Chris, Nice job !! One thing, when you were transfering the wires on the green blocks ( wire for wire) those green blocks are called Euro-blocks, you should be able to pop the top of each section, there are pins under each block, and they plug into the base of each block, It's a time saver.
Gotta give you props on how you went about terminating the VFD. Basically the opposite of careless. Refreshing to see a tech soo methodical and conscientious about his work . These days the big push is "do it faster, just get it done, who cares how it looks" I refuse to work that way and it's good to see someone else apparently thinking along the same lines.
Thanks bud I try my best...I will be going live on RUclips this evening 12/2/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the Chat, RUclips comments, and email’s. Come on over and check it out if you can ruclips.net/video/p3rL6MyXeW4/видео.html
At my warehouse that I take care of I have a strapping machine that has vfd drives. It is also plc driven. This machine is what has taught me a lot about a/c voltage. The vfd's control the motors that feed the strap and tension the strap around the product. In my case we strap tires for the manufacturers ford,chevy, etc. I thank you for showing how you replaced it and using tech support. If I could teach someone about any trade, i would say don't be afraid to call tech support. Being self taught on a lot of things I would say that calling tech support will save you a headache and time. Trying to look things up for an hr when you can get the answer in a few mins is priceless. I found that if you know how to use a multimeter these guys can walk u through about anything electronic or electrical. Thank you for the great videos.
Well you have to use them in screw terminals with fine strand wire in any case, for cage clamps you can get away without them. For the wire connection i would go with ferrules and wago clamps, easy and fast way. Overall that cabinet would never have passed an inspection in germany at any given time.
we have a winner! bad from the start at engineering, maybe lack of factory care (no zip-ties keeping it away from metal) or maybe field techs were to blame :)
I'm taking a class on VFD's for my Automation program in school, and we just got to setting them up in the lab. Lots of reading the manual, and quick start guides and learning what to look for for troubleshooting, and how to program them right now. After 2-3 weeks doing the basics, learning error codes and things we're supposed to start wiring and interfacing with PLC's and networks and I'm really excited for it. We're going through a lot of troubleshooting, and it's one of the things we focus on a lot in this program. Having you going through this kind of stuff, and showing examples of it, and how to fix it really puts the theoretical into context. Even the practical stuff we do gets some grounding with real world and it makes me feel more confident. Some of the stuff we've had hit on us, is of course the importance of incoming power and power to the motor, not getting mixed up. Also have been told that you cannot have a drive fed incoming power through filter capacitors. Thanks for putting out a VFD video. Your troubleshooting and installation videos are always full of great tips and you have a really solid methodology.
My own OCD would probably not allow me to use the demolition screwdriver for anything else than beating on it , kudos for not letting it get to you , Chris !
from the looks of that burnt wiring/plug it was the culprit and started to arc to the cabinet and killed the module. it was probably laying against it and got some water in it (salt water near ocean?) and off went the arcing. did someone work on it and not zip-tie things back into place and away from others? it's more ciritical with VFD driven things, especially at 480AC input levels which exceeds 670VDC pulses, so beware of max wiring, connector and other splicing device voltages. most/many wiring splice devices are rated 600V max! some only 300v. remember VFD stands for (Variable Frequency Drive) and the waveform of the power is nowhere near a nice smooth sine wave as is on 60Hz utility supplied power, it is very abrupt on off pulses, varying in width(on time) on a 480v input, that's over 670VDC pulses, so it's much more likely to strike and sustain and electrical arc and hold them for longer period, vs. direct ac line powered wiring. for blowers and pump they're working in "variable torque" mode. VFD wiring needs special consideration, ratings and implementation, it seems they failed at engineering/implementing on those units :)
I am the same way when I'm installing and doing service calls. I also do dcommercial hvac and sometimes when people observe me they think I'm crazy or weird but I now that I'm not the only one that talks to himself as I'm doing the work
Thank your for this Lennox video,,, i and probably most people of my generation , feel a bit nervous when it comes to working on units laden with modern electronic , inveters and such,,,,i know many of these units give a fault code which tells you what is wrong,, .......but....,,,,,,, Enjoyable video .....
I really love your channel. I'm an electrical engineer from germany and your right, you have to show respect when you're facing a 480V 3phase system. I worked a lot with 690V 3phase here when i worked in automation for big industries like steel mills. Theese days mostly 400V 3phase, what is actually the supply for every private house over here. I wonder that you don't work with end sleeves on stranded wires in the US. Here in Germany you would never connect a VFD directly with stranded wires.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Definitely would be a good idea. Just the fact their using a dirt cheap definite purpose contactor for something that could instantly wreck the drive, shows that they spec'd this to hopefully last the 1 year warranty and they don't really care after that.
Dude, Greetings from Jersey! Excellent job on explaining how to troubleshoot and what not to do. Your on point with this stuff, keep up the great vids!
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Great video, as always great content, I carry the the connectors for R290 units now instead of wire nuts I like the visual and locking the wire in place and preventing moisture. Those VFDS don’t look weather proof should be installed in a conditioned space
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Also with VFD's there's capacitors that take about 20 minutes to drain out. So it's always a good idea to wait at least 20-30 minutes before interacting with it.
14:14 Not a HVAC guy but I was thinking the same. Both contactors should use an interlock, either mechanical or electrical. I mean, You CANT call both of them AT THE SAME TIME. Old relay boards with big three phase contactors used to invert rotation, both contactors were conected mechanically through a crowbar, so Its is one or the other, never both. Sensitive things like this, shouldnt be just SW controlled. A plan B for fail safe is required.
After your wrap up and i went back and looked at those contactors to see for myself. I can't believe Lennox isn't using auxiliary contacts to interlock those two. That is motor controls 101. I wonder how many VFDs they have had to replace under warranty that could have been prevented with a pair of $10 aux contacts.
I suspect that the way it works is you have one contactor feeding 480 to the input to the VFD, and the second contactor connecting the input of the VFD to it's output, shorting across it. So to bypass and power the motor you need to pull both of them in at once. But you probably want to drop the main contactor before you pull in the bypass contactor. Then the VFD can't do anything and is safe. But if the VFD is running and you pull in the bypass contactor you make popcorn some fraction of the time.
Agreed, also wondering why they haven't gone to solid state contactors. with the amount of airborne contaminants in and around RTU's it would boost reliability. Again, it's old tech at this point.
Even if they had interlocking contacts there would be a problem switching from on power source to another so quickly with a running motor. The compressor will be running at whatever speed the system called for - if the system senses a problem and goes directly to bypass - the compressor will have slowed slightly from its speed and is generating a back emf voltage - the voltage the compressor is generating and the voltage from the bypass contact will be out of phase with whatever the compressor is generating and there will be a very high fault current generated for a fraction of a second ... I have seen all kinds of coupling failures - breaker trips and other electrical damage from transferring between two electrical systems too quickly. It's the same thing as transferring the load from a generator back to the utility after a test - you have to wait till your motors stop turning to retransfer ... if you have a blink in power the drives have programming that you can decide what you want to do . You can wait and restart - you can wait for another start command or you can catch the motor "on the fly" - automatic transfer switches have what they call a programmable neutral time. So without that delay time in the bypass relay there will be problems. Faults generated like this cause the windings in the motors to flex - the flexing will cause the windings to fail where the copper windings enters the motor steel - it's called a slot failure.
I agree with the aux contacts. The software most likely switches both contactors at the same time. An aux contact will require the first one to be deenergized before the second makes contact.
Interesting design. Lennox should have used a reversing contactor setup. If one side is on there is a Electrical interlock using Auxilliary contacts, along with a Mechanical interlock between the contactors. Good practice with the 480 connections. I take a pictures using a cell phone of the connections at different angles as a backup. Regarding arc flash if low peak fuses are used with proper wiring I am more secure. With a breaker then watch out. Breakers can put out 12 cycles before tripping. Low peak fuses open at the first 1/3 of a cycle if shorted. They are also expensive. :-)
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Just for those who are not aware, those vfd’s can hold a lethal charge up to 5 minutes. I personally usually wait about 15 minutes to touch any wires when changing one out. The manual always has the info about how long to wait when changing a vfd. Don’t want anyone out there learning the hard way
It seems weird that Lenox would sell the VFD without the wiring attached. It also seems insane that they use the same colors and connectors for the input and output harnesses.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
VFDs are typically designed for 80 F ambient and start derating their output above this temperature. They should not be in a package unit on a 110F roof. Way over it’s specification. Look at the data sheet and you will be shocked! A 10hp vfd cannot output 10hp at 100f. VFDs also contain electrolytic capacitors which fail faster in proportion to their increase in temperature, higher ambient temps = significantly shorter lifespans. This is often a source of failure, as IGBTs are sensitive to dirty power
Vega they have cooling fans and most likely will be in the supply air side of the package unit. I had one fail last week. It was caused by moister. Mixing 460v and moister is not a good thing. I installed a dog house over the new VFD. The cooling fan will circulate around the drive to help keep it dry. ABB drives should have the cooling fans changed every 6 years. I just learned that from the ABB rep.
ACtech Formally yo mama while true don’t forget to think about startup on a hot day, the drive will be heat soaked, and the caps will be baking out their liquid electrolytics, and be derating on startup until the temps come down. This is a poorly designed system if they’re using a bypass contactor installed from the factory to detect a failed drive. Drives are either undersized, receiving dirty power, overheating/derating, etc. if you’re factory installing a bypass contactor, you shouldn’t be using a vfd, period. And btw for sure on the fan, it’s another maintenance item with a vfd
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
You do some good work. However instead of using electrical tape on those butt connectors it would be better to use adhesive lined heat shrink. I also would have cut those wires back so that the insulation came all the way up to the screw terminals.
I work on high voltage all the time up to 13800 volts. I respect all your videos and your OCD. The manufacturer has a torque spec for line connections. You turned in then turned out then turned in. Was the torque wrench in your arm clicking
Also at an added note 120v kills way more people than 277/480. A 480 v unit runs lower amps and arc flash potential when apple's are compared to apple's 120v will have a larger arc flash potential.
They are very durable, oftentimes it's how the OEM put them into their units or how they are protected externally. Most of the times they don't even have a line filter on them.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
If the bypass contactor can backfeed the VFD, then they did it really wrong! They may have used the wrong contactor type, or cheaped out or something... You should have a normally open and normally closed contacts... Motor should go to the common, VFD output to the NC and power to NO. This way, there is no way for the VFD to get backfeeded, the contacts will break before it make with the other, and you can not get a short between NC and NO unless the contactor melt down...
I will discuss this on my livestream tonight, I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
VFD output is a very harsh and hard to deal with power, at 480VAC input it 670+VDC output pulses varied in width(on time) and there's equally as harsh or worse back EMF from the motor/s, so they'd need to use special, wiring, contactor and splices to withstand that properly. the whole issue is, they're using common junk rated for AC on PWM DC, where it should have never been used. even those nylon quick disconnect plugs are suspect looking :)
Don't those green contact strips in the vfd just unplug? They should use a relay that opens the circuit to the vfd when it bypasses it. A 3 phase reversing contactor could be used with a slight modification.
I would think that there should be interlock on bypass contactor that would take vfd out of the circuit. But it looks that manufacturers like to make better margin and leave that safety to software.
I'm surprised that those run and bypass contractors are not electrically interlocked. A VFD out put is not a sine wave - if you ever look at a vfd output on an O scope it will scare you to death. A vfd not only varies the frequency of the output it also vary the voltage - so if your speed is 50% your motor will be turning at 30 Hertz your voltage will also be 50% - so you can see what would happen if you bypassed the drive that was running at a reduced speed not only would you be closing two electrical systems into each other at different frequencies they would also be operating at different voltages - and to add more destruction to the mix there is the phase relationship difference that the drive creates - when a drive takes its input voltage it converts it to DC- then the drive fires the triacs according to what the drive software is calling for - even if both systems are operating at 60 Hertz the drive input and output will not be Synronized - the more electrical degrees apart the two systems are determines the amount of fault current that will be generated. That is what blew up that drive I'm sure. I have seen huge breakers launch out of switch gear and hit the wall because phase rotation was not correct on a 4000 hp generator that generates 2.5 megawatts of power at 4160 volts. What they have designed is a bomb waiting to blow up in somebody's face. I would disable that bypass relay so there would be no way it could supply power to the output of the drive - I would mark the phase rotation and disconnect the power to the bypass relay - then if you need it you could disconnect the input from the drive and reconnect the bypass relay. And if you need the bypass relay I would also disconnect the output of the drive - you will be backfeeding into the drive when your bypass relay is energized... judging from this video I would not let any employees mess with it. Everyone needs to understand exactly what forces are in play with two out of phase power sources... if you want to verify what I'm saying next time you get around one of these drives put your meter on voltage and put one lead on A phase input and the other lead on A phase output - if they were in sinc the meter will read 0 volts - any voltage reading indicates how far out of sync the input and output are - with a little math you can figure out how many electrical degrees out of sync the two systems are. Good luck
JT H - And that’s just V/Hz drives... Sensorless Vector Drives are even more complicated. The manual for every VFD I’ve ever seen states that you’re not supposed to use contactors... direct hardwire to the motor only. 🤨 Oh, and FWIW it’s not triacs in the drive; it’s usually IGBTs... although some older and/or smaller units have used MOSFETs... triacs depend on the input power going thru zero to switch off (so when it’s used on a AC source, it’s not a problem; but connected to the DC bus of the VFD there would be no way for the triac to turn off). 🙂
@@darkwinter6028 I have found several contactors involved with vfd systems with their contacts welded closed.. lol those contacts dont like the high frequency voltage spikes associated with vfd. The contactors were emergency shutdown contactors that were supposed to shutdown all the fuel pumps at a big name brand filling station. I was contracted to check the functionality of all the safety systems at several different stations - I found failures at each station. These systems were manufactured and purpose built with UL labels and built by a UL 508 panel shop. I notified the manufacturer- the fire department and the electrical inspector .. that type of design will no longer get past electrical plan approval in that city. I was surprised that the designers did not put filters on the input of the drives to filter the commutation spikes from the drives out of the supply voltage.
I do have a question. Are outdoor condenser units on a drinks fridge/cool room suppose to produce / blow condensation and therefore create mould on the surrounding area?
Next time use your cell to watch the unit startup and stand aside from the access panel and the disconnect switch. In this case it would have been better to stand further down the side of the unit away from anything that could go boom. Backing up and turning your head will not help, if anything happens it will happen so fast that it is like dodging laser beams. Hopefully one day you be driving home with a destroyed cell phone and amazed at how fast the whole thing went sideways, but you are fine and just need to replace your cell. You have a tripod so you could have used it for keeping an eye on the startup.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Great job. Do you think that in the hot dessert area that you service in, it pays to have VFD's installed? I would guess that they run wide open most of the time. Thoughts?
Bypass contactors should be both electrically and mechanically interlocked especially if used around a VFD - secondly is it possible that the original VFD was actually not faulty at all and the problem the motor supply cables that where shorted on the cover ?? Most VFD are very well protected for shorted output.
I'd guess they didn't ziptie the wiring and plug away from the case/cover or someone cut them off, it got wet from rain(near ocean/salt water worse) that let it strike an arc easily, in which it kept burning happily until it went ka-boom. vfd wiring needs special consideration, it's very rough high voltage pulses, at 480VAC input, that's 670+VDC output in high speed pulses. which is also beyond the rating and spec of many common wiring and wire splicing devices and techniques. there's probable multiple failures scenario's there, from engineering, through factory, to previous field service technician's :)
I'm changing a carrier ruftop unit bloower motor the new motor has its 3 hp. It's same model..and number. The blue wires 2 coming out fron the motor. Has fimale and male ..to connect the the red wires goit to the control .. but this red wires has only males..adaptes.... so only 1 gets conested quet about the other ..the old motor it wasn't this motor its fron marathon motors..like this. Any suggestions.?.?
a bit late to the party maybe, but why are those contactors not wired like a logic XOR gate? basically like the cooler/defrost interlock, except on both contactors? If I understand those things correctly, that way they'd only allow one to be energized, and never both...
Good question they certainly should be! I will be going live on RUclips this evening 12/30/19 @5:PM (pacific time) to discuss my most recent uploads and answer questions from emails and the chat, come check it out if you can ruclips.net/video/XNnsDZUitZQ/видео.html
I think that actual ouput freq is 59Hz. VFD are supposed to change the freq to control de speed of the AC motor. Looks like it settle at 59 but the VFD will change that on demand, to iddle the motor or make it run faster.
I was looking at that on the 480v wire and motor wires. I would think the insulation should stop at the screw terminal. I have so many installs that have so much bare wire showing, that they short together if bent just right.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
The drive failure on these I have seen is heat. The manufacturer did not design these to run in the heat your region has. If u look at what the vfd is rated for and temperature you will see inevitably they will fail
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
![Twenty One Pilots - “The Line” (from Arcane Season 2) [Official Music Video]](http://i.ytimg.com/vi/E2Rj2gQAyPA/mqdefault.jpg)
Was waiting for a video today thank you!
Chris, Nice job !! One thing, when you were transfering the wires on the green blocks ( wire for wire) those green blocks are called Euro-blocks, you should be able to pop the top of each section, there are pins under each block, and they plug into the base of each block, It's a time saver.
Gotta give you props on how you went about terminating the VFD. Basically the opposite of careless. Refreshing to see a tech soo methodical and conscientious about his work . These days the big push is "do it faster, just get it done, who cares how it looks" I refuse to work that way and it's good to see someone else apparently thinking along the same lines.
Thanks bud I try my best...I will be going live on RUclips this evening 12/2/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the Chat, RUclips comments, and email’s. Come on over and check it out if you can ruclips.net/video/p3rL6MyXeW4/видео.html
At my warehouse that I take care of I have a strapping machine that has vfd drives. It is also plc driven. This machine is what has taught me a lot about a/c voltage. The vfd's control the motors that feed the strap and tension the strap around the product. In my case we strap tires for the manufacturers ford,chevy, etc. I thank you for showing how you replaced it and using tech support. If I could teach someone about any trade, i would say don't be afraid to call tech support. Being self taught on a lot of things I would say that calling tech support will save you a headache and time. Trying to look things up for an hr when you can get the answer in a few mins is priceless. I found that if you know how to use a multimeter these guys can walk u through about anything electronic or electrical. Thank you for the great videos.
Your troubleshooting procedures should be the gold standard
You are starting to look very tired my friend. You need a vacation! Thanks for another interesting video for us HVACR enthusiasts
This video was shot a few years ago and I still haven't taken a proper vacation...... im much more grey in the face now too!
In Germany we normally use ferrules. This makes it easyer to prevent arcs between the connected wires 😉
Well you have to use them in screw terminals with fine strand wire in any case, for cage clamps you can get away without them. For the wire connection i would go with ferrules and wago clamps, easy and fast way.
Overall that cabinet would never have passed an inspection in germany at any given time.
we have a winner! bad from the start at engineering, maybe lack of factory care (no zip-ties keeping it away from metal) or maybe field techs were to blame :)
I love those ferules but cant get them in the Caribbean for a cost thats worth it. Was certified by Aachen chamber of crafts
I suspect that the short you found is what blew the VFD. With that kind of power, the bang at the VFD is going to be big in quite a bit of the cases.
I'm taking a class on VFD's for my Automation program in school, and we just got to setting them up in the lab. Lots of reading the manual, and quick start guides and learning what to look for for troubleshooting, and how to program them right now. After 2-3 weeks doing the basics, learning error codes and things we're supposed to start wiring and interfacing with PLC's and networks and I'm really excited for it. We're going through a lot of troubleshooting, and it's one of the things we focus on a lot in this program. Having you going through this kind of stuff, and showing examples of it, and how to fix it really puts the theoretical into context. Even the practical stuff we do gets some grounding with real world and it makes me feel more confident.
Some of the stuff we've had hit on us, is of course the importance of incoming power and power to the motor, not getting mixed up. Also have been told that you cannot have a drive fed incoming power through filter capacitors. Thanks for putting out a VFD video. Your troubleshooting and installation videos are always full of great tips and you have a really solid methodology.
Thank you again the old videos are just as good !!!
My own OCD would probably not allow me to use the demolition screwdriver for anything else than beating on it , kudos for not letting it get to you , Chris !
480 volts proceed with caution. Your a very smart tech, one wrong move and it will spell disaster. Great video.
I wonder if Big Clive would be interested in looking at those VFD modules? 🤔
Not sure what shipping would be like to the Isle of Man though lol
YES! Please yes! Didnt clive do refrigeration at one point too?
from the looks of that burnt wiring/plug it was the culprit and started to arc to the cabinet and killed the module. it was probably laying against it and got some water in it (salt water near ocean?) and off went the arcing. did someone work on it and not zip-tie things back into place and away from others? it's more ciritical with VFD driven things, especially at 480AC input levels which exceeds 670VDC pulses, so beware of max wiring, connector and other splicing device voltages. most/many wiring splice devices are rated 600V max! some only 300v.
remember VFD stands for (Variable Frequency Drive) and the waveform of the power is nowhere near a nice smooth sine wave as is on 60Hz utility supplied power, it is very abrupt on off pulses, varying in width(on time) on a 480v input, that's over 670VDC pulses, so it's much more likely to strike and sustain and electrical arc and hold them for longer period, vs. direct ac line powered wiring. for blowers and pump they're working in "variable torque" mode.
VFD wiring needs special consideration, ratings and implementation, it seems they failed at engineering/implementing on those units :)
That would be the RUclips crossover of the century lol
I am the same way when I'm installing and doing service calls. I also do dcommercial hvac and sometimes when people observe me they think I'm crazy or weird but I now that I'm not the only one that talks to himself as I'm doing the work
Thank your for this Lennox video,,, i and probably most people of my generation , feel a bit nervous when it comes to working on units laden with modern electronic , inveters and such,,,,i know many of these units give a fault code which tells you what is wrong,, .......but....,,,,,,,
Enjoyable video .....
I really love your channel. I'm an electrical engineer from germany and your right, you have to show respect when you're facing a 480V 3phase system. I worked a lot with 690V 3phase here when i worked in automation for big industries like steel mills. Theese days mostly 400V 3phase, what is actually the supply for every private house over here. I wonder that you don't work with end sleeves on stranded wires in the US. Here in Germany you would never connect a VFD directly with stranded wires.
Tip for using but connectors, use some silicone filled heat shrink over the top to keep moisture out and protect others if the plastic cracks.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Sounds like they need a mechanical interlock to avoid that problem. Great video.
Definitely would be a good idea. Just the fact their using a dirt cheap definite purpose contactor for something that could instantly wreck the drive, shows that they spec'd this to hopefully last the 1 year warranty and they don't really care after that.
Good point
Should of had NEMA rated contactors.. just shows the level of engineering degrees Lennox employs at its facility
Thanks for the information. I work on a lot yorks that have a VFD and they can get tricky. Yorks VFD looks very similar to the one you changed out.
Dude, Greetings from Jersey! Excellent job on explaining how to troubleshoot and what not to do. Your on point with this stuff, keep up the great vids!
Thanks so much for watching!
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Great video, as always great content, I carry the the connectors for R290 units now instead of wire nuts I like the visual and locking the wire in place and preventing moisture. Those VFDS don’t look weather proof should be installed in a conditioned space
Great video and good way to approach the replacement
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Nice and simple explanation and thinking process 👊🏼
Also with VFD's there's capacitors that take about 20 minutes to drain out. So it's always a good idea to wait at least 20-30 minutes before interacting with it.
14:14 Not a HVAC guy but I was thinking the same. Both contactors should use an interlock, either mechanical or electrical. I mean, You CANT call both of them AT THE SAME TIME. Old relay boards with big three phase contactors used to invert rotation, both contactors were conected mechanically through a crowbar, so Its is one or the other, never both. Sensitive things like this, shouldnt be just SW controlled. A plan B for fail safe is required.
After your wrap up and i went back and looked at those contactors to see for myself. I can't believe Lennox isn't using auxiliary contacts to interlock those two. That is motor controls 101. I wonder how many VFDs they have had to replace under warranty that could have been prevented with a pair of $10 aux contacts.
I share your observation. Such a simple fix to prevent energizing two contactors at the same time!!
I suspect that the way it works is you have one contactor feeding 480 to the input to the VFD, and the second contactor connecting the input of the VFD to it's output, shorting across it. So to bypass and power the motor you need to pull both of them in at once. But you probably want to drop the main contactor before you pull in the bypass contactor. Then the VFD can't do anything and is safe. But if the VFD is running and you pull in the bypass contactor you make popcorn some fraction of the time.
Agreed, also wondering why they haven't gone to solid state contactors. with the amount of airborne contaminants in and around RTU's it would boost reliability. Again, it's old tech at this point.
Even if they had interlocking contacts there would be a problem switching from on power source to another so quickly with a running motor. The compressor will be running at whatever speed the system called for - if the system senses a problem and goes directly to bypass - the compressor will have slowed slightly from its speed and is generating a back emf voltage - the voltage the compressor is generating and the voltage from the bypass contact will be out of phase with whatever the compressor is generating and there will be a very high fault current generated for a fraction of a second ... I have seen all kinds of coupling failures - breaker trips and other electrical damage from transferring between two electrical systems too quickly. It's the same thing as transferring the load from a generator back to the utility after a test - you have to wait till your motors stop turning to retransfer ... if you have a blink in power the drives have programming that you can decide what you want to do . You can wait and restart - you can wait for another start command or you can catch the motor "on the fly" - automatic transfer switches have what they call a programmable neutral time. So without that delay time in the bypass relay there will be problems. Faults generated like this cause the windings in the motors to flex - the flexing will cause the windings to fail where the copper windings enters the motor steel - it's called a slot failure.
I agree with the aux contacts. The software most likely switches both contactors at the same time. An aux contact will require the first one to be deenergized before the second makes contact.
Interesting design. Lennox should have used a reversing contactor setup. If one side is on there is a Electrical interlock using Auxilliary contacts, along with a Mechanical interlock between the contactors. Good practice with the 480 connections. I take a pictures using a cell phone of the connections at different angles as a backup. Regarding arc flash if low peak fuses are used with proper wiring I am more secure. With a breaker then watch out. Breakers can put out 12 cycles before tripping. Low peak fuses open at the first 1/3 of a cycle if shorted. They are also expensive. :-)
Good detail to attention and safety practice. Job well done. Yes I talk to my self as I work seams to help think things through
Very well done !
It is finally starting to get cold 🥶
Nice weather for repair. I was rarely that lucky.
Great video Chris.
"Hooking them up wrong causes the unit to explode" Proceeds to hook up the new part in the same way. You are trusting.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
I always talk to my self when do trouble shooting, so its pretty normal 😂
Checking you out from Alabama ,thanks
Just for those who are not aware, those vfd’s can hold a lethal charge up to 5 minutes. I personally usually wait about 15 minutes to touch any wires when changing one out. The manual always has the info about how long to wait when changing a vfd. Don’t want anyone out there learning the hard way
Great job again like always
It seems weird that Lenox would sell the VFD without the wiring attached. It also seems insane that they use the same colors and connectors for the input and output harnesses.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
VFDs are typically designed for 80 F ambient and start derating their output above this temperature. They should not be in a package unit on a 110F roof. Way over it’s specification. Look at the data sheet and you will be shocked! A 10hp vfd cannot output 10hp at 100f. VFDs also contain electrolytic capacitors which fail faster in proportion to their increase in temperature, higher ambient temps = significantly shorter lifespans. This is often a source of failure, as IGBTs are sensitive to dirty power
Vega they have cooling fans and most likely will be in the supply air side of the package unit. I had one fail last week. It was caused by moister. Mixing 460v and moister is not a good thing. I installed a dog house over the new VFD. The cooling fan will circulate around the drive to help keep it dry. ABB drives should have the cooling fans changed every 6 years. I just learned that from the ABB rep.
ACtech Formally yo mama while true don’t forget to think about startup on a hot day, the drive will be heat soaked, and the caps will be baking out their liquid electrolytics, and be derating on startup until the temps come down. This is a poorly designed system if they’re using a bypass contactor installed from the factory to detect a failed drive. Drives are either undersized, receiving dirty power, overheating/derating, etc. if you’re factory installing a bypass contactor, you shouldn’t be using a vfd, period. And btw for sure on the fan, it’s another maintenance item with a vfd
Aaand you forgot the sticker..😂 8:15
Nice repair video 👍
i remember that you could pull out the entire green wire bar, the one with the push releases.
Just an observation looks like you’re using a Klein demolition screwdriver that end cap is conductive
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
it only hurts a little.......
@@throttlebottle5906 😆 😅 😂 🤣
Thanks, Great Info
Those VFD's are a big money maker!
Yes they are!
I seen you check for no power before starting, but did you check your meter before on a know voltage?
I'm going to lose some sleep after seeing those white cable ties being uncut.
That’s a WHOLE LOT of Volts!!
Still waiting for the Volunteer Fire Department to arrive!
Yes amigo
Some VFDs will have stored power in the drive...They power down after short time main power off.. i also use a volt stick on the drive also..
Thanks🙂nice video
Wire termination is your friend ;-)
You do some good work. However instead of using electrical tape on those butt connectors it would be better to use adhesive lined heat shrink. I also would have cut those wires back so that the insulation came all the way up to the screw terminals.
I suppose the VFD feeding one phase shorted to ground is all that it takes to takes to spoil it's day. Ron W4BIN
I work on high voltage all the time up to 13800 volts. I respect all your videos and your OCD. The manufacturer has a torque spec for line connections. You turned in then turned out then turned in. Was the torque wrench in your arm clicking
Also at an added note 120v kills way more people than 277/480. A 480 v unit runs lower amps and arc flash potential when apple's are compared to apple's 120v will have a larger arc flash potential.
@@davidhaynes98 that's only cause very few people playing w460 v. Try shorting out 460 v.
First like and comment I wish VFDS were more durable
They are very durable, oftentimes it's how the OEM put them into their units or how they are protected externally. Most of the times they don't even have a line filter on them.
I have changed the same Mitsu VFD in a York. F700 I think.....
Very smart great
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
If the bypass contactor can backfeed the VFD, then they did it really wrong!
They may have used the wrong contactor type, or cheaped out or something...
You should have a normally open and normally closed contacts... Motor should go to the common, VFD output to the NC and power to NO. This way, there is no way for the VFD to get backfeeded, the contacts will break before it make with the other, and you can not get a short between NC and NO unless the contactor melt down...
I will discuss this on my livestream tonight, I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
VFD output is a very harsh and hard to deal with power, at 480VAC input it 670+VDC output pulses varied in width(on time) and there's equally as harsh or worse back EMF from the motor/s, so they'd need to use special, wiring, contactor and splices to withstand that properly.
the whole issue is, they're using common junk rated for AC on PWM DC, where it should have never been used. even those nylon quick disconnect plugs are suspect looking :)
Don't those green contact strips in the vfd just unplug? They should use a relay that opens the circuit to the vfd when it bypasses it. A 3 phase reversing contactor could be used with a slight modification.
I would think that there should be interlock on bypass contactor that would take vfd out of the circuit. But it looks that manufacturers like to make better margin and leave that safety to software.
Does the control use the pressure switch attached to the blower housing to determine if the blower is working?
Just thinking you didn’t mention a lock out on the bypass
Shouldn’t there be a lockout to prevent that on the contactor ?
I'm surprised that those run and bypass contractors are not electrically interlocked. A VFD out put is not a sine wave - if you ever look at a vfd output on an O scope it will scare you to death. A vfd not only varies the frequency of the output it also vary the voltage - so if your speed is 50% your motor will be turning at 30 Hertz your voltage will also be 50% - so you can see what would happen if you bypassed the drive that was running at a reduced speed not only would you be closing two electrical systems into each other at different frequencies they would also be operating at different voltages - and to add more destruction to the mix there is the phase relationship difference that the drive creates - when a drive takes its input voltage it converts it to DC- then the drive fires the triacs according to what the drive software is calling for - even if both systems are operating at 60 Hertz the drive input and output will not be Synronized - the more electrical degrees apart the two systems are determines the amount of fault current that will be generated. That is what blew up that drive I'm sure. I have seen huge breakers launch out of switch gear and hit the wall because phase rotation was not correct on a 4000 hp generator that generates 2.5 megawatts of power at 4160 volts. What they have designed is a bomb waiting to blow up in somebody's face. I would disable that bypass relay so there would be no way it could supply power to the output of the drive - I would mark the phase rotation and disconnect the power to the bypass relay - then if you need it you could disconnect the input from the drive and reconnect the bypass relay. And if you need the bypass relay I would also disconnect the output of the drive - you will be backfeeding into the drive when your bypass relay is energized... judging from this video I would not let any employees mess with it. Everyone needs to understand exactly what forces are in play with two out of phase power sources... if you want to verify what I'm saying next time you get around one of these drives put your meter on voltage and put one lead on A phase input and the other lead on A phase output - if they were in sinc the meter will read 0 volts - any voltage reading indicates how far out of sync the input and output are - with a little math you can figure out how many electrical degrees out of sync the two systems are. Good luck
JT H - And that’s just V/Hz drives... Sensorless Vector Drives are even more complicated. The manual for every VFD I’ve ever seen states that you’re not supposed to use contactors... direct hardwire to the motor only. 🤨
Oh, and FWIW it’s not triacs in the drive; it’s usually IGBTs... although some older and/or smaller units have used MOSFETs... triacs depend on the input power going thru zero to switch off (so when it’s used on a AC source, it’s not a problem; but connected to the DC bus of the VFD there would be no way for the triac to turn off).
🙂
@@darkwinter6028 I have found several contactors involved with vfd systems with their contacts welded closed.. lol those contacts dont like the high frequency voltage spikes associated with vfd. The contactors were emergency shutdown contactors that were supposed to shutdown all the fuel pumps at a big name brand filling station. I was contracted to check the functionality of all the safety systems at several different stations - I found failures at each station. These systems were manufactured and purpose built with UL labels and built by a UL 508 panel shop. I notified the manufacturer- the fire department and the electrical inspector .. that type of design will no longer get past electrical plan approval in that city. I was surprised that the designers did not put filters on the input of the drives to filter the commutation spikes from the drives out of the supply voltage.
I do have a question. Are outdoor condenser units on a drinks fridge/cool room suppose to produce / blow condensation and therefore create mould on the surrounding area?
Any condensation on connectors with 480 VAC might as well be a short!
Being it's in the compressor area for sure
@@FlyEaglesFly19111 It is the best place to put your VFD, thermal cycling, humidity and vibration.
Next time use your cell to watch the unit startup and stand aside from the access panel and the disconnect switch. In this case it would have been better to stand further down the side of the unit away from anything that could go boom. Backing up and turning your head will not help, if anything happens it will happen so fast that it is like dodging laser beams. Hopefully one day you be driving home with a destroyed cell phone and amazed at how fast the whole thing went sideways, but you are fine and just need to replace your cell. You have a tripod so you could have used it for keeping an eye on the startup.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
great video
I love it ......is the allergy is killing you...lol.....I have the same problem
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Great job. Do you think that in the hot dessert area that you service in, it pays to have VFD's installed? I would guess that they run wide open most of the time. Thoughts?
Why is it 480V, seems a weird voltage.
Thinking about it, im guessing its a safety measure for the PCB. 🤔
I wonder if that short on the output of the VFD was what turned it into popcorn.
Was wondering the same, looks like the smoking gun IMO.
Interesting
Bypass contactors should be both electrically and mechanically interlocked especially if used around a VFD - secondly is it possible that the original VFD was actually not faulty at all and the problem the motor supply cables that where shorted on the cover ?? Most VFD are very well protected for shorted output.
I'd guess they didn't ziptie the wiring and plug away from the case/cover or someone cut them off, it got wet from rain(near ocean/salt water worse) that let it strike an arc easily, in which it kept burning happily until it went ka-boom.
vfd wiring needs special consideration, it's very rough high voltage pulses, at 480VAC input, that's 670+VDC output in high speed pulses. which is also beyond the rating and spec of many common wiring and wire splicing devices and techniques. there's probable multiple failures scenario's there, from engineering, through factory, to previous field service technician's :)
Throw that skew driver almost eletrcuted myself with chisel driver easy to absent mindendly use on live circuit
Remember that you had to clean the coils on that unit?
i like those styled packaged units
👍
Smarter not harder
can i have tho old vfd module???? but ur video is awsome.
I have the same screwdriver
I like to install ferrules on this cables
So... why didn't those wires have any ferrules or terminals on them?
Auxiliary switch on vfd contactor wired nc to interlock with the bypass contactor. Advise Lenox.
Nice video btw 👍
@@johnt7502 SHHHHHHHHH we need to sell VFDs !!!!!!
Maybe lennox should wire in a relay that would disable the drive contactor if and when the bypass energizes.
Normally closed relay to drive contactor control wire that opens when power is sent from bypass contactor
why did they not use wire ferrules?
I'm changing a carrier ruftop unit bloower motor the new motor has its 3 hp. It's same model..and number. The blue wires 2 coming out fron the motor. Has fimale and male ..to connect the the red wires goit to the control .. but this red wires has only males..adaptes.... so only 1 gets conested quet about the other ..the old motor it wasn't this motor its fron marathon motors..like this. Any suggestions.?.?
a bit late to the party maybe, but why are those contactors not wired like a logic XOR gate?
basically like the cooler/defrost interlock, except on both contactors? If I understand those things correctly, that way they'd only allow one to be energized, and never both...
Good question they certainly should be! I will be going live on RUclips this evening 12/30/19 @5:PM (pacific time) to discuss my most recent uploads and answer questions from emails and the chat, come check it out if you can
ruclips.net/video/XNnsDZUitZQ/видео.html
Is it possible to bypass a VFD on a Lennox unit with a 3 pole contactor?
it is sad to say but how long will it be before you are back replacing that or any new VFD agene?
👍👍
Even in residential applications i have a lot of problems with those drives. They are garbage
Can someone explain why you’d need a vfd for 59hz? When standard line voltage is 60hz?
I think that actual ouput freq is 59Hz. VFD are supposed to change the freq to control de speed of the AC motor. Looks like it settle at 59 but the VFD will change that on demand, to iddle the motor or make it run faster.
You could strip the wires a little shorter.
I was looking at that on the 480v wire and motor wires. I would think the insulation should stop at the screw terminal. I have so many installs that have so much bare wire showing, that they short together if bent just right.
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
Was the replacement part made by Mitsubishi Electric?
Yes
Thanks. I knew Mitsubishi was working with Trane but was unaware Lennox used Mitsubishi parts. Enjoy and thanks
you did reveal something, but editing must take time
The drive failure on these I have seen is heat. The manufacturer did not design these to run in the heat your region has. If u look at what the vfd is rated for and temperature you will see inevitably they will fail
I will be going live on RUclips this evening 9/30/19 @ 5:PM (pacific time) to discuss my most recent uploads and answer questions from the LiveChat, RUclips comments, Emails, and Facebook comments come check it out if you can. ruclips.net/video/ZAA19Gt7NEo/видео.html
I bet the short is the reason tbe vfd went ... pop....
So do I.
Why is it a Mitsubishi VFD?
#156 Thumbs Up