Power Plant Premier - THD and protection mode advice please


I have 2 PPP recently purchased used from different sellers and different countrys. Both advertised as functioning 100% and from a general point of view they seem OK.

My problem is that BOTH are exhibiting the same behaviour simultaneosly and i dont know how to fix this.

They both switch into protection mode (simultaneosly) at random times of the day for a few minutes and then back to normal. When this happens i managed to notice that THD rises to 6% - 7% when its normal value fluctuates between 2.5% - 3.5%.

It seems the PPP is switching to direct wall power when the THD rises above 6%. Is this normal ?

Also, i notice a toroidal mechanical hum from within the PPP and also from speakers when this is happening. As if the AC noise travels through the PPP and through my amplifier into the speakers, when THD is high and emmits noise.

I read some users reporting using the PPP in 5%-6% input THD normal values and no problems.

The values of THD i am referring to are INPUT.

The OUTPUT THD values usually are at 0.7% when in normal AC ( with 3% THD input).

Given the two PowerPlants are acting exactly the same I conclude they are behaving normally.

Increased incoming THD is often accompanied by decreased voltage. It may be the combination which is triggering bypass mode.

So i should make note of what is happening during these “bypass modes”, naming the voltage input and output plus THD input and output.

If only i could “predict” when this happens :slight_smile: I will try and check it out as soons as it happens.

Thank you

One thing is bugging me…

What can be causing the PPP to read 6% or 7% THD input, for a few seconds…and then back to 3% ?

The rise only occurs for 2-3 seconds and then reduces again…when clicking occurs.

The fact that BOTH units do the same, leads me to exclude malfunctioning…

I should note that NOTHING is being connected or disconnected or turned on/off in my house during this behaviour. Plus it usually happens at late hours in the evening (between 8pm - 12pm)

I cannot say the same for my neighbours though (apartment building)

Voltage and THD can change significantly over a short period of time, such as when a large motor starts.

Caught the abnormal THD values again. I can say that

  • input voltage is steady 229V
  • output voltage is steady 234V
  • input THD was at 4% and rised to 6.7% for a few seconds then back to 4%

During this rise to 6.7% the PPP cliked into protection mode and then back to normal mode.
No other signs were evident.

Question: why is my PPP clicking to protection with a small rise of THD for a few seconds?
What can i do to prevent this?

You say the input voltage is “a steady 229V”. Is that as reported by the PPP, or as measured with a voltmeter at the wall?

Measured at the PPP display.
As i said, this behaviour only occurs for a few seconds and every other night.
Some nights it does not happen and other nights it can happen 3 or 4 times.

I can try to plug my multimeter to the wall and see if the input voltage is indeed not changing during this…but its a matter of luck.

I didn’t mean for you to catch the wall output at the crucial time; just to compare the real voltage with what the PPP is showing. It’s a far shot, but maybe the PPP’s should be re-calibrated.

Oh OK.
I remember i tested and compared this once, because each PPP show a litle different values.
At the time , both were off a small amount, not enough for me to concern with calibration .
I believe it was off like 2 or 3 volts, but who knows if its my multimeter that is off and not the PPP ?
My PPP nº1 shows 229V, when my PPP nº2 shows 231V inputs.

It is highly unlikely your multimeter is off by that much.

I went ahead and did the calibration procedure as mentioned here in the forum and the service manual for the PPP.

Both units are now calibrated for 230V output.
Yesterday input was showing 238V both in PPP display and off the wall with the multimeter.

THD was 2.1% input and 0.5% output.

When i was installing and connecting the PPP’s again, i noticed the input THD rising again.
This time from 2% to 4% for a few seconds and back again. This occurred for a few minutes and then stopped.
The rise to 4% was not enough to send the PPP into protection mode , BUT :

  • Whenever the THD was rising, the PPP emmits a mechanical transformer NOISE (like a loud rattle) .
  • In the past i noticed this “rattle” or “hum” from the transformers, not only from the PPP but also from my Power Amplifier Transformers !! This rattle is clearly audible from listening position 3 meters away.

So i am concluding my AC mains send out QUITE A BIG NOISE DISTORTION from time to time, that not only send my PPP into protection, but also makes every power transformer (power amp) oscillate and make audible noise.

QUestion :

  • Should i go and try to find the cause of this AC distortion? Can this be some electrical device inside my house ?
  • Can this be caused outside my house, and as such, no control whatsoever can be done
  • Can i install some kind of filtering , behind my PPP’s to filter this out ?


Anyone wants to help here? Suggestions?

Saf, personally I think if all of your household appliances work fine coupled directly from the wall output, then so should your PPP’s. In fact, even more so as it is designed to improve & protect an imperfect power source to begin with.
I think your PPP’s will have to go in to PSA for servicing. Sorry I know this does not sound very helpful.
If PSA offer you a killer deal on a P5, P10 or P20 upgrade and you can afford it, grab it. Also remember that PSA is likely to receive a number of 2nd hand P5’s and P10’s in soon so this route may be more affordable than what you think. The outgoing P5/P10 is an order of magnitude improved over the PPP and much more capable at handling the type of anomalies you describe.

Edit: Sorry, I see you’re obviously not close to PSA [220/230V] so that makes the trade-up route difficult or impossible. What country are you in? It would be best to work thru’ your local distributor and/or dealer.

Well , i live in Portugal so i believe we get no “special discounts” from PS Audio here.
Also, sending both my PPP in for repair when BOTH are exhibiting the same behaviour seems odd.
I am more leaned torwards some kind of correction in my AC feed that seems to be behavouring oddly time to time.

I agree; it is unlikely both units have some sort of identical fault.

IMHO that’s the regen’s job. Truly hope you get sorted somehow!.
BTW you should also get into contact with PSA tecnichal - email them the serial numbers of your units.

I would also recommend you contact PS Audio on this. There have been some units (old version Power Plant Premiers) in the distant past that have had bad parts in them. I purchased a demo PPP from a dealer SIX years ago, and I had similar problems with it and ended up returning it, replacing it with the new generation P5. I had then (and now) a very stable power feed.


How can i get in touch with PSA technical ?
I was hoping someone from PSA would chime in here.

I’d just give them a call in Colorado and request someone in technical support.