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AC Power Meter | PSU | UPS evaluation | Battery Testers - Chargers | CCTV => AC Power Measurement of appliances & Technical discussion => Topic started by: Kiriakos GR on August 21, 2022, 11:44:40 AM
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Power meter requirements so to measure mobile phone charger Stand-by power .
Intro:
Most cell phone chargers are switching power supplies.
First, 220V is rectified into DC power, and then through high-frequency conversion, coupled through a pulse transformer, unidirectional rectification outputs low-voltage DC.
Even though there is no output current, the high frequency conversion part is still working and needs to consume some power.
For example, the control circuit in the charger mainly detects whether the phone is connected to the charger.
The control circuit will also function when the charger is not connected to the phone.
Another example is a load element (an indicator of a single charger) that also works when plugged in and also draws a portion of the power.
Simply put, devices like chargers are bound to draw power when plugged in.
The People's Republic of China Communication Industry Standard yd-t1591-2009 "Technical Requirements and Test Methods for Power Adapters and Charging/Data Interfaces for Mobile Communication Terminals" stipulates that the rated output current of the power adapter should be in the range of 500mA to 1500 mA, determined by the manufacturer.
The AC line power consumption is less than 150 mW without the load as power consumption of the power adapter.
The regular chargers we use will comply with the relevant national standards.
The required high precision digital power meter it should incorporates a new design architecture with many optimizations for low power measurements.
It minimum measuring AC current ability should be as low as 50μA (micro Ampere), and to can measure power consumption as low as 0.01W.
Such equipment it does meets the tests of international standards (IEC62301, Energy Star, Low power measuring specification).
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This topic it would never be complete, with out adding as reference European Union product design testing procedures.
About Standby power testing requirements:
According to EU commission, mobile phone charger as an item, this is not considered as different item from cordless phone charger.
Standby power this is measured with cordless or mobile phone attached to the charger and as soon the phone is really charged up (fully).
And or just the charger alone.
About the People's Republic of China Communication Industry they forgot to let us know, that the Chinese factory will skip adding filtering at their switching PSU (small charger).
And because of that fact, and with such a huge amount of electrical noise, a digital single phase power meter its close to impossible this to deliver a stable measurement.
Next major issue the fluctuated AC voltage
Even the best digital single phase power meter, this is not a God, so to able to measure power in Watts, under severely unstable conditions.
From the one hand there is pulsing PSU electrical noise, from the other hand there is AC Voltage, this constantly fluctuating.
In total they are two factors of instability.
The solution:
Cordless phones placed on the market with a base station shall be tested for networked standby power consumption, with the following test settings:
(a) Tests shall be performed on the base station both without the handset on the base station as well as with the charged handset on the base station.
(b) The devices shall be measured in the condition as delivered to the end-user(factory setting).
(c) The power consumptions shall be measured as average power consumptions over a time period of 10 minutes.
(d) The measurements shall be carried out with a mains supply voltage of 230V ± 1 %.
https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=OJ%3AJOL_2023_214_R_0003&qid=1693469612388 (https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=OJ%3AJOL_2023_214_R_0003&qid=1693469612388)
In conclusion:
Any one thinking about him performing Standby power measurements, he must have the proper toolbox.
a) AC mains supply voltage of 230V ± 1 % (output Pure sine wave)
b) Digital single phase power meter
c) Digital single phase power meter this should be able to perform averaging by the use of onboard function, and or due PC software.
If one of these three requirements it is missing from your toolbox?
Then you are not in position to perform Standby power measurement, that this is recognized as a valid one.