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sharath4
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Voltage Measurement

07/02/2012 1:57 AM


VFD- Variable Frequency Drive

V- Voltmeter

M- Motor (Brushless DC)

Voltmeter measuring voltage = voltage supplied to the motor - Voltage coming back from the motor (back emf) - Voltage drop in the motor.

Is this correct?

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Joshi
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#1

Re: Voltage measurement

07/02/2012 2:38 AM

No.
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sharath4
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#4
In reply to #1

Re: Voltage measurement

07/02/2012 4:56 AM

Then what will be the reading of voltmeter?

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PWSlack
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#8
In reply to #4

Re: Voltage measurement

07/02/2012 9:48 AM

The voltage applied to the motor.

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Tornado
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#2

Re: Voltage measurement

07/02/2012 2:53 AM

And what is a VFD doing on a DC motor?

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sharath4
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#5
In reply to #2

Re: Voltage measurement

07/02/2012 4:57 AM

Its not DC, its brushless DC, VFD is used for electronic commutation

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PWSlack
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#3

Re: Voltage measurement

07/02/2012 3:19 AM

No (plus #2↑).

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sharath4
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#6
In reply to #3

Re: Voltage measurement

07/02/2012 4:57 AM

Why??

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PWSlack
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#7
In reply to #6

Re: Voltage measurement

07/02/2012 6:58 AM

If it were a PWM controller on a DC motor, then fine. If it were a VSD controller on an AC motor, then fine. One cannot mix-and-match; it's NBG.

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redfred
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#9

Re: Voltage Measurement

07/02/2012 11:29 AM

You need to review your electric motor fundamentals. All electromagnetic motors work by magnets attracting and repelling each other. In your review of motor fundamentals you will see that a variable frequency drive (VFD) generates an AC signal and not a DC signal.

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sharath4
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#10
In reply to #9

Re: Voltage Measurement

07/03/2012 1:25 AM

Yeah you are right..

It should be an AC motor, then what is the voltmeter measurement??

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redfred
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#11
In reply to #10

Re: Voltage Measurement

07/03/2012 9:27 AM

What do you want? If you want a numeric value, I'll give you 42. If you want an understanding of what the motor is doing by just measuring the voltage across the stator windings then you cannot have that. Why? Well that's because you do not provide enough information to discern at all what is happening. You really need to review your electric motor fundamentals.

Without a basic understanding of electricity, kinematics and how an AC induction motor works a correct answer will likely not be understood by anyone.

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sharath4
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#12
In reply to #11

Re: Voltage Measurement

07/03/2012 10:53 AM

Well, i dont want 42 for now okay. I think u dont need numbers to answer this.

i think u didnt see the original post correctly. see my 1st post

and you are not able to catch the question.

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Doorman
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#13
In reply to #12

Re: Voltage Measurement

07/03/2012 11:11 AM

The reading of the voltmeter will be null.

In your schematic there is a motor, a VFD, and a meter.

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redfred
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#14
In reply to #12

Re: Voltage Measurement

07/03/2012 11:18 AM

You are absolutely correct, I am not able to catch your question from the way you've written it. This is why I asked you, what do you want? Your original question of this thread has a glaring mismatch of hardware choices. Your original question is wrong. Please rephrase your question.

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sharath4
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#15
In reply to #14

Re: Voltage Measurement

07/04/2012 12:28 AM

V- Voltmeter

M- AC motor

VFD - Variable Frequency Drive

In operating condition, will voltmeter read the value only applied to the motor from drive or what?

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Tornado
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#16
In reply to #15

Re: Voltage Measurement

07/04/2012 12:33 AM

Yes, it will read the voltage applied to the motor.

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redfred
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#17
In reply to #16

Re: Voltage Measurement

07/04/2012 8:30 AM

Yes, I'll buy that.

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Doorman (1); Joshi (1); PWSlack (3); redfred (4); sharath4 (6); Tornado (2)

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