Calculation of peak voltage

Ganesh karri · Oct 16, 2014

1. i am getting voltage feedback from welding power source of (0-10VDC) which includes peak and base voltage for time duration of 0.2 sec
i.e i am getting voltage feedback of (5vdc 0.2sec time delay 4vdc & 5.2 vdc 0.2 sec time delay 4.2vdc.etc etc etc continuously ) so 5vdc first value is peak voltage and 4vdc is base voltage) ,
this feedback voltage i am connecting to plc and in plc program i want to display only peak voltage by neglecting base voltages (i. e in HMI scree i must only display peak voltage ) is it possible to record data with respect to 0.2sec speed .?? can anyone help in programming (micrologics 1500 AB plc)

Ganesh karri · Oct 16, 2014

Any Answers ???

Badger · Oct 16, 2014

Be patient, this is a free site people come here to help in their own time and do not like to be jostled.

beethoven_ii · Oct 16, 2014

Your question isn't particularly clear but to record a peak value of anything is pretty straight forward. Compare the value you are monitoring (Value A) with another register of the same data type (Value B) and whenever Value A is greater than Value B move Value A into Value B. Or have I misunderstood your question?

Ganesh karri · Oct 16, 2014

Hai Beethoven , thanks for your reply .
but
1.how to separate peak and base voltages with one continuous analog signal (0-10VDC) with fast change of 0.2sec/0.15 sec

beethoven_ii · Oct 16, 2014

Your peak voltage is always higher than your base voltage and you say you only want to display the peak value so why do you need to separate the 2?

Ganesh karri · Oct 16, 2014

consider this is analog signal , with in this signal we have peak and base voltages and these voltages are keep on varying based upon ARC voltage/length (5- 0.2sec - 4 & 5.2-0.2sec -4.1 & 6-0.2 sec -5 & 7-0.2sec -6.1 etc etc continuously ) like pulses...
Note:As u said if i separate Value A and Value B ..my job is done no need of comparing values ..i can directly display values A ,,But i need to monitor peak(value A).

Badger · Oct 16, 2014

What PLC do you have?

Ganesh karri · Oct 16, 2014

Allen Bradley micrologics 1500

Badger · Oct 16, 2014

Have you tried to capture the data yourself or monitored it in the PLC program. I am not a AB man myself but there is a wealth of knowledge on here that will help you but they will want you to show what you have done yourself then they will guide you through it.

TConnolly · Oct 16, 2014

I think I'd record samples at a .1 second rate and remember three or four
samples. The sample with the highest value is the peak.

See attached example. This example stores a sample every 0.1 seconds in a four integer stack. The voltage is scaled to millivolts. First thing it does is copy the stack down one, so N10:1 is copied down to N10:0, then N10:2 copies down to N10:1, N10:3 copies down to N10:2. Then the newest reading is stored at N10:3. That way your PLC remembers the last four readings. (The COPy has to move data down, it can't move it up or it will just fill the whole stack with N10:0.) Then the program searches N10:0 through N10:3 for the largest value. After if finds the largest value it divides it by 10 and stores it at F8:0

Ganesh karri · Oct 16, 2014

Thanks TCONNOLLY ...good idea ...let me try real time

Ganesh karri · Oct 16, 2014

I have one more idea .. ( this is related to TIG Welding machine -Fronius )
this analog signal is for voltage feedback and i will take current feedback by connecting CT from one terminal of the cable (+/-) the feedback from CT is o-10vdc with respect to 0-1000vdc pulse signals , this is the exact peak & base current with out any disturbances ...
by using this analog i can do any thing better ...to read only peak voltages ...... THIS IS FOR AUTOMATIC VOLTAGE CONTROL ...

shooter · Oct 17, 2014

So you say it is jumping between peak and base every 0.2 seconds?
so the wave is square.
just take samples anytime.
If sample is below average it is base if above it is peak.
have a moving average of 10 samples,

another way is to look at it like asynchronous communication, if you see a flank wait 0.1 second and take a sample, wait till next flank and wait again. (this will need a fast PLC.

Ganesh karri · Oct 17, 2014

Good one

Calculation of peak voltage

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