My monitor's power supply creates spikes on the outlet, will it burn my house?

[sblantipodi]

Guys I'm a little worried about my monitor's power supply.

I have an Acer X32FP, before I got one that met my accuracy requirements I tried several units and they all had the same problem

What you see in this screenshot is my home automation system recording the loads on the electrical outlet.

On that electrical outlet there is only the monitor's power supply now and nothing else.
The power supply is also disconnected from the monitor.

How is it possible that several times in an hour it has an absorption of around 80W if it has no peripherals connected?
This happens even if the monitor is connected but turned off.

Do you think I should worry?

 

[Zinn]

Do you think I should worry?

I'd worry that the app is wrong and stupid;

 

[sblantipodi]

I'd worry that the app is wrong and stupid;

If I disconnect the power supply the spikes stops

 

[Mr Evil]

Can you see how long the spikes are? I would guess that it's just measuring noise (which power supplies can produce a lot of).

 

[Azrak]

The monitor power supply is a "switching power supply". Google it. Basically, there is a high speed switching circuit that pulses power to charge an output supply capacitor and a feedback voltage sense circuit. Once the voltage in the output capacitor reaches a set threshold, the switching circuitry will turn off since there is no need to keep adding power to the capacitor to increase its voltage. Usually there is a small load resistor across the output capacitor that is designed to discharge it over time when input power is unplugged. So, even when the power supply isn't plugged into the monitor, the switching circuitry must keep "topping up" the output capacitor periodically in order to keep the voltage at the correct level. You said the monitor is turned off, but plugged in. Even when the monitor is off, there is very likely "vampire power draw" (Google it) from the monitor. Those spikes you see in the power monitoring app are likely the times when the voltage in the output capacitor dropped below the minimum threshold and the switching circuitry turned on to keep the capacitor charged. The fact that all three of the supplies you tested behaved the same indicates that this "spike behavior" is intentional. Whether or not the design is good, I have no idea, but it seems consistent and is, therefore, "working as designed."

Additionally, we do not know the frequency of the power monitoring circuit in the UPS or its accuracy and precision. UPSes deal with higher load currents and the monitoring circuitry is designed to detect over-current situations so the UPS can shut down to protect itself, but I've never known UPS monitoring circuits to be very precise nor accurate down to the exact watt. It is possible that the UPS is missing a large percentage of power draw spikes from the monitor power supply because the monitor power supply's power draw spikes are very short. It depends on how the UPS circuitry is monitoring load.

 

[sblantipodi]

Can you see how long the spikes are? I would guess that it's just measuring noise (which power supplies can produce a lot of).

I don't know but I suppose that are very short.

 

[sblantipodi]

The monitor power supply is a "switching power supply". Google it. Basically, there is a high speed switching circuit that pulses power to charge an output supply capacitor and a feedback voltage sense circuit. Once the voltage in the output capacitor reaches a set threshold, the switching circuitry will turn off since there is no need to keep adding power to the capacitor to increase its voltage. Usually there is a small load resistor across the output capacitor that is designed to discharge it over time when input power is unplugged. So, even when the power supply isn't plugged into the monitor, the switching circuitry must keep "topping up" the output capacitor periodically in order to keep the voltage at the correct level. You said the monitor is turned off, but plugged in. Even when the monitor is off, there is very likely "vampire power draw" (Google it) from the monitor. Those spikes you see in the power monitoring app are likely the times when the voltage in the output capacitor dropped below the minimum threshold and the switching circuitry turned on to keep the capacitor charged. The fact that all three of the supplies you tested behaved the same indicates that this "spike behavior" is intentional. Whether or not the design is good, I have no idea, but it seems consistent and is, therefore, "working as designed."

Additionally, we do not know the frequency of the power monitoring circuit in the UPS or its accuracy and precision. UPSes deal with higher load currents and the monitoring circuitry is designed to detect over-current situations so the UPS can shut down to protect itself, but I've never known UPS monitoring circuits to be very precise nor accurate down to the exact watt. It is possible that the UPS is missing a large percentage of power draw spikes from the monitor power supply because the monitor power supply's power draw spikes are very short. It depends on how the UPS circuitry is monitoring load.

This is the mosts informative answer I received. I really appreciate it...
Thank you so much for the time spent answering me, very appreciated.

Do you have an idea on why this happen with the monitor power supply but it doesn't happen with the PC power supply for example?

Thank you very much.

 

[Azrak]

Do you have an idea on why this happen with the monitor power supply but it doesn't happen with the PC power supply for example?

Just different design, I guess. Maybe there is better circuit design in the PC power supply on the AC input side that suppresses inrush current in a better way. I don't know exactly why. You might get better answers on https://www.eevblog.com/forum/ where very knowledgeable people can answer these types of questions.