough torque at lower rpms. But with smaller cutters/higer rpm cut the power of the cut is still low because the needed torque is lower.

That's why many drive a 1,5kW/2,2kW spindle on a regular 1ph 16A with great success.

I am not sure the cheap 1,5kW spindles would hold up long if you actually programmed a 1,5kW cut?

[mactec54]

Hi, BS, the current draw of a three phase VFD is just as distorted as a single phase VFD delivering 1/3 the output. The degradation of power factor comes about
because of harmonic distortion not inefficientency. Craig

No Bs just the basics, it would help if you had an understanding and education of electrical systems, instead of pretending you know something, what I posted was nothing to do with Harmonics, but current draw for Single Phase and 3 Phase (wedge)

A line reactor works best for low frequency use 50Hz / 60Hz when you use these high frequency spindles 400Hz and above the line reactor can be a problem, your lack of any real-world experience which shows every time you post

[joeavaerage]

Hi,

A line reactor works best for low frequency use 50Hz / 60Hz when you use these high frequency spindles 400Hz and above the line reactor can be a problem

Yes, that's right, the line reactor I'm talking about IS on the 50/60Hz side, thats why its called a 'line' reactor, and its purpose is to reduce the harmonic current distortion and thereby improve power factor.

There is also a load side reactor but the manufacturers seem only to recommend load side reactors with long cable lengths between VFD and motor.

Craig

[joeavaerage]

Hi,
this is a Yaskawa Application Note.

Craig

[joeavaerage]

Hi,
this is another Yaskawa article. Note on the last page the excerpt I have taken. Namely that at close to full output power the power factor of a VFD is quite high, say 0.89
whereas at low output, something like 1/4-1/3 motor current the power factor is low, 0.5.

If you have reason to increase the power factor, say a marginal AC supply, or a regulatory requirement, or a local induced noise problem the either a line reactor OR
a DC choke is a viable means of doing so.

Craig

[peteeng]

Hi All - My VFD adventure has begun. It arrived today with no manual. I did a search for a manual JR100-1.5kW-220V output 7A 2.8kVA with no luck. Have emailed supplier requesting manual. The issue is the input terminals are not marked. The outside sticker shows that terminal 6 is the ground yet there is a moulded ground symbol on terminal 8 & 1. So I wait for news from BST. Peter

[joeavaerage]

Hi,
seems plain enough, the sticker on the outside indicates what the screw terminals are, the leftmost two being 230VAC in, the rightmost two are for an external braking
resistor if you have one, the three motor phases and the earth are the remaining four.

What brand is this thing?

Craig

[peteeng]

Hi Craig - outside markings plain enough but inside no. No "brand" marking called "frequency converter". Will wait for manual before attempting anything. Peter

https://www.aliexpress.com/i/1005001266849915.html
this one but not from this store.

[joeavaerage]

Hi,
that's common for cheap Chinese VFDs, either no or poor documentation, I hope the price differential is enough to make the lack of
documentation worthwhile.


On Monday I took delivery of a 3.7kW Delta VFD for $958NZD, which includes GST and shipping. It came from the UK and it took nine days to get here.
The Element14 list a 1.5kW Delta VFD with single phase input for $794.60NZD which includes local GST and shipping.

https://nz.element14.com/delta-elect...motor%20drives

I could probably get it cheaper out of China but with shipping constraints the extra I pay to Element14 seems worth it to me.

Craig

[peteeng]

Hi Craig - $190USD for ER16 1.5kW spindle, water pump, hose and fittings. 1mm to 10mm collet set (12pieces including 1/8 and 1/4"), 80mm clamp and bolts plus said VFD. Not bad once I get it running. Currently all smoke intact. Peter