PM-1640TL VFD Options

[mksj]

The derating for a native 3 phase input VFD varies by manufacture and model, the 2X over sizing based on output amps under the rated conditions (variable torque, constant torque, ND, HD, other de-ratings) is a general rule. The Yaskawa drives it is 1.7X, and the addition of a DC buss choke reduces the current spikes to the capacitors that causes the increase THD when using single phase input. Yaskawa also indicates that a DC Buss choke is used in this application, but you will find that many if not most factory installed VFDs do not use them for these smaller drives. Since the manual lathe is almost never run at 100% load continuously, the actual amperage rating needed is less. So 14A x 1.7 = 23.8A for the GA50U2030ABA which should be fine. Nothing wrong with going with the GA50U2042ABA and/or not using a DC choke, but the input wiring and breaker rating typically would be larger/higher. I often end up using the 3 phase input VFD in a derated mode, I figure if one were to sell the machine at a later date it could be used with either 3 phase or single phase. A single phase input VFD only has a L1 and L2 inputs.

All the Yaskawa GA500/GA800/V1000 have a dc buss link should you chose to add a DC buss choke. The GA50UB018ABA is designed for single phase input, so a DC buss choke is not needed. A native single phase VFD is basically a larger 3 phase VFD running in a derated mode. The use of a DC choke does reduce the input fuse sizing for some VFDs, as well as the THD generated.

I have not seen an issue with VFD electrical interfernce issues with the higher end VFD's, with proper grounding and shielded cables. A DC choke and/or an input choke does decrease the line THD, I have only used a DC chokes in a few builds. In my own systems I do use an input EMI RFI mains filters but for no particular reason. I have yet to use a line reactor for the smaller VFD systems. Due to the size and cost of the line filters, nice if you have the room and want to spend the money, but not something I routinely use. If you do install one, then you want one specific for VFD use and the input current rating of the VFD.

Discussion on E-Stop function, I do not use typically use the STO in this application because it negates any VFD braking. The Yaskawa has a programable input for an E-Stop, which has a separate deacceleration rate as well as overiding any other run command and requiring all run commands to be removed before it will reset. If I were to use the STO, I probably would program the VFD output relay to engage at 0 speed and activate the STO. Haven't done this, since the intent is stop the machine as fast as possible and prevent accidental restart with release of the E-Stop. The latter is achieved by both programmed E-Stop input and the system control latching power relay which drops out in any fault mode. This can only be reset when the spindle switch is in the stop position, and also includes the foot brake application. An external braking resistor is required for fast stops and to prevnet buss over voltage errors. The Yaskawa also has different programable modes to prevent an over voltage error.

Wiring Vevor VFD Control Panel in Remote Location

I just purchased a Vevor VFD for my lathe. It is a model A2-8075 - 7.5kw 10HP. The literature says the Smart Digital Display (control panel with stop/start and other push buttons plus LED display) can be removed from the VFD enclosure and mounted remotely. I downloaded the installation manual...

www.hobby-machinist.com

GA50UB018ABA install on the 1440C single phase input (not my VFD install)

GA50U2056ABA install for a 10Hp motor, single phase or 3 phase input

 

[Oops!]

The derating for a native 3 phase input VFD varies by manufacture and model, the 2X over sizing based on output amps under the rated conditions (variable torque, constant torque, ND, HD, other de-ratings) is a general rule. The Yaskawa drives it is 1.7X,

In the interest of learning so I don't feel as though I'm wandering around in the dark the next time I want to size a VFD, where do you find the 1.7X figure for Yaskawa GA500's? I was able to find a "Single-Phase Input Derate" chart, table 6 for 240V single phase input three phase output in the "Yaskawa GA500 Selection Guide" (one page of which is attached below).

For the 2030, it shows "1.5" for the Motor Power (HP), and "6" for the Motor FLA. The 1.5 is eerily similar to the 1.7X you mentioned, and would make sense I think in the 5HP (HD) scenario as 7.5HP / 1.5 = 5HP so that seems to imply the 2030 would work for the 5HP drive in question. However, what does the "6" in the FLA column represent? If I take the HD FLA spec of the 2030 and divide it by 6 I get 25A / 6 = 4.1667A which is a far cry from the 14 FLA the motor wants. I'm obviously either in the wrong document, or completely misunderstanding what the table data represents. And I know I'm completely missing the boat when I try to understand why the figures change from 1.5 & 6 without a reactor to 3 & 9.6 with a reactor.

I'm hoping if I can learn how to deal with this 1-PH derating with Yaskawa it'll give me a good idea of what to look for in the event I'm pondering a different manufacturer next time, as well as remove the uncertainty of "Is that drive going to be big enough" in this instance of course. There's so much more in your last post to digest, but it trips my OCD circuit breaker when I can't figure out how to get the numbers to work out for step one

Derailed again at the starting line,
-Doug

 

[mksj]

The derating is a bit of a moving target and as usual you need to look up the specifications for the particular drive, model and if using a DC choke. The standard historically has been 1.73 and that is what I have been using for my Yaskawa installs, but seems that the newer models of almost all VFD's are wanting a higher derating number. In addition one is not running them at full output for any length of time. The latest Yaskawa single phase derating for the GA500, they are recommending the GA50U2042BA with a 32A DC choke for 15.2A output current. Seems a bit excessive, over-sizing but then it is what it is, so that or the single phase GA50UB018ABA which is a monster VFD. The Hitachi WJ200 drives use the 1.7 derating but there newer drives require a significantly higher derating. A significant factor also has to do with the overload setting one chooses (ND or HD, as well as the duty cycle). So you are not as derailed as you think.

 

[Oops!]

Seems a bit excessive, over-sizing but then it is what it is, so that or the single phase GA50UB018ABA which is a monster VFD

Yes it does seem a bit excessive, but I assume they know what they're talking about. The B018 wants 8 and 10 AWG wire for input and motor respectively, the 2042 wants 6 AWG for both unless I want to "cheat" because the motor shouldn't draw that much current which seems like a bad idea. I think for the definitive applicability the B018 is going to be my choice. Man, nothing is ever easy (NIEE)...

The next step (gee, I made it to step two, time to take a break!) is the braking resistor. The selection guide shows R7510, two of them, and they're 62 ohm 150 watt resistors. I can't find anything that talks about if you'd want to wire those two braking resistors in series or parallel. Is there a B018 specific manual or supplement somewhere I haven't found yet? Everything I've seen only refers to a single B1 and B2 terminal for the braking resistor, unless the B018 is special and has B1a B1b B2a and B2b terminals or some such.

As much dynamic braking as possible without bus faults (which stops all dynamic braking and can't be healthy for the drive) is important to me. The 10% duty cycle units (the R7510 is a 3% unit) suggest they'll do 150% braking torque where the 3% units say close to 100% torque, but those 10% units are separate cabinets and the one for the B018 is 12x12.5x10.5 - I don't think the braking is THAT important to me.

My understanding is that for dynamic braking, the motor is essentially turned into a generator and the drive needs to dump that extra power off using an internal transistor through the braking resistor(s). Less resistance meaning more or faster power draining makes me think the two resistors would be in parallel but that's just a WAG. Is it a thing to design a FrankenResistor that'll drain power like crazy, more so than the standard braking resistor(s), as long as it doesn't confound the internal transistor? The reason I'm wondering is I've seen the two-stage braking switch in one of the designs, and that seems exactly like something human error (an apt pseudonym for myself) would notice was in the incorrect position after the fact. So some extra capacity in the dynamic braking area to be able to skip the 2-stage switch while still getting decent deceleration times at all speeds and loads would be appealing. Alternatively this might be something that could be addressed with an FPGA or microcontroller to dynamically assert the two-stage signal to the VFD based on encoder feedback from the spindle for RPM, but that's a whole other set of projects. Thinking about your comments on the Safe Torque Off (STO) thing, I think when the time comes that I smash the big red button I want the spindle to stop as soon as possible regardless of where I had left the 2-stage braking switch. I haven't crashed a lot of manual lathes (yet), but I can't think of a scenario where reaching for the E-stop in a panic would be made better by some huge work piece in a giant chuck spinning down gradually.

And then there's the thing about shutting off power with a resistor fault. The tech ref says:

◆ Install a Braking Resistor: ERF-Type
Connect the braking resistor to drive models B001 to B018, 2001 to 2021, and 4001 to 4012 as shown in Figure 3.54.
When you use a braking resistor, set L8-01 = 1 [3% ERF DB Resistor Protection = Enabled] and set one of the MFDO parameters H2-01 to H2-03 = D [MFDO Function Selection = Braking Resistor Fault]. Use a sequence to turn OFF the power with a MFDO.

Which power are they referring to exactly? It's my understanding that a breaking resistor fault will cause the drive to cancel any dynamic braking and the motor will just free spin down in RPM then need something to happen to clear the fault before it would return to normal operation. I wasn't planning on using a contactor to control power to the drive, and I don't see any real advantage to unceremoniously disconnecting the power in such an internal over-voltage situation. What am I missing here? I'm hoping their general language is geared more towards some other more complex machine where it might make sense to stop everything else if the brakes just failed on one part of it.

Incidentally, my plan was to use a disconnect on the cabinet somewhere not too inconvenient, followed by a breaker since my garage (shop) outlets are 60A circuits so I think some more appropriately sized protection for the cabinet and power input cord would be appropriate, then an EMI filter and straight to the VFD. Maybe a torroid here or there as well, just for fun. So the VFD comes on and off with the disconnect, and the drive in combination with the controls provide the desired safety interlocks and such. That's not a bad idea, is it? Yaskawa really seems to want me to yank power to their drive with a contactor though...

Re-railed, possibly in the wrong direction,
-Doug

 

[mksj]

These are general suggestions on wiring as I am not an electrician. The wire gauge/type is specific to the panel breaker/fusing (with some exceptions), if you have a 60A circuit then the wire to VFD enclosure to the disconnect switch and fuse/breaker would need to be the same rating as the breaker, and after that you could go to #6 or 8 THHN depending on the fusing/breaker size in the VFD enclosure. The B018 recommends a 40A time delay (dual element) fusing (I use J class in this amperage), so you could use #8 THHN from the fuse holder to a noise filter (40A) and then to the VFD. The motor is only drawing 14A 3 phase, and the motor wiring is dictated by the motor amps, not the maximum output rating. So you could use either 14G or 12G, I tend to use the larger size wire. VFD input amperage/wiring is suppose to be a minimum of 125% of the input rating of the VFD, and is not dependent on the motor/load connected. When you get into a three phase VFD running in derated mode, I have not seen any information as to how this effects the input fusing, but in general I set these up the same as 3 phase, on single phase in derated mode you are using 2 fuses of the same rating as 3 phase. It does not change the output wiring to the motor.

The braking resistor is specified for the B018 is ~40 ohms, the duty cycle is very low as the braking time is 1-2 seconds in most cases so a 600-800W braking resistor is fine, with this little braking they never even get warm. A 39 ohm resistor is more commonly available and should be fine. Note the E-Stop programmed input has its own stopping rate, having two braking rates is handy so that something like threading it will stop quickly say 1 second, but genral use you might use 2 seconds.

https://www.mouser.com/ProductDetail/TE-Connectivity-Holsworthy/CJP800J39RJ?qs=vvQtp7zwQdP86MPqpJTuVA%3D%3D

You can set the VFD parameters so the you should not get an over-voltage buss error, basically the VFD will adjust the stopping rate so the bus voltage is not exceeded. With a braking resistor attached, then option 3 per the manual. I still check the lathe under different fast braking conditions as well as repeat fast braking and different weight chucks. There is a limit to the braking as the momentum increases.

 

[Oops!]

These are general suggestions on wiring as I am not an electrician.

Duly noted, I have a Sparky friend that blesses all of my wiring (er, up to the control panel anyway) so I'm covered on that part.

The braking resistor is specified for the B018 is ~40 ohms

The GA500 Selection Guide says for the B018 it's catalog code R7510 quantity 2, and the R7510 after you chase it down is 62 ohms 150 watts. Assuming the two are paralleled, that would give 31 ohms and 300 watts, no? There goes that OCD circuit breaker again with the numbers not matching up Where would I find that ~40 ohm figure, I feel like I'm missing a manual or something.

There is a 33 ohm 800W version on Mouser too, that might be what I'd go with.

You can set the VFD parameters so the you should not get an over-voltage buss error, basically the VFD will adjust the stopping rate so the bus voltage is not exceeded.

I was going to ask about that, it seems like a natural feature to adapt the braking to as much as possible without going over-voltage, so 3 it shall be for L3-04

The B018 recommends a 40A time delay (dual element) fusing (I use J class in this amperage)

Okay, again I feel like I'm looking in the wrong places, or misinterpreting the meaning of recommended and maximum. Here's the table from the GA500 Technical Reference manual.

It looks to me like they're recommending a 60A fuse in the Class J style. Or is that the max you can go, or by branch circuit they mean the wiring in the wall from the panel, or am I just looking in the wrong place entirely? The rated input current is 35A, and 125% of that is ~44A so that would drive the input wire size but it still leaves me fuzzy as to the source of the 40A fuse recommendation. 60A seems a little oversized to my well un-trained mind.

Also, your wire size table is different than what I have:

The header for the table I have in the Tech manual is

I'm beginning to feel like I'm a client of Confuse A Cat, Ltd.

 

[mksj]

Specifications are from Yaskawa documents for the GA500. "Recommended fuse" is from their technical manual. The fusing chart you indicated is the maximum size, not the recommended size. The main panel breaker meets the code if you did not have fusing in the enclosure, you can fuse in the VFD cabinet whatever you want as long as the wiring supports that fuse size (so 40, 45 or 50A J class dual element). Yaskawa GA500 Adds gives the information on the ancillary adds. Typically there is a range of braking resistance given, I have only seen the braking unit they use for the model. Typical braking resistor for this size VFD would be 25-50 ohms, they use 40 ohms, I choose 39 oms as that is a standard size. You can always contact Yaskawa technical if you want additional recommendations/specifications, that is what they there for.

 

[Oops!]

"Recommended fuse" is from their technical manual. The fusing chart you indicated is the maximum size, not the recommended size.

To clarify, what that chart is referring to as "branch circuit protection" is the 60A breaker in my electrical panel and the wire that will be run to the disconnect I install on the lathe, correct? So far, so good.

What I can't find is any reference to a 40A fuse on the input of the B018. I've searched all of the documents I have for combinations of "recommend" and "fuse" and I don't see a table for inside the cabinet drive input fusing. They mention MCCB's and contactors and EMI filters and reactors but nowhere do I find a recommendation for a specific input fuse size other than relates to the branch circuit. I know what the drive is rated for on the input side so it's not a problem picking a fuse size based on that, I'm just struggling a bit with all of the definitive directives in the documentation that are apparently routinely ignored in practice. Without years of experience it's difficult to know what you should trust and what can be safely disregarded.

For example the docs specifically say if you use a braking resistor you must add a contactor and remove power from the drive on a braking resistor fault, which I think is a bad idea and have seen numerous examples of not doing that and having very functional setups. Another part says all control wiring should be twisted pairs, and another says all control wiring should be shielded. I don't know why you'd use twisted pairs for single ended signaling, but I suppose you could run the common with each and every wire through every switch and relay keeping the shield contiguous and terminate it at the drive input terminals, but I've never seen that done. So from the perspective of someone like me wading through all of the docs trying to figure out how to get what's actually a fairly straightforward installation done "correctly" it's a nightmare of contradictions. My experience with tech support for these types of things as "a guy in his garage" is unless you get one of the stellar techs, and they are out there, you end up with the full CYA code infused liability waivering nuclear reactor safety requirement summary or in the worst case "Do what it says in the manuals". Which makes people like you invaluable by the way, so thank you so much for steering me through this maze.

Rant completed, here is my plan such as it is at this point. I've seen various discussions of which fuses should be used on drive input power in order to "better" protect the drive. To my simple mind, the drive is a pretty sophisticated piece of kit with all manner of protections built in to handle the motors and faults and so on. The only reason the drive should ever start drawing crazy amounts of power is because it's broken in some internal way. Once a drive is broken I'm not going to be tearing into it with a scope looking for the problem, nor am I going to box it up and ship to to Yaskawa or someone else for a lengthy and probably expensive repair process. I'm going to get a new drive, set it up, slap it in there and get back to it. Therefore I don't really see any reason to put wicked fast fusing in front of the drive to save it from being more dead than it already would be. My objective would be simply to prevent it from taking out anything else as it self-destructs. The power consumers are going to be the drive, the coolant pump, and possibly a 24VDC power supply if the control circuitry ends up getting close to the 150mA limit from the drive's internal 24VDC supply. It may just be common practice to always use an external supply anyway, and if at some point a tach or other additional control wizardry might be added I think it's probably best just to get a DC supply in there and not have to worry about it.

I'm thinking after the disconnect, three 2-pole 240VAC supplementary protectors (UL 1077 type) bussed together (Eaton style) protect individually the drive, the coolant pump and the DC supply and associated control circuitry. 40A for the drive, 0.5A for the coolant pump and 1A for the DC supply (so up to ~240W of 24VDC if needed). The drive will get an EMI filter as you previously identified, and the coolant pump and DC supply may or may not depending on how crowded things get and how noisy they may be, but the interior power should be nice and clean for whatever ends up going in there and everything else in the shop as well. I'll need to see how PM powers the DRO and account for that as well, I don't really want to have to run a neutral to get 120V although it is an option.

I realize that's not an industrial approach to these types of things, but for my stated objective of letting individual components destroy themselves if they must, without taking everything else and my garage with them in the process, is my approach reasonable?

I could go with UL 489 breakers, but I don't see a real advantage from a perspective of essentially limiting the destruction.

Thank you again for sharing all of your hard earned knowledge!

-Doug

 

[Beckerkumm]

Even though I restore my own machines, I just send Mark some money and let him do the electrical design and parts acquisition. Best use of my time and the result is way better than what I'd get on my own. Dave

 

[Oops!]

Even though I restore my own machines, I just send Mark some money and let him do the electrical design and parts acquisition. Best use of my time and the result is way better than what I'd get on my own. Dave

I thought real hard about that Dave, but in the end I enjoy learning about this kind of stuff and it's helpful if I've got a good understanding of things if I ever have to troubleshoot something. It's part of the hobby as far as I'm concerned and I'm glad I've got the time to spend on it as I creep up on retirement

Cheers,
-Doug