Measuring Voltage with Step-Down Adapters: Questions & Answers

In summary, when Berkeman says The source impedance for your AC Mains power is very low... (bold p added by me), implies that the transformer that is providing this power is rated so the voltage won't sag when you take power from it. Also, the power company is able to deliver such large amounts of power that flipping on a light switch has really no effect on lowering what can be supplied.
  • #1
whiterabbot1
2
0
I am currently building an energy monitor according the the specifications of this site,http://openenergymonitor.org/emon/node/59. I understand how the current is measured but I am confused by the voltage measurement circuit.
I do not understand how the step-down adapter can correctly measure voltage usage from one outlet. I understand that the lights and outlets are in series but I was reading that typically dryers and air conditioners are typically on a separate circuit. So how can the voltage used from these appliances be measured from the one outlet?

Thanks.
 
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  • #2
whiterabbot1 said:
I am currently building an energy monitor according the the specifications of this site,http://openenergymonitor.org/emon/node/59. I understand how the current is measured but I am confused by the voltage measurement circuit.
I do not understand how the step-down adapter can correctly measure voltage usage from one outlet. I understand that the lights and outlets are in series but I was reading that typically dryers and air conditioners are typically on a separate circuit. So how can the voltage used from these appliances be measured from the one outlet?

Thanks.

The source imedance for your AC Mains power is very low, so unless there is a fault somewhere, you can measure you whole-house AC Mains voltage from any outlet in your house. This assumes that your two phase loads are reasonably well balanced (USA comment).
 
  • #3
I know that you can but I do not understand why you can. If you could point me to some good resources that would be great.

Thanks.
 
  • #4
When berkeman says,
The source impedance for your AC Mains power is very low...
(bold p added by me), implies that the transformer that is providing this power is rated so the voltage won't sag when you take power from it. Also, the power company is able to deliver such large amounts of power that flipping on a light switch has really no effect on lowering what can be supplied.

Here's a couple of links that you might find interesting.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/hsehld2.html#c1"
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/hsehld.html#c1"

Regards
 
Last edited by a moderator:

1. What is a step-down adapter?

A step-down adapter is a device used to convert a higher voltage into a lower voltage. It typically consists of a transformer and other components that help regulate and adjust the voltage output.

2. Why would I need to measure voltage with a step-down adapter?

You may need to measure voltage with a step-down adapter if you are working with electronic devices or equipment that require a lower voltage than what is available from your power source. This can help protect your devices from damage and ensure they are operating at the correct voltage.

3. How do I use a step-down adapter to measure voltage?

To use a step-down adapter to measure voltage, you will need a multimeter. First, connect the step-down adapter to your power source and then connect the multimeter to the output terminals of the adapter. Set the multimeter to measure voltage and ensure it is set to the appropriate range for the expected output voltage. Then, turn on the power source and read the voltage measurement on the multimeter.

4. Can I measure AC and DC voltage with a step-down adapter?

Yes, most step-down adapters are designed to measure both AC and DC voltage. However, it is important to check the specifications of your specific adapter to ensure it is suitable for the type of voltage you need to measure.

5. Are there any safety precautions I should take when using a step-down adapter?

Yes, it is important to always follow safety precautions when working with electricity. Make sure to use proper protective gear, such as gloves and goggles, and always unplug the power source before making any adjustments or measurements. It is also important to use the correct voltage range on your multimeter and to avoid touching any exposed wires or terminals.

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