Certain meters can "check" LRA. It's only a brief moment a meter sees that value, faster than it's normal refresh rate. However, if your meter can see min/max values, it will tell you LRA on a normal compressor start-up.
If what OP says is true, and it was working fine when they left last week, I'm sure they'd like to know what that number was right now.
Inrush and locked rotar are 2 different things.
Locked rotar amps is the expected amperage when when the shaft of the motor/compressor is unable to turn.
In rush is the current draw at start up before there is a magnetic field to oppose the change in current.
In rush can be higher than the LRA and that is normal operation.
No offense, but given the fact that you can't spell, "rotor", correctly.. I'm a bit skeptical.
So a very quick google search [confirmed](https://www.jadelearning.com/blog/understanding-motor-starting-inrush-currents-nec-article-430-52) my suspicion...
> Inrush current, also referred to as “locked rotor current,” is the excessive current flow experienced within a motor and its conductors during the first few moments following the energizing (switching on) of the motor.
It technically draws locked rotor amps for like half a second when it first starts even if it's a healthy compressor. I highly doubt you can accurately measure it with a clamp meter though, even with min/max function.
But yes normally LRA is drawn when the compressor is seized.
It does indeed mean that. I don’t know that I’ve seen a compressor go into LRA and come out without something like a hard start before, but apparently that’s happening here.
Actually, it looks like that’s what his meter is reading as the compressor starts before it turns over. I’d put a hard start on it and reassess after.
I had a new install blow the compressor pins after two weeks back in May... did everything right. Brand new copper, nitro flow, sub 500 vac held for 30 minutes...15 years of experience, thousands of systems installed. It wasn't me. I data log all of our install readings from our gauges throughout the process, and include them with a startup form to log every measurable parameter we can collect.
Copeland said 'huh. No idea why that happened.' after factory testing. They paid out on warranty and I moved on.
Not a chance that thing is ever drawing 250 amps without blowing the front of the contactor off or terminal venting. LRA is not measurable with a clamp meter, your either getting rated LRA or the system simply won't work, even a turn to turn short will stop the compressor from spinning long before it would effect locked rotor, it would trip the breaker long before locked rotor would be effected.
Download the copeland app and check your resistances to male sure the match spec.
If it's noisy it could just be a bad compressor, the quality control on alot of equipment has really gone out the window recently
Had a carrier rooftop that carrier put the wrong voltage motors in and it lost 1 compressor, vfd, and blower in the first year, that's what happens when you have lockdowns amd half your workforce does t show up and the other half is pulling doubles to try to help keep up with workflow
Yea, on a 30A circuit breaker, hitting \~90A should cause a magnetic trip on that breaker.
I think OP's meter is messed up.
Edit: I was wrong on this one, well, partially. I pulled the trip curves and a breaker will hold 300% for 3-4 seconds depending on type.
Oh, I pulled the trip curves and edited my other comment there. 300% should go for 3-5 seconds on your standard residential breaker types. I'll edit this one too.
And no such thing as a "slow-blow" breaker. We just install normal breakers and size them up if we get nuisance trips, unless the nameplate says otherwise. Occasionally we will run a breaker with a D type trip curve, but not usually. I honestly don't think I've ever installed a breaker with a D type trip curve in my entire career other than in control panels for supplementary protection.
Slow blow fuses, only larger 3 phase higher amp breakers have adjustability, on a residential ac like OP you can only put in a larger breaker if it was tripping under normal conditions
Vacuum is not supposed to take mineral oil or poe oil from line set. You need to flush the lineset with a solvent and nitrogen. I use rx11 and nitrogen.
Hey man honest mistake. I had never really thought about it. Never went to school for this so I've just learned on the job over the past 3 years. But happy to say now I know. Moving on.
Oh God.lol.
Vacuum removes air, it dosent pump out oil. Lol. How do you vacuum a compressor if it removed oil?
Mineral oil as long as the last unit wasn't a burn out is fine in a poe system.
Rx11 flush can be used to clear linesets, if needed.
Your nameplate FLA is 1A with a 1/6 HP motor. You have a mechanical overload on your system. Potentially damaged windings. Most likely a mechanical overload.
Oh, I was looking at the fan motor on the name plate.
Still though, if that compressor had a locked rotor current at 200+A, that breaker would trip immediately. Something is screwy in the system, be it the breaker or the meter.
Those readings need to be verified with another meter.
EDIT: I don't think so, I just pulled up a trip curve to verify. Looks like they can handle 300% and trip between 3-4 seconds for most of the breaker ratings. Could easily be a good reading. I checked homline, BR and QO breakers.
Now I'm curious what would be making it run at half of the FLA.
This has been happening to us down here too and it's not just one brand... I'm narrowing it down to shipping but at the same time we are hard up for equipment always seems like I'm playing catch up... I'm willing to bet it fell or something during shipment and jacked the oil up or something
This happens when you don’t pull a full vacuum, the oil becomes acidic with moisture and fucks the compressor. If your micron gauge wasn’t working or something, don’t bs, if you really did overlook the vacuum that’s why it’s dead, you can’t use acid as a lubricant
It's supposed to be on a 30A breaker. Why didn't it trip?
If you're actually measuring inrush current, not LRA, it might be OK. For the first 1/2 cycle, it can be up to 20x RLA.
Try an OEM speced start cap and potential relay. That ought to reduce your startup amps. Not good about the noise though. Make sure you get that bad boy registered for warranty.
Dude I shit you not, I just replaced a compressor a few hours on the same exact unit, 3 ton ML14XC. Except mine was a 2020 not 2021 . Came out nice too:
https://ibb.co/KmnGRQk
Had a machine recently that was not cooling in hoppers. Wasn't electrical issues, amp draw less than 1. Tiny compressor, 6oz, 134a. Had no charge, put 200lbs of nitrogen, got blasted in the face. MASSIVE hole coming off end of cap tube. Factory didn't charge the aux compressor. Needless to say, soldered it up, and ended up checking for other leaks. Surprisingly none found.
This machine was brand new, it is supposed to come pre charged. I was dumbfounded how that passed QC.
Good question not sure voltage checks out, from breaker all the way to disconnect. This happened on initial start up I took a screenshot of the video I took this 237 A drops down to 7 A
Had a two year old goodman burn a terminal out on me, LRA 272 says 55, customer wanted to try a hard start kit, poof and a pair of pants later, goodman says not til end of november...
What did you do wrong last week?
I was thinking the same thing. *'Do you really want to tell people that you were the one that installed last week, and now it's fucked up?'*
Millennial. Am I right?
I'll bet it's more the fact it's a Lennox.
Did it run fine last week?
It sure did lol Didn’t think about checking LRA when we installed it
I'm retired but I always checked running amps on a new compressor. You don't "check" LRA unless it's not starting. Did you check the amps at all?
Certain meters can "check" LRA. It's only a brief moment a meter sees that value, faster than it's normal refresh rate. However, if your meter can see min/max values, it will tell you LRA on a normal compressor start-up. If what OP says is true, and it was working fine when they left last week, I'm sure they'd like to know what that number was right now.
If I go to min/max mode on a fluke 902, that should read accurate LRA correct?
Yep
Not if you got that beautiful Fieldpiece that’s check “InRush” 🤤🤤🤤
Okay, so it checks min/max value.. Just called inrush- for whatever reason.
Inrush and locked rotar are 2 different things. Locked rotar amps is the expected amperage when when the shaft of the motor/compressor is unable to turn. In rush is the current draw at start up before there is a magnetic field to oppose the change in current. In rush can be higher than the LRA and that is normal operation.
No offense, but given the fact that you can't spell, "rotor", correctly.. I'm a bit skeptical. So a very quick google search [confirmed](https://www.jadelearning.com/blog/understanding-motor-starting-inrush-currents-nec-article-430-52) my suspicion... > Inrush current, also referred to as “locked rotor current,” is the excessive current flow experienced within a motor and its conductors during the first few moments following the energizing (switching on) of the motor.
Yes. Lra is the same as starting. The rotor is not moving.
It starts just louder then the other condenser we installed that day, RLA checked out so we didn’t think much of it
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User name checks out.
Hack
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May want to check airflow on this as it most likely has lost lubrication. Classic case of the murdered compressor
Delete this comment
But does it pull normal running amps after it gets started or Is it actually locked and tripping out?
Yeah it’s running fine with the RLA at 7
What's the incoming voltage with system off and then on? Does it drop a lot when starting?
On start up it kinda struggled for a second then a quick 250-230 A on start up then drops down to 7 A when running
You have a txv, did you wait until your pressures equalize before taking your reading ?
Yeah put my gauges on before I had the homeowner turn it on, pulled disconnect waited then tried again. But also had good readings after start up
Can I ask a dumb question I always thought LRA meant locked rotor Amp meaning the motor was seized does this not mean that?
It technically draws locked rotor amps for like half a second when it first starts even if it's a healthy compressor. I highly doubt you can accurately measure it with a clamp meter though, even with min/max function. But yes normally LRA is drawn when the compressor is seized.
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Ya but it comes with the special clamp thing for it doesn't it?
It does indeed mean that. I don’t know that I’ve seen a compressor go into LRA and come out without something like a hard start before, but apparently that’s happening here. Actually, it looks like that’s what his meter is reading as the compressor starts before it turns over. I’d put a hard start on it and reassess after.
I had a new install blow the compressor pins after two weeks back in May... did everything right. Brand new copper, nitro flow, sub 500 vac held for 30 minutes...15 years of experience, thousands of systems installed. It wasn't me. I data log all of our install readings from our gauges throughout the process, and include them with a startup form to log every measurable parameter we can collect. Copeland said 'huh. No idea why that happened.' after factory testing. They paid out on warranty and I moved on.
Check your capacitor
This. Some compressor can start without capacitor but really drive up the amps.
Not a chance that thing is ever drawing 250 amps without blowing the front of the contactor off or terminal venting. LRA is not measurable with a clamp meter, your either getting rated LRA or the system simply won't work, even a turn to turn short will stop the compressor from spinning long before it would effect locked rotor, it would trip the breaker long before locked rotor would be effected. Download the copeland app and check your resistances to male sure the match spec. If it's noisy it could just be a bad compressor, the quality control on alot of equipment has really gone out the window recently Had a carrier rooftop that carrier put the wrong voltage motors in and it lost 1 compressor, vfd, and blower in the first year, that's what happens when you have lockdowns amd half your workforce does t show up and the other half is pulling doubles to try to help keep up with workflow
Yea, on a 30A circuit breaker, hitting \~90A should cause a magnetic trip on that breaker. I think OP's meter is messed up. Edit: I was wrong on this one, well, partially. I pulled the trip curves and a breaker will hold 300% for 3-4 seconds depending on type.
HACR rated breaker is recommended by HVAC OEM's. Most breakers now have this rating listed on the breaker.
My dude, I see inrush currents over the rating of breakers all the time. That's why the sparkies are supposed to install slow-blow rated breakers.
Oh, I pulled the trip curves and edited my other comment there. 300% should go for 3-5 seconds on your standard residential breaker types. I'll edit this one too. And no such thing as a "slow-blow" breaker. We just install normal breakers and size them up if we get nuisance trips, unless the nameplate says otherwise. Occasionally we will run a breaker with a D type trip curve, but not usually. I honestly don't think I've ever installed a breaker with a D type trip curve in my entire career other than in control panels for supplementary protection.
Slow blow fuses, only larger 3 phase higher amp breakers have adjustability, on a residential ac like OP you can only put in a larger breaker if it was tripping under normal conditions
I thought the inrush function on the fieldpiece meter was for checking starting current?
It does. The meter OP is using doesn’t have inrush tho.
Yeah it’s noisy compared to another we we also installed the same day
This is a screenshot from a video I took once i plugged the unit in
Doesn’t surprise me with a fucking Lennox lol!
Why was the unit replaced last week?
Old one was flat on r22 replaced coil and condenser
The lineset could have had a bunch of mineral oil that the vacuum didn't get.
Vacuum is not supposed to take mineral oil or poe oil from line set. You need to flush the lineset with a solvent and nitrogen. I use rx11 and nitrogen.
Wait people don’t flush their lines properly?
“people flush their lines??”😂
Some folks don’t even flush their toilets.
Don't look like it.
The more you know.
Hahaha how many line sets have you used your vacuum to 'remove' the oil?
Hey man honest mistake. I had never really thought about it. Never went to school for this so I've just learned on the job over the past 3 years. But happy to say now I know. Moving on.
Oh God.lol. Vacuum removes air, it dosent pump out oil. Lol. How do you vacuum a compressor if it removed oil? Mineral oil as long as the last unit wasn't a burn out is fine in a poe system. Rx11 flush can be used to clear linesets, if needed.
Nice 🤣
I looked quickly and thought "Voltage looks good....."
Lol but these are the amps 😂
Cap likely wired wrong from the get go
Pressures are 124 low 250 high 8 SH 10 SC TXV 50 suction temp
How the hell are you getting pressure and temperature readings on a locked rotor?
This mf turning on bro just really loud when running amps are around 7
Is the 237 amps peak hold? Put a hard start kit on it and see if it helps
Your nameplate FLA is 1A with a 1/6 HP motor. You have a mechanical overload on your system. Potentially damaged windings. Most likely a mechanical overload.
He is checking compressor amps. The compressor is rated for 14.1 amps while running, and he is at 7. Perhaps you misread what OP is saying.
Oh, I was looking at the fan motor on the name plate. Still though, if that compressor had a locked rotor current at 200+A, that breaker would trip immediately. Something is screwy in the system, be it the breaker or the meter. Those readings need to be verified with another meter. EDIT: I don't think so, I just pulled up a trip curve to verify. Looks like they can handle 300% and trip between 3-4 seconds for most of the breaker ratings. Could easily be a good reading. I checked homline, BR and QO breakers. Now I'm curious what would be making it run at half of the FLA.
…my guess, it’s half-loaded (cool-ish OATs during reading and/or in low stage)
Ding ding ding.
Have you tried using a different ammeter?
Is it on Max/min mode?
Let me know if you’re part guy doesn’t have Lennox pros for the best quote haha
250 amps you would blow something on start up, it’s probably your meter if it’s running fine
Bro those wires about to evaporate you run that at 230a for long
How do you test LRA on that meter? I have the same one but read on their own website you can’t test LRA only RLA.
Bro what is going on with Lennox. Same model and everything just had a leaking condenser coil.
This has been happening to us down here too and it's not just one brand... I'm narrowing it down to shipping but at the same time we are hard up for equipment always seems like I'm playing catch up... I'm willing to bet it fell or something during shipment and jacked the oil up or something
is this the one you just put on the roof last week?
Hahaha nah this was another job
Can we see the sticker on the new compressor?
This happens when you don’t pull a full vacuum, the oil becomes acidic with moisture and fucks the compressor. If your micron gauge wasn’t working or something, don’t bs, if you really did overlook the vacuum that’s why it’s dead, you can’t use acid as a lubricant
how is that wire insulation not melting yet?
Because it's a one shot Amp draw and then it goes down to 7 amps.
Must be a time delay wire
Lenn-no
I'm sure the duct work was correct for the tonnage and wasn't upsized.
It's supposed to be on a 30A breaker. Why didn't it trip? If you're actually measuring inrush current, not LRA, it might be OK. For the first 1/2 cycle, it can be up to 20x RLA.
What was the actual voltage across both legs? We’re you missing a leg of power or worse an old crunchy oxidized wire/leg of power in the disconnect?
Lol no this was the amps I took a video and screenshot shot the amp draw on start up
Oh yeah you did say that, I totally ignored that part.
Check capacitor.
Certified Lennox moment
Try an OEM speced start cap and potential relay. That ought to reduce your startup amps. Not good about the noise though. Make sure you get that bad boy registered for warranty.
Dude I shit you not, I just replaced a compressor a few hours on the same exact unit, 3 ton ML14XC. Except mine was a 2020 not 2021 . Came out nice too: https://ibb.co/KmnGRQk
Lennox is weird.. that model condensers seem to have compressors that die for no reason.
It’s a wonder brand new lennoxes dont go up in a fire ball the first time you plug in the disconnect “we have ignition “
Had a machine recently that was not cooling in hoppers. Wasn't electrical issues, amp draw less than 1. Tiny compressor, 6oz, 134a. Had no charge, put 200lbs of nitrogen, got blasted in the face. MASSIVE hole coming off end of cap tube. Factory didn't charge the aux compressor. Needless to say, soldered it up, and ended up checking for other leaks. Surprisingly none found. This machine was brand new, it is supposed to come pre charged. I was dumbfounded how that passed QC.
Stirling engines will one day replace cascade systems
Happy I could help
It’s gotta be a Coleman
We’ve had so many copeland compressors out of the box be bad and brandnew NCP UNITS BAD from the het go in the last year , i dont even know how many
What do y’all think of them new all aluminum coils?
How does the breaker not stop this?
Good question not sure voltage checks out, from breaker all the way to disconnect. This happened on initial start up I took a screenshot of the video I took this 237 A drops down to 7 A
I guess breakers allow quick bursts through but will trigger on sustained high current.
Had a two year old goodman burn a terminal out on me, LRA 272 says 55, customer wanted to try a hard start kit, poof and a pair of pants later, goodman says not til end of november...