SOURCING A VFD - WHERE DO YOU GO ?

[Susquatch]

I spoke at length to a tech at emotors direct about braking resisters, particularly external braking resisters. I got a quote for a VFD and resister but the reality in a smaller lathe they're not needed. The internal VFD circuit provides excellent breaking capacity without overload danger.

I talked to a fellow at emotors too. He didn't really seem to understand my questions. So I called Teco and talked to a fellow who totally understood my questions and totally answered them.

Most of the discussion was around how much the VFD measures current and back emf to understand what the motor is doing. It was a GREAT discussion and I really came away from it feeling empowered and comfy. I think most users think the VFD simply outputs a 3ph voltage the meets the criteria programmed into them. But depending on the programming mode (eg SLV), it does WAY more than that. The Tecos actually monitor current flow and back EMF on an instantaneous basis to know exactly where the motor is, how much slip is being experienced, and how much correction is required. In a way its better than a position sensor in the motor shaft. That's why Tecos SLV mode is so amazingly smooth and responsive. Understanding how it works just bowled me over.

We also talked at length about electrical noise on the supply lines as well as in the motor power lines.

Lastly we talked about braking. He started off with what you said about internal braking. However, when I asked about emergency stops for my lathe, he changed his mind and agreed an external resistor was better for that. That led to a discussion of what they offered and my nose got a little out of joint. I don't really want to buy a different VFD and learn all different settings. But I do want FAST E-Stops. The standard TECO doesn't have that.

 

[DavidR8]

I'd bet that a Teco that accepts a braking resistor would be programmed exactly the same as your current Teco.

 

[TorontoBuilder]

I'd bet that a Teco that accepts a braking resistor would be programmed exactly the same as your current Teco.

yes it would.

IIRC Sus' lathe would be a 2HP model, would use the A510-2002-C-UE, which is $660, and a megaresisters' DB-602657 NEMA 1 Housing, w/ thermal switch and a 1.02 kW, 19.5 Ohms resister for a cost of an additional $ 807.7

I need to see what a 3HP system will cost for my chipmaster... E-stop from 3000 rpm would benefit from external resister

 

[DavidR8]

yes it would.

IIRC Sus' lathe would be a 2HP model, would use the A510-2002-C-UE, which is $660, and a megaresisters' DB-602657 NEMA 1 Housing, w/ thermal switch and a 1.02 kW, 19.5 Ohms resister for a cost of an additional $ 807.7

I need to see what a 3HP system will cost for my chipmaster... E-stop from 3000 rpm would benefit from external resister

Won't be cheap I can guarantee that. Durapulse from Automation Direct are also recommended via a friend on Hobby Machinist.

 

[Darren]

My 10hp lathe has both a electro-mechanical brake and an external braking resistor. Its possible to have so much weight spinning that neither alone will work well. Together they are pretty good. Without the mechanical brake and external resistor, I'd get nuisance trips of the VFD when braking from higher speeds.

The manual for the drive will specify the wattage rating and resistance for the resistor. Coincidentally, a stove element from the dump often meets these requirements, at least for testing.

 

[Susquatch]

I'd bet that a Teco that accepts a braking resistor would be programmed exactly the same as your current Teco.

yes it would.

If they have one, I'd agree. But as I recall, they don't.

IIRC Sus' lathe would be a 2HP model, would use the A510-2002-C-UE, which is $660, and a megaresisters' DB-602657 NEMA 1 Housing, w/ thermal switch and a 1.02 kW, 19.5 Ohms resister for a cost of an additional $ 807.7

The motor is 2.6HP. So it needs a 3HP VFD. Unless I missed it, TECO doesn't make a 3 HP unit with external braking.

1.4k is a lotta money to get resistive braking......

 

[TorontoBuilder]

If they have one, I'd agree. But as I recall, they don't.



The motor is 2.6HP. So it needs a 3HP VFD. Unless I missed it, TECO doesn't make a 3 HP unit with external braking.

1.4k is a lotta money to get resistive braking......

The A510 series has a 3 HP model that comes with an internal braking transistor but that will also accept an external resistor for applications requiring greater braking torque.

This is the model I briefly considered for our old lathe. I'm glad I didn't go expensive considering we sold that lathe

 

[Susquatch]

The A510 series has a 3 HP model that comes with an internal braking transistor but that will also accept an external resistor for applications requiring greater braking torque.

This is the model I briefly considered for our old lathe. I'm glad I didn't go expensive considering we sold that lathe

Thank you! I'll take a look!

I have to remember to measure the current windup time and set the braking time the same so I don't overstress the gear train. Perhaps I'll do that electronically.

 

[Susquatch]

My 10hp lathe has both a electro-mechanical brake and an external braking resistor. Its possible to have so much weight spinning that neither alone will work well. Together they are pretty good. Without the mechanical brake and external resistor, I'd get nuisance trips of the VFD when braking from higher speeds.

Yes, that's part of my concern. As mentioned above in my reply to @TorontoBuilder, I think the gear train will only take so much stress. An instant stop is prolly not the greatest idea. But I know it can take the current starting windup load so I figure that's prolly a safe braking load too. Perhaps I should measure it with a heavy chuck load too.....

My lathe has no manual brake. I've never liked that but it is what it is. An e-brake is infinitely better than no brake.

Does your manual brake stop the spindle or the motor? Or something in between?

The manual for the drive will specify the wattage rating and resistance for the resistor. Coincidentally, a stove element from the dump often meets these requirements, at least for testing.

I use stove elements all the time for such things. You can also get ni-chrome wire for that purpose and cut to length for the resistance you need. The beauty of a stove element is that you know it has the wattage to live at its design current. I wouldn't be afraid to use one permanently. On the other hand, a purpose made power resistor would look great on the wall...... "No Touchy"!!!

 

[MrWhoopee]

I bought a motor from emotors and was pleased with their knowledge and selection, I suspect vfd from them would be similar.
I bought 3 vfds from Amazon, all because of the very low price. I have 2 of them in service and have the third as backup should one fail. They have worked perfectly for me so far. As you said I also think many (but not all) of the vfds on the jungle store are essentially the same from different sellers.

Here's the one I bought
2.2KW Drive Inverter AC220V Single Phase to 3 Phase Variable Frequency Drive Inverter High Wide Speed Regulating Range Speed Controller Inverter for 3 Phase Motor https://a.co/d/cmWkYq5

They have more than doubled in price in the three years since I bought mine, but I do remember back then prices were all over the place then also.

I just put the Vevor branded version of this one on my Harig 612 surface grinder. Paid US $70 off eBay. I like it very much. Getting ready to get one for my lathe.

 

[Susquatch]

I just put the Vevor branded version of this one on my Harig 612 surface grinder. Paid US $70 off eBay. I like it very much. Getting ready to get one for my lathe.

I'd recommend against that.....

A lathe isn't like a mill or a surface grinder. A cheap VFD on those is a safe bet.

But the startup load/current on a lathe is HUGE by comparison. They are not in the same league. A lathe has to spin up all the gearing, the shafts, and the spindle & chuck. The rotating mass is ginormous compared to a surface grinder or mill.

Just yesterday, I was doing power consumption measurements for my shop. I have an emporia power monitoring system in my breaker box (highly recommended). Just for Shits and giggles, I tested the power consumption on the lathe. It was big all on its own. Then I changed the time base so I could see the startup power usage - it was off the chart!

Your lathe needs a higher quality VFD.

 

[slow-poke]

I wonder what would happen insurance wise if one of these non CSA approved "Amazon special "VFD's caused a fire and or other damage. I'm actually surprised an electrician would actually hook one up knowing it's not approved for use here? Anyone from the insurance industry have insight?

 

[Susquatch]

Anyone from the insurance industry have insight?

One of my sons works in insurance. He says your best hope is a total burn down. Any evidence like a non-csa VFD would negate your insurance.

He also says that the best insurance of all is to never need it...... LOL!

 

[DPittman]

He also says that the best insurance of all is to never need it...... LOL!

And to never buy it, unless of course you're going to need it.

Insurance premiums kept rising on my last house that I held a policy on for 35 years and I finally pulled the plug and didn't insure it anymore for the last few years of ownership. It felt GREAT not to have insurance premiums.

However I recently "upgraded" houses and am now paying insurance premiums again. I hate it.

 

[Susquatch]

finally pulled the plug and didn't insure it anymore for the last few years of ownership.

Just thank your lucky stars you are in the Prairies. In Ontario, that little FU stunt would have net you brand new starting rates just like as if you had a huge payout on your history. I actually did that once. I could not believe the cost to renew. It was just like I had an arson history. I thrashed around like a baby. But in the end, I paid through both ends. NEVER EVER CANCEL BEFORE getting insurance elsewhere.

 

[Darren]

Very unlikely that a vfd would cause a fire. There should be a switch to cut power when not on use. And the vfd should be in an enclosure anyway.

 

[Susquatch]

Very unlikely that a vfd would cause a fire. There should be a switch to cut power when not on use. And the vfd should be in an enclosure anyway.

Absolutely agree Darren. But that would not stop an insurance investigator from blaming it if it wasn't UL approved.

I can see the report now......

Several non-UL approved devices found. Shop clearly operated outside of standards. Claim Denied.

I hate insurance companies and I don't trust them at all.

 

[Mcgyver]

Very unlikely that a vfd would cause a fire. There should be a switch to cut power when not on use. And the vfd should be in an enclosure anyway.

The thing the creeps me out is just them finding it, even if the breaker to it was off, might given insurance a reason to balk at a claim. Some call it insurance, I think of it as the despicable weenie industry (except for lil' Susquatch who I'm sure is of sterling character).

I think a society of people who think and do is great thing and should be encouraged. Its the culture that creates the pursuit of education, learning, entrepreneurs, accomplishment and fosters interests in technology. All things Canada needs more of. The insurance industry wants brain dead people who will sit on the couch all night watching TV, and they punish you for not being like that. Easy to hate the @#$(#@'s imo.

 

[slow-poke]

We went through a three year fiasco with an insurance company when a repeat drunk driver hit and destroyed a car while it was unoccupied and parked in a driveway. They offered 1/3 of the actual value, when we engaged the court system, they delayed, delayed, delayed all while serving us with countless threatening papers stating that we would have to pay all the legal fees for their defence etc. Days before the court date they folded and gave us more than 3x their best offer. This is common practice nowadays. Most people have no idea what there car is even worth. This is how they treat their ticket and claims free for 45 years customers. I miss MPIC.

 

[TorontoBuilder]

The thing the creeps me out is just them finding it, even if the breaker to it was off, might given insurance a reason to balk at a claim. Some call it insurance, I think of it as the despicable weenie industry (except for lil' Susquatch who I'm sure is of sterling character).

I think a society of people who think and do is great thing and should be encouraged. Its the culture that creates the pursuit of education, learning, entrepreneurs, accomplishment and fosters interests in technology. All things Canada needs more of. The insurance industry wants brain dead people who will sit on the couch all night watching TV, and they punish you for not being like that. Easy to hate the @#$(#@'s imo.

Insurers and retailers are people I'd just love to despise.

They view every customer as a crooked person who lives to find ways to defraud them. Every retailer thinks every customer comes into a store to steal. Every insurer thinks every customer signs up for a policy in order to defraud them. I used to hang with a group of friends who all worked in insurance, on the claims side. They spent every day catching actual insurance fraud and it created that personal bias.

So who is worse, the people with the bias, or the society that created it?

That's a trick question, because in reality even without the bias it is legal in the insurance industry to use the presence of non compliant product not related to an incident to deny a claim entirely. That my friends is the result of lawyers and lobbyists, something only the industry has. You dont see insurance fraudsters lobbying doug ford.

I posit that there is no god, because a god could not create such a effed up system