# VFD Size for single phase input



## glen1971 (Oct 10, 2012)

Every time I've ever sized a VFD with a single phase input it has always been at least 50% larger than the motor size. Today I ran into a Powerflex 525 that the smoke got let out of it, and I'm wondering on the sizing. The one that is showing the black screen of death is a 25B-4P8N104, which is 240 vac, single phase input and rated for 1 hp. The motor it is driving is a 3/4 hp, 240 volt 3 phase.
Shouldn't this drive be the next size up, to a 2 hp, or has ALB factored that in already? In the technical specs, under input phases, it says "Three phase input provides full rating. Single phase input provides 35% rating on three phase drives.".


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## MotoGP1199 (Aug 11, 2014)

If drive is specifically listed for single phase input on a 1 hp 3 phase motor at 4.8A. As long as the motor is 1hp or less and 4.8 amp or less you are fine. If it was a 3 phase drive and you are using it for a single phase input than you need to up size.

It is common for a lot of companies to make/sell a small drive(usually 3hp or smaller) that is pre set up for single phase input/3 phase out put. They already sized it and set it up for 1 phase input. No math needed on your part.


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## glen1971 (Oct 10, 2012)

MotoGP1199 said:


> If drive is specifically listed for single phase input on a 1 hp 3 phase motor at 4.8A. As long as the motor is 1hp or less and 4.8 amp or less you are fine. If it was a 3 phase drive and you are using it for a single phase input than you need to up size.
> 
> It is common for a lot of companies to make/sell a small drive(usually 3hp or smaller) that is pre set up for single phase input/3 phase out put. They already sized it and set it up for 1 phase input. No math needed on your part.


Perfect thanks! I had double check it, as I haven't seen one like this before. They are so super awesome to try and stab a meter lead in the back to check for voltage. Smh..


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## SWDweller (Dec 9, 2020)

You have checked all your Cat V meter equipment for breaks or cuts, right?


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## glen1971 (Oct 10, 2012)

SWDweller said:


> You have checked all your Cat V meter equipment for breaks or cuts, right?


Yup.. Meter is in good shape.


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## glen1971 (Oct 10, 2012)

Minor update.. They sourced a new 525 and a replacement is 30+ weeks out. They are looking at different drive manufacturers for a quicker delivery. I emailed the engineer and told him to pump the brakes on converting any other pumps over to this style of control, as the down time is totally unacceptable and not cost effective. Currently the pumps are on an ALB 609 manual motor starter, with manual rate adjustment, with no major issues. Someone has a cost savings idea to add a flow meter, a VFD and PLC control.


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## gpop (May 14, 2018)

glen1971 said:


> Minor update.. They sourced a new 525 and a replacement is 30+ weeks out. They are looking at different drive manufacturers for a quicker delivery. I emailed the engineer and told him to pump the brakes on converting any other pumps over to this style of control, as the down time is totally unacceptable and not cost effective. Currently the pumps are on an ALB 609 manual motor starter, with manual rate adjustment, with no major issues. Someone has a cost savings idea to add a flow meter, a VFD and PLC control.



Had a 525 to replace last month and ended up using amazon due to the same lead time.


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## paulengr (Oct 8, 2017)

glen1971 said:


> Minor update.. They sourced a new 525 and a replacement is 30+ weeks out. They are looking at different drive manufacturers for a quicker delivery. I emailed the engineer and told him to pump the brakes on converting any other pumps over to this style of control, as the down time is totally unacceptable and not cost effective. Currently the pumps are on an ALB 609 manual motor starter, with manual rate adjustment, with no major issues. Someone has a cost savings idea to add a flow meter, a VFD and PLC control.


On a pump application there is one and only one reason to use an AB drive. That’s only if you use the networking capability for communication and control. But for a pump application typically you need a run command, speed reference, and for feedback running and faulted status relays, and possibly speed and/or current analog feedback.

Long term Rockwell WILL change the network interface. They WILL change the addresses of the parameters. They have done this already at least once every 10-20 years. EVERY manufacturer has and always will. But other than switching from 120 V inputs in the 1336 VFDs to 24 V (in the 1990s), the discrete interface has not changed in 35 years. It is also the same with ANY other VFD manufacturer. We routinely change our VFDs for whatever make/model the customer wants.

We are somewhat independent. We distribute VFDs mostly from 3 different manufacturers. One has obscene lead times like you are describing. One can be hit or miss. The third has 50+ of what you are asking for on the shelf right now. Due to problems with the LA port they are air lifting VFDs until the end of the year, then rerouting to another port after that. I haven’t heard anything from the other two but we rotated stocking distributors with one of them as a result. By the first of the month we will be stocking essentially 3 each per “frame size” ourselves going forward because we are sick of it, too.

In the mean time we have a few sizes up to 75 HP as emergency spares. Most of it is old stock or “used”. It all works but it’s kind of hit or miss. We heavily discount that stuff because it’s obviously not new. We use them sometimes ourselves for shop motor testing.

There is nothing wrong with VFDs except this. I’m just going to say AC VFDs have been effectively under continuous development for about a century. There has been a major innovation about every 10 years. This has caused the chip suppliers and the drive manufacturers to design and build for technological obsolescence…every drive is built with a 100k hour (10.8 year) design life. And you can be assured that it is doubtful you can buy a 525 10 years from now.

So what you CAN do is plan and build your equipment to be brand generic. Use ONLY discrete signals (24 VDC inputs, dry contact outputs, 4-20 mA or 0-10 V analogs). Don’t use any special features. For instance Schneider has built in multiple pump control. Do that externally. If you do this a VFD change out even brand to brand is a 4 hour job. And you can buy from anyone.

Keep in mind two there are just 3-4 power transistor manufacturers. The drive you are buying has 12 diodes and 6 MOSFETs integrated into a single brick-like device called an IPM. The capacitor, control board, and a few other parts are strapped on top if it. There are really only 3 actual microdrive manufacturers. There is nothing special about a VFD that is private labeled from another manufacturer. All you are doing is paying triple the going rate for that Rockwell sticker. So there’s no way to tell AB from anyone else because chances are you are comparing the exact same drive or at least the same IPM with itself. I’ll even give you a hint: TMEIC. Do a little research on that company. It’s one of the biggest VFD companies that almost nobody has ever heard of.


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## glen1971 (Oct 10, 2012)

@paulengr, we had 6 VFDs on a data highway and we tore that out this spring. Everything is now a PLC output for run, a discrete input for status, sometimes one for a failt, 4-20 speed control and a couple with 4-20 feedback. They're all very simple control overall. 
I think AB is the drive of choice as 98% are 700s, a few 1336s, some newer 753s, two 1557s and a couple of 7000s. The are a few others that are a "one of".


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## paulengr (Oct 8, 2017)

glen1971 said:


> @paulengr, we had 6 VFDs on a data highway and we tore that out this spring. Everything is now a PLC output for run, a discrete input for status, sometimes one for a failt, 4-20 speed control and a couple with 4-20 feedback. They're all very simple control overall.
> I think AB is the drive of choice as 98% are 700s, a few 1336s, some newer 753s, two 1557s and a couple of 7000s. The are a few others that are a "one of".


Good so you learned to avoid that trap.

When it comes to drives plants tend to get hung up on brand names. It’s understandable. The menus and interfaces on some of them are terrible. The problem with getting hung up on brands though is that every so often the flagship model turns out to be garbage or there are support or supply issues. When that happens you need to be able to pivot.

So in this case you have a supplier charging 300% of market prices for drives, that charges for tech support, and that makes a noisy drive with very poor output filtering prone to causing massive bearing fluting issues. And they are now quoting crazy insane delivery times. I’d start seriously looking for alternatives. In fact we have all but dropped one vendor for that exact reason. And no it’s not AB…we aren’t distributors for them.


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## JRaef (Mar 23, 2009)

MotoGP1199 said:


> If drive is specifically listed for single phase input on a 1 hp 3 phase motor at 4.8A. As long as the motor is 1hp or less and 4.8 amp or less you are fine. If it was a 3 phase drive and you are using it for a single phase input then you need to up size.
> 
> It is common for a lot of companies to make/sell a small drive(usually 3hp or smaller) that is pre set up for single phase input/3 phase out put. They already sized it and set it up for 1 phase input. No math needed on your part.


Most drive manufacturers that offer a single phase input version do this, up to and including 3HP (2.2kW) at 230V. That's because the parts inside are too cheap to bother changing so they just use diodes (inside of the power module) and capacitors capable of single phase input. If you were to price them out compared to the 3 phase input version, you will see they are (usually) the same. This issue goes all the way back to the early 90s when inexpensive Asian PWM drives started hitting the market. For a while, some brands didn’t even bother offering a 3 phase version at 3HP and under (230V).


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## just the cowboy (Sep 4, 2013)

glen1971 said:


> @paulengr, we had 6 VFDs on a data highway and we tore that out this spring. Everything is now a PLC output for run, a discrete input for status, sometimes one for a failt, 4-20 speed control and a couple with 4-20 feedback. They're all very simple control overall.
> I think AB is the drive of choice as 98% are 700s, a few 1336s, some newer 753s, two 1557s and a couple of 7000s. The are a few others that are a "one of".


We had our " going forward plan" to use Ethernet to control our drives. We just went back to hardwired after blowing some pipe out of the ground because the Drive started when the PLC shut down, this was due to the drive program not having handshaking faults built in. 
We will just use e-net for misc. fault information.

Cowboy


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## JRaef (Mar 23, 2009)

As to design life, the PowerFlex 4 and 40 were just announced as becoming “End of Life” status next year. But that line of drives was released in 2002, making it 20 years old, not 10.8 years. You will still be able to buy them until the component parts that they pre-ordered run out, but many of the components are in fact no longer made. That is the truth about electronics, ALL electronics. The same thing happened to the old 1336 drives. Parts to repair them are even unobtainium now, forcing people to scavenge old drives for parts. Yet despite the product being introduced in 1991, making some of them over 30 years old, there are THOUSANDS of them still in service around the world.


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## paulengr (Oct 8, 2017)

JRaef said:


> As to design life, the PowerFlex 4 and 40 were just announced as becoming “End of Life” status next year. But that line of drives was released in 2002, making it 20 years old, not 10.8 years. You will still be able to buy them until the component parts that they pre-ordered run out, but many of the components are in fact no longer made. That is the truth about electronics, ALL electronics. The same thing happened to the old 1336 drives. Parts to repair them are even unobtainium now, forcing people to scavenge old drives for parts. Yet despite the product being introduced in 1991, making some of them over 30 years old, there are THOUSANDS of them still in service around the world.


Must be new math. 2022-2002 = 20 years, not 30.

The PF4 was dropped at about the 10 year mark with no replacement.

The 4/40 have been sold for the last 10 years with the caveat of “replacement only”. AB wanted to sell the PF 753/755/525. You could get a PF 40 if you were persistent. That’s not exactly what I’d consider a “20 year life”. And you are mixing “support” and “design” life.

When AB starts selling a new product like any manufacturer they sign “guaranteed supply” contracts with suppliers for something critical like drive chips. Suppliers usually sign a 10 year contract maximum. At around year 7-8 AB will start to discuss renewals. They’re not going to get 10 years. Maybe say 5 years. At some point though the end is approaching. So they will stockpile enough to cover warranties and repairs. At some point everybody ramps down production. That’s when it will go on “not recommended for new projects” status. Eventually they reach a point where it goes into “service only” status (as in until parts run out). It can be there a LONG time.

At the same time they need drives to sell so it gets kicked over to engineering. They can simply redesign the guts to use whatever the current chips are, possibly with new firmware, and release it with the same model (A vs B version) or maybe market it as the 1336/1336 Plus/1336 Plus 2 with a few new features, or market it as a refreshed design which gave us the 753, 755, and 525 all but displacing the entire 4/40/400 and 70/700 lines.

Knowing that this is the case ideally the VFD is designed to last for whatever the warranty is plus 1 day. But there is a “10 year” expected gap between “generations” just as we see 5 years for PC processors. So the industry norm is 10 years between major redesigns. Hence around 2012 is when the 525 and 750 series appear. We’re already seeing the 755 retired. Given the big changes transitioning to SiC I would expect the 525 to go in a similar direction soon. The “10 year” window us built into everything. Drives have a 100k hour expected life. They use bus capacitors designed for 10 years. The solder joints are intended for 12-15 years.

So if you bought a PF40 in 2002 chances are they had a replacement. If you bought it in 2012, it’s not looking so good. But by 2012 they would have tried to get you to buy say a PF 753 or 500 because marketing was already moving on beyond the PF40s and only selling them as replacements.

For what it’s worth you can buy sintered Semikron modules, same ones used for instance in electric trains. No solder and they use metal film bus caps (no lifespan limit unlike electrolytics). Then if you decrease the operating temperature (oversize components) by 10 C (just double the drive capacity), you get a 200k hour life. At a 300% cost increase. This is not theoretical. These drives exist. Plus the modules can be changed with 3 bolts and a fiber connector, so life isn’t as important as say with a PF40 that is built as a disposable drive from day 1.


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## JRaef (Mar 23, 2009)

paulengr said:


> Must be new math. 2022-2002 = 20 years, not 30.…


You need to read better…



> The PF4 was dropped at about the 10 year mark with no replacement.


I can order a PF4 today, they are still being sold. It’s not being obsoleted until _next_ year. Even then, the PF4M is still available, it’s the same drive except feed-thru wiring (line in the top, load out the bottom).

If you are guessing at things because you are unfamiliar, maybe you should hold back from posting about them…

And by the way, ALL small drives are made as “disposable” now because they ALL use IPMs, making repairs impractical and more expensive than just replacing them. Yes you CAN in theory replace the IPMs, but only if you place no value on your time.


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