Previous in Forum: Lead Acid Battery Usage   Next in Forum: Heater
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
19 comments
Rate Comments: Nested
Anonymous Poster

Output Voltage of AC to DC Converter

10/16/2010 9:04 AM

The input voltage of ac/dc converter is 405V, And the Output voltage should be 572.67V(1.414 * 405V). But instead it is showing 620v. Could u please explain what moght be the reason? Will it happen becaues of Noice or Harmonics?
Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
JRaef
Guru
United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
Posts: 4665
Good Answers: 804
#1

Re: Output Voltage of AC to DC Converter

10/16/2010 11:01 AM

Smoothing capacitors. It is probably an unregulated power supply and you are probably measuring that output with no load. Put a rated load on it and then measure it again.

__________________
 ** All I every really wanted to be, was... A LUMBERJACK!.**
Reply
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#11
In reply to #1

Re: Output Voltage of AC to DC Converter

10/19/2010 3:12 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply
shiva_pvv@yahoo.co.in
Active Contributor

Join Date: Jul 2008
Posts: 11
#2

Re: Output Voltage of AC to DC Converter

10/16/2010 11:22 AM

in this i want to know why input is to multiply with 1.35 ,to get dc voltage pls send if u know dis..........
Reply
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#17
In reply to #2

Re: Output Voltage of AC to DC Converter

10/19/2010 3:22 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#3

Re: Output Voltage of AC to DC Converter

10/16/2010 11:37 AM

It sounds like your AC to DC converter contains an under loaded transformer, but without a schematic this is complete speculation. The root of your problem could be from an error in measurement, clever fly-back implementation, a wave length reflection or even an additional voltage source that you don't know about. I do realize that you don't understand what is happening here so you cannot accurately describe your circuit. If you could describe it then you would likely understand what was happening and would not be asking for our help. If you do not have a formal schematic of the circuit, I recommend that you sketch one for yourself with nodal voltage measurements included. Next do a nodal analysis utilizing Kirchoff's laws.

Your input voltage of 405V is a lethal voltage. Be very careful.

If you do not know how to make a schematic, perform a nodal analysis, or understand Kirchoff's laws then you should put the meter down.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Reply
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#6
In reply to #3

Re: Output Voltage of AC to DC Converter

10/16/2010 5:19 PM

One thing I forgot to mention, you should also be careful what your meter is actually telling you. All meters should give RMS voltages in the AC setting for a pure sine wave, but unless the meter has a True RMS feature any other wave form could give you a misleading number.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Reply
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#10
In reply to #3

Re: Output Voltage of AC to DC Converter

10/19/2010 3:11 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#18
In reply to #10

Re: Output Voltage of AC to DC Converter

10/19/2010 10:04 AM

First, you do not have to repeat yourself with every reply. Repeating yourself in this fashion implies incompetence.

Second, this appears to be a wiring distribution diagram and not a circuit schematic. At least that's what I'm guessing from the block pattern. I cannot read the text anywhere in this diagram. What is clear to me from the diagram you've posted is that you do not understand the idea of nodal analysis or Kirchoff's laws.

Please, put the meter down and defer to a qualified electrical technician, electrician, or electrical engineer at your facility. You are working with lethal voltages that probably have plenty of available current. Working on a system with this much available energy without a sound understanding of electric circuits puts everyone around you at risk.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Reply
wareagle
Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#4

Re: Output Voltage of AC to DC Converter

10/16/2010 12:11 PM

Quote Shiva "in this i want to know why input is to multiply with 1.35 ,to get dc voltage pls send if u know dis.........."

Quote from Wiki

Power and root mean square

The relationship between voltage and the power delivered is

where R represents a load resistance.

Rather than using instantaneous power, p(t), it is more practical to use a time averaged power (where the averaging is performed over any integer number of cycles). Therefore, AC voltage is often expressed as a root mean square (RMS) value, written as Vrms, because

For a sinusoidal voltage:

The factor is called the crest factor, which varies for different waveforms.

[edit] Example

To illustrate these concepts, consider a 230 V AC mains supply used in many countries around the world. It is so called because its root mean square value is 230 V. This means that the time-averaged power delivered is equivalent to the power delivered by a DC voltage of 230 V. To determine the peak voltage (amplitude), we can rearrange the above equation to:

For our 230 V AC, the peak voltage Vpeak is therefore , which is about 325 V. The peak-to-peak value of the 230 V AC is double that, at about 650 V.

Note that some countries use a frequency of 50 Hz, while others use a frequency of 60 Hz. The calculation to convert from RMS voltage to peak voltage is independent of the frequency
Reply Score 1 for Good Answer
Go to Next "Almost" Good Answer
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#12
In reply to #4

Re: Output Voltage of AC to DC Converter

10/19/2010 3:14 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
2
msamad
Guru

Join Date: Feb 2009
Location: Houston, USA
Posts: 946
Good Answers: 244
#5

Re: Output Voltage of AC to DC Converter

10/16/2010 2:55 PM

For true sine wave, the ratio of the rms value (AC measured value) to the average value (DC measured value) is 1.11 (= π/2√2). This ratio is called form factor.

So, DC voltage = (AC voltage) / 1.11

If 405 VAC, single phase is converted to DC with full wave rectifier, the output should be approximately 405/1.11 = 364 V.

If it is a single phase half wave rectifier, the DC voltage will be half of it.

If it is a three phase full wave rectifier, the DC voltage will be 3 times (the sum of the average values of each of the phase).

However, there are many factors that may affect the output DC voltage, such as bridge full wave, center-tap full wave, half wave, internal transformer ratio (in most cases, a transformer is used within the rectifier), voltage regulation, ripple factor, Harmonics, filtering system etc.

I am not sure yours one is three phase half wave rectifier. In this case, the expected DC voltage is (405/1.11) x (1/2) x 3 = 547 V

Note: I assumed you measured the AC and DC voltage using the AC and DC voltmeter. If you used AC meter to measure the DC, you got the wrong value.

See these:

http://en.wikipedia.org/wiki/Form_factor_(electronics)

http://en.wikipedia.org/wiki/Rectifier

- MS

__________________
 "All my technical advices in this forum must be consulted with and approved by a local registered professional engineer before implementation" - Mohammed Samad (Linkedin Profile: http://www.linkedin.com/in/msamad)
Reply Good Answer (Score 2)
Go to Next Good Answer
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#13
In reply to #5

Re: Output Voltage of AC to DC Converter

10/19/2010 3:16 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
Dub
Commentator
Hobbies - Musician - New Member Hobbies - DIY Welding - New Member Hobbies - Fishing - New Member Engineering Fields - Acoustical Engineering - New Member Engineering Fields - Electrical Engineering - New Member United Kingdom - Member - New Member

Join Date: Oct 2010
Posts: 58
Good Answers: 1
#7

Re: Output Voltage of AC to DC Converter

10/17/2010 9:34 AM

I have to agree with 1 and 3 you are either measuring open circuit on an unregulated supply, using the incorrect meter setting, or an un calibrated / bad quality meter. you only need a tolerance of ten percent to take your reading to 620v and i have seen some meters as bad as 35% tolerance. check these things before you possibly go any further.

Good Health Dub.

__________________
 If you do not have you own philosophy you cannot amend it.
Reply
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#14
In reply to #7

Re: Output Voltage of AC to DC Converter

10/19/2010 3:18 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
2
marcot
Guru
Canada - Member - Specialized in power electronics

Join Date: Feb 2008
Location: Montreal, Canada.
Posts: 1372
Good Answers: 80
#8

Re: Output Voltage of AC to DC Converter

10/17/2010 2:18 PM

As many have already stated, this higher than expected voltage will go away with a load.

The first cause is that switching the power in the discharged (or partially charged) capacitor will create an inrush current followed by a voltage overshoot. This comes from the resonance of the source inductance and the capacitance and is "peak detected" by the diodes. Without a load, the discharge time can be long.

Later, if you still have the higher voltage, the probable cause is the boosting effect again caused by the source inductance, the diode rectifier, and the capacitor. The stray capacitance between the DC section and the source and certainly participate. This effect is not very strong. But without load, the capacitor voltage can rise significantly.

Finally, if you have a load that draw current in pulses with very little energy consumption, the DC bus can be boosted significantly.

Good luck and be careful. High voltages with high energy are dangerous. Capacitors explodes. Wear glasses...

__________________
 Experienced is earned, common sense is taught, both are rare essentials of life.
Reply Good Answer (Score 2)
No more Good Answers. Go to first "Almost" Good Answer
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#15
In reply to #8

Re: Output Voltage of AC to DC Converter

10/19/2010 3:19 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
marcot
Guru
Canada - Member - Specialized in power electronics

Join Date: Feb 2008
Location: Montreal, Canada.
Posts: 1372
Good Answers: 80
#19
In reply to #15

Re: Output Voltage of AC to DC Converter

10/19/2010 10:14 AM

Measure the current flowing into the various grounding conductors and even the metal supports for electrical components. It looks like you have a large ground leak or some sort of large imbalance. Check for shorts to ground. Be careful, parts that are supposed to be grounded might have potential. During the verification, double the machine grounding circuit just in case.

Good luck

__________________
 Experienced is earned, common sense is taught, both are rare essentials of life.
Reply Score 1 for Good Answer
No more "Almost" Good Answers.
kvsubramanyam
Guru

Join Date: Apr 2007
Location: Hyderabad, India
Posts: 596
Good Answers: 12
#9

Re: Output Voltage of AC to DC Converter

10/18/2010 12:06 AM

Put less than 3% load and measure again, you will get correct DC voltage!

__________________
 Subramanyam
Reply
Nithin111
Member

Join Date: Oct 2010
Posts: 8
#16
In reply to #9

Re: Output Voltage of AC to DC Converter

10/19/2010 3:21 AM

Find the attached Power Circuit diagrem of the machine. The input voltage of the Semo Drive is 405VAC and the Output Voltage is 620V. When we are giving power to the machine that time noice is coming. Also there is a very heigh magnetic flux appears near the machine. When the Drives are geting enabled that time noice also become very high. Please explain what type of preventive measure we have to take for avoiding this problems.
Reply Score 1 for Off Topic
Reply to Forum Thread
Have a Different Question?
19 comments

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Dub (1); JRaef (1); kvsubramanyam (1); marcot (2); msamad (1); Nithin111 (8); redfred (3); shiva_pvv@yahoo.co.in (1); wareagle (1)

Previous in Forum: Lead Acid Battery Usage   Next in Forum: Heater

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (82 right now)
Show Members
Advertisement