Author Topic: Might be my DE-5000 LCR meter damaged ?  (Read 1139 times)

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Offline ammjy

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Might be my DE-5000 LCR meter damaged ?
« on: December 11, 2019, 06:19:14 pm »
Hello,
Thanks you for your time.

I have a DE-5000 LCR Meter.

when I measure the internal inductance of RC BLDC motor, I've rotated motor almost 180 degrees with fast speed by hand to check differences.

But, after that, I realized something was wrong,,
So, I was so worried and when I have tested same condition with clamp meter, BLDC motor momentarily made 0.3 Vrms and 1 to 2 A.

Might be, because of this behavior, my DE-5000 LCR meter might be damaged ?
still my DE-5000 is working but, I worry that error things has changed.

and Attached screenshot is measured result when motor rotated by hand.
Vrms values is between 300 ~ 700mV.

I am sorry for my English.
Thanks you for reading this post :)
« Last Edit: December 11, 2019, 06:46:15 pm by ammjy »
 

Offline Caliaxy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #1 on: December 11, 2019, 06:46:02 pm »
The manual warns you to discharge the capacitors before measuring them, so yes, the voltage you induced by turning very fast the rotor might have indeed damaged the front end of the LCR meter, as you suspect. Sorry for your loss...  :(

Otherwise - wow, what a creative way to damage an LCR meter... Thanks for the heads-up!
 
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Offline DaJMasta

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #2 on: December 11, 2019, 06:46:46 pm »
It's certainly a way to do damage to it, but it still seems to be reading normally, probably no damage was done.


The way to check would be to measure some tighter tolerance/known reference parts and see if it's still reading normally.
 
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Offline ammjy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #3 on: December 11, 2019, 06:54:28 pm »
The manual warns you to discharge the capacitors before measuring them, so yes, the voltage you induced by turning very fast the rotor might have indeed damaged the front end of the LCR meter, as you suspect. Sorry for your loss...  :(

Otherwise - wow, what a creative way to damage an LCR meter... Thanks for the heads-up!

I have received it yesterdsy from post office ;) still fresh..
« Last Edit: December 11, 2019, 07:00:45 pm by ammjy »
 

Offline ammjy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #4 on: December 11, 2019, 06:58:23 pm »
It's certainly a way to do damage to it, but it still seems to be reading normally, probably no damage was done.


The way to check would be to measure some tighter tolerance/known reference parts and see if it's still reading normally.

luckily, my LCR meter seems like still reading normally RLC values and also still functional.

But, I have saw that Input part of this DE-5000 LCR meter has resistors.
and most lowest of them is 100 ohms.
than, 0.7 Vrms divide with 100 is only 0.007 mA.
it could give damage to LCR meter ?
« Last Edit: December 11, 2019, 07:04:38 pm by ammjy »
 

Offline CDaniel

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #5 on: December 11, 2019, 08:09:14 pm »
The problem could be the voltage spikes that can't be measured precisely , so don't play with inductors , or turn the motors very gently .
 

Offline e0ne199

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #6 on: December 12, 2019, 01:16:53 am »
you already know that turning the motor could produce voltage right?
can you repeat it again using multimeter and see how much voltage it will produce when you turn it 180 degree?
 
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Offline ammjy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #7 on: December 12, 2019, 02:24:39 am »
you already know that turning the motor could produce voltage right?
can you repeat it again using multimeter and see how much voltage it will produce when you turn it 180 degree?

yes,, definitely I know that rotate shaft could make energy. because it is motor. I just forgot it yesterday. because I was only focus on measure the internel inductance.

with the rotate speed and same 180degree that I remember, measured voltage is 0.227 V AC True RMS through EEVblog BM235.
through Uni-T UT210E, 0.15 V AC True RMS. (Because UT210E is slower than BM235.)

with the maximum rotate speed that I can do by hand, measured voltage is  0.86 V AC.
through Uni-T UT210E, 0.8 V AV True RMS.
« Last Edit: December 12, 2019, 03:26:43 am by ammjy »
 

Offline BravoV

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #8 on: December 12, 2019, 02:28:02 am »
To be honest, I 'm starting to worry about your scope's front end.
 
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Offline ammjy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #9 on: December 12, 2019, 03:03:00 am »
To be honest, I 'm starting to worry about your scope's front end.

Could you tell me why ?
 

Offline ammjy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #10 on: December 12, 2019, 10:43:56 am »
To be honest, I 'm starting to worry about your scope's front end.

I have did connected probe and probe ground with A and B phase of bldc motor. but, I think it is not different with measuring battery.
 

Offline Berni

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #11 on: December 12, 2019, 12:08:20 pm »
Its not about how far you turn it but how fast you turn it. Speed determines how much voltage it produces.

But unless its a really low speed high torque motor i don't think you could make en enough voltage by accidentally turning it. This voltage goes both ways. So if the max speed the motor can reach is 5000 rpm on a 12V controller then that means you need to spin it with at least 5000 rpm to get 12V out of it. That's definitely something you won't be able to do by hand.

Stepper motors can produce a lot more voltage due to having a lot of strong poles inside since those motors are designed for low speed operation.
 
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Offline ammjy

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Re: Might be my DE-5000 LCR meter damaged ?
« Reply #12 on: December 12, 2019, 01:40:08 pm »
Thanks a lot, Mr. Berini !

I think now, I don't need worry or scary anymore becuase of short moment 0.8Vrms, 1-2A.

Engineer of DER EE also said to me, if measured value is close with known values during measure RLC, DE-5000 is still working.


 


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