PPP - Voltage Accuracy

[Still-One]

Have any of you checked the accuracy of your PPP's voltage readouts?

I have been curious since I installed my units about the accuracy of the readout for uncorrected voltage input. You may remember that my units are connected to separate 20 amps circuits. The uncorrected voltage during the day usually show about 122-3 on one unit and 120-1 on the other. In the evening (I assume when local demand goes down) this can jump 124. What was curious is that the APC unit on my sources and a second APC unit on some equipment in another room never showed these high readings.

Today I went out an purchased a new voltage meter and checked the plugs where the PPP's and the APC units are plugged in. The muti-meter indicates that the PPP's are showing the voltage too high. One PPP showed 122 and the multi-meter showed 119.8. The other showed 120 and it was again about 119.8. I then checked the plug where the APC S-15 is connected. The APC unit showed 118, the voltage meter showed 118.2.

I am going to wait until later this evening when the PPP's input usually jump and re-check the numbers.

The PPP's do show the corrected numbers to be right at 120.

Jim

[j3brow]

Interesting findings. I have not checked mine. My input ranges from 122 - 124 according to the PPP. are the voltage multimeters (1) cheap (2) easy to use?? If so, I would be willing to give em a whirl to double check my readouts. How would one know that the purchaced multimeter is accurately calibrated?

[hkval]

If possible, with your new voltage meter, check the voltage coming out of the PPP several times during the day because that would be the most important reading.

[Still-One]

I am not sure of the accuracy of the voltage meter, but it does read very close to what the APC units indicate they are seeing from the wall.

Howard, I will try the meter into the PPP outlets on the back to see if it shows the corrected voltage coming out at 120.

[jdandy]

Jim.......This is the link to the PPP service manual. On page 14 is the procedure for Display Calibration. With this procedure you can calibrate the display for both input and output voltages.

I have not done this yet, but I plan to do the display calibration for input and output voltage on all three of my PPP's.

Hope this helps you. http://www.psaudio.com/uploads/files...01-X-DSM-A.pdf

[Still-One]

Originally Posted by jdandy

Jim.......This is the link to the PPP service manual. On page 14 is the procedure for Display Calibration. With this procedure you can calibrate the display for both input and output voltages.

I have not done this yet, but I plan to do the display calibration for input and output voltage on all three of my PPP's.

Hope this helps you. http://www.psaudio.com/uploads/files...01-X-DSM-A.pdf

Dan

Thanks for the information.

Is this what you would do to calibrate the incoming display? Take several reading using the multi-meter from the wall socket, then adjust the display as close as yo can to that number?

To calibrate the corrected voltage, take readings from several of the plugs on the back of the PPP and adjust the corrected to voltage to those numbers?
jim

[jdandy]

Jim.......With your meter, take your reference voltage reading from the same receptacle that you will plug the PPP into during the calibration process. It doesn't have to be the outlet you use in your setup. Plug the PPP into this outlet, and adjust the Input Voltage display to match the meter's reading.

Next, plug your meter into any receptacle on the PPP (they are all attached to the same buss bar). Using the small potentiometer on the bottom side of the PPP, adjust it until your meter reads 120 volts output at the receptacle on the back of the PPP. Now, perform the output voltage display calibration to read 120 volts. That should do it.

[Still-One]

Originally Posted by jdandy

Jim.......With your meter, take your reference voltage reading from the same receptacle that you will plug the PPP into during the calibration process. It doesn't have to be the outlet your use in you setup. Plug the PPP into this outlet, and adjust the Input Voltage display to match the meter's reading.

Next, plug your meter into any receptacle on the PPP (they are all attached to the same buss bar). Using the small potentiometer on the bottom side of the PPP, adjust it until your meter reads 120 volts output at the receptacle on the back of the PPP. Now, perform the output voltage display calibration to read 120 volts. That should do it.

Got it on the first part.

Why wouldn't I adjust the output voltage to match the multi-meter before I adjust the potentiometer on the bottom. Don't you only adjust that if it will not correct it to 120?

[jdandy]

Jim.......The pot on the bottom of the PPP adjusts the actual output voltage. By adjusting this to exactly 120 volts output while reading it with your meter, when you begin the output calibration procedure you will then be calibrating the display to match the actual output voltage. The display, and the output are two seperate things.

[Still-One]

Originally Posted by jdandy

Jim.......The pot on the bottom of the PPP adjusts the actual output voltage. By adjusting this to exactly 120 volts output while reading it with your meter, when you begin the output calibration procedure you will then be calibrating the display to match the actual output voltage. The display, and the output are two seperate things.

Dan

Thanks. I now have the uncorrected input voltage from the wall plug as read by the multi-meter matching the display input , and the corrected display output voltage matching the multi-matchmeter reading from the PPP rear plugs.

Thanks, Jim