Chinese motor question

This is the product-
I contacted Vevor technical support
Oh boy vevor, good luck. I am dealing with them right now. Have their crane scale and a bunch of lines on the LCD display stopped working. They actually told me to " find a local technician" to fix it and they would reimburse me. I said no way, then their next offer was $60 (it's $200).....ummm what part of "everything we sell has a 12 month warranty" am I not understanding??
 

jrjr2u

Member
Location
Central NY
Occupation
retired
Oh boy vevor, good luck. I am dealing with them right now. Have their crane scale and a bunch of lines on the LCD display stopped working. They actually told me to " find a local technician" to fix it and they would reimburse me. I said no way, then their next offer was $60 (it's $200).....ummm what part of "everything we sell has a 12 month warranty" am I not understanding??
Luckily for me I have nearly $0 invested. I did purchase a 240 outlet but that's it so far. I had the plug end and some 16ga already. That part is done. Now if it would just warm up a bit more.... middle of the week they say. Might tough it out though. 40's isn't too bad.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
The volts to hertz ratio for 400V 50Hz is the same as 480V 60Hz -8- so your motor would run on either power system with no changes to the motor. The only thing I can think of that he would have changed is the configuration of leads to accommodate a supply Voltage of 240V or 480V.
Ahh interesting so if the ratio stays the same then the OP's motor would perform the same as at 50hz? He'd have to run it off 265V somehow.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Ahh interesting so if the ratio stays the same then the OP's motor would perform the same as at 50hz? He'd have to run it off 265V somehow.
No. You were asking about a 400V motor. In his case he has a motor rated for the applied voltage. A 220V 50Hz motor can run on 60Hz it will just run faster. It doesn't always work the other way ie. a 60Hz motor may not like 50Hz so well.
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
No. You were asking about a 400V motor. In his case he has a motor rated for the applied voltage. A 220V 50Hz motor can run on 60Hz it will just run faster. It doesn't always work the other way ie. a 60Hz motor may not like 50Hz so well.
I'm inclined to agree with you.
 

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Oh boy vevor, good luck. I am dealing with them right now. Have their crane scale and a bunch of lines on the LCD display stopped working. They actually told me to " find a local technician" to fix it and they would reimburse me. I said no way, then their next offer was $60 (it's $200).....ummm what part of "everything we sell has a 12 month warranty" am I not understanding??
It’s not just the Chinese, I hooked up a brand new Italian made CNC machine a couple of months ago. Worked about a week, then the X axis sensor quit working. The company that sold it to them swore up and down it was a shorted sensor wire, that someone had stepped on the wire trolley in the back of the machine. They would not send anyone out to look at it. They wanted an electrician to check the wiring, but absolutely do not remove the sensor. Sensor had two outputs, both were showing contacts closed regardless of position. Pulled the wires off the sensor, wiring checked perfect. A month later, they decided to finally send a new sensor. Totally wrong sensor! But since I was able to see how the sensor worked, I figured out what was wrong with the old one. They had an adjustment screw on both sets of contacts that fine tuned when they make and break. The block that pushed the plungers down when the machine reached its end point, was adjusted too tight, and wore grooves into the sensor damaging it. Re-adjusted the screws on the sensor, and it started working again. They were flying in a tech from Germany to look at it, and since they weren’t reimbursing the owners for my time, I changed it back. The owner said they didn’t even attempt to troubleshoot it, they just replaced the sensor with the correct one they brought with them. After several months, they finally was able to use the new machine again.
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
While probably not a practical way to use it when conveying material, I'd block the suction side with an ammeter inline. "No" airflow == "No" load. See what the run current is, and open the inlet allowing more flow. You might be able to use a pair of concentric or eccentric reducers and find an effective operating point.
 

jrjr2u

Member
Location
Central NY
Occupation
retired
While probably not a practical way to use it when conveying material, I'd block the suction side with an ammeter inline. "No" airflow == "No" load. See what the run current is, and open the inlet allowing more flow. You might be able to use a pair of concentric or eccentric reducers and find an effective operating point.
Interesting.... will keep that in mind!
 

kwired

Electron manager
Location
NE Nebraska
Ahh interesting so if the ratio stays the same then the OP's motor would perform the same as at 50hz? He'd have to run it off 265V somehow.
It still going to run about 17-18% faster because of the frequency, which will cause the centrifugal fan to demand more power at that speed (if nothing is changed there). Now if this motor were designed/intended to be run at that frequency then it might be ok, but it will not give same performance at both frequencies.

VFD's do vary voltage as well as frequency and will maintain V/F ratio no matter what speed they are running at, it is part of the basics of how and why they will work on a given motor. They can be tweaked to vary that ratio a little while accelerating or decelerating to get some torque boost but you can't leave it out of the base V/F ratio range for long or it is hard on the motor windings.

If you are running a 60 Hz 460 volt motor at 30Hz, the drive output will be ~230 volts, full load HP at that speed is half the HP it is at full speed, if it is running at this halved full load current will be same as nameplate full load current. V x A will be half the nameplate V x A - half the speed can deliver half the power, slight variances is because of efficiency aspects but will be pretty close to half the power as at full speed. Where it gets more complex is with variable torque loads like centrifugal fans and pumps, constant torque loads are mostly linear as speed changes.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
It still going to run about 17-18% faster because of the frequency,
Theoretically if the OP had some way to run his motor at 265 Volts (using a buck/boost or variac) it would perform the same right?
Just like runing a 400V 50 hz motor at 480V 60hz?
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Theoretically if the OP had some way to run his motor at 265 Volts (using a buck/boost or variac) it would perform the same right?
Just like runing a 400V 50 hz motor at 480V 60hz?
It would still run faster because an AC motor's speed is determined by frequency also, you would be pushing the limits of the motor giving it that much voltage using a normal motor starter. There is some crazy stuff you can do with a VFD where you set the motor up for 240V and somehow program the voltage to run up as high as 480V but I have never seen it in real life.
 

kwired

Electron manager
Location
NE Nebraska
It would still run faster because an AC motor's speed is determined by frequency also, you would be pushing the limits of the motor giving it that much voltage using a normal motor starter. There is some crazy stuff you can do with a VFD where you set the motor up for 240V and somehow program the voltage to run up as high as 480V but I have never seen it in real life.
For the most part to do this with a typical general purpose motor you also would need to run it at 120 Hz and would double the speed in the process. It still is capable of delivering same ft/lbs per second it will just be doing it at a higher speed, but if you were driving a centrifugal fan or pump the load imposed on the impeller increases exponentially as speed increases, presuming infinite carrying capacity of the conveying ducts or piping.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
For the most part to do this with a typical general purpose motor you also would need to run it at 120 Hz and would double the speed in the process. It still is capable of delivering same ft/lbs per second it will just be doing it at a higher speed, but if you were driving a centrifugal fan or pump the load imposed on the impeller increases exponentially as speed increases, presuming infinite carrying capacity of the conveying ducts or piping.
More properly, it increases as the cube of the speed.
Some people these days are using "exponential" when referring to any rapid growth, anything greater than a linear function.
 

Besoeker3

Senior Member
Location
UK
Occupation
Retired Electrical Engineer
Good grief !! Is this rumbling on for such a piddling little little motor ! And from the wrong country..........seems a bit daft.
 
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Some people are just plain Bad at Math.

What many folks don't comprehend is that slow, steady growth -- even 0.000001% per year -- is also exponential growth.
Well here is the first definition from the dictionary:


ex·po·nen·tial·ly
/ˌekspəˈnen(t)SHəlē/
adverb
1.
(with reference to an increase) more and more rapidly.
"our business has been growing exponentially"

I am a magna cum laude math major and I use that "simple" definition all the time.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Good grief !! Is this rumbling on for such a piddling little little motor ! And from the wrong country..........seems a bit daft.
Just imagine the UK is one of 5 countries on earth to use the 230V 50hz system and the rest of world standardized on the US 60 hz system.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Well here is the first definition from the dictionary:


ex·po·nen·tial·ly
/ˌekspəˈnen(t)SHəlē/
adverb
1.
(with reference to an increase) more and more rapidly.
"our business has been growing exponentially"

I am a magna cum laude math major and I use that "simple" definition all the time.

Yeah, no one seems to talk about their business decreasing exponentially, or oscillating up and down like expressions with complex exponentials can do.

One thing that annoys me instead is people using "turbo" for all sorts of things that have nothing to do with turbines. But if some expression gets used enough it will eventually be put into dictionaries.
 
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