All Questions
13 questions
0
votes
3answers
1k views
What is reactive energy?
We know the typical equation for instantaneous power (which can be proven): \$p(t)=v(t)i(t)\$. In sinusoidal steady state (let's ignore harmonics for simplicity), \$v(t)=\sqrt{2} V_{\text{rms}} \cos{(\...
6
votes
4answers
1k views
Free-as-in-beer power from neutral and ground?
I live in a house where each socket has 3 connections,: hot (phase) neutral ground Where: The voltage between hot and neutral is about 220V AC. The voltage between ground and neutral is about 2-3V ...
0
votes
1answer
282 views
Calculating Energy Consumption Using a Current Sensor and Voltage Sensor
我正在创建一个PCBA使用采用霍尔传感器to measure current and a transformer rectifier design to measure the mains voltage. The voltage is 110-240 V, ~60 Hz. I wrote a digital filter and ...
0
votes
1answer
43 views
Where in AC the charge gets its energy again?
I'm quite new to electronics. Most of the tutorials I've watched are DC oriented and it's pretty clear that there's a voltage drop across the DC circuit. When current flows through components in DC, ...
0
votes
1answer
94 views
Energy dissipation of a resistor in an AC circuit
I am given a resistor of known resistance with a sinusoidal voltage across it, and am asked to calculate the energy dissipation between t=0 and t=1. Not sure how to do it. Would I Use P=V^2/R and ...
0
votes
2answers
174 views
What is the effect on kWh if the power company reduces line voltage to a residence? [closed]
We just received our power bill and it is showing a 30% rise in kWh for the past month. Nothing has changed in our home. We were even gone one full week in the month. To make it more interesting, ...
0
votes
1answer
46 views
Energy in a wave
The energy of a wave is defined as w=a^2. w=energy a=amplitude. Does this formula also apply to AC or rectified AC? When two waves with identical polarization, frequency, phase and amplitude ...
1
vote
1answer
92 views
Energy loss and power over one period?
Let's say we have a ferrite core inductor connected to an AC sinusoidal source with period \$T\$. Thus, we have voltage \$u(t)\$ across the inductor and current \$i(t)\$ through the inductor. How can ...
1
vote
0answers
2k views
Detecting AC power flow direction [closed]
I'm willing to design an AC power meter, which can measure power from a solar inverter to the utility grid and vice versa. I am using a grid-tied solar inverter to supply the load. This meter should ...
0
votes
2answers
238 views
What does a RF wave carry? [closed]
Other than an AC (Alternating Current) can a RF wave carry anything else ? How can the energy a RF wave carry be measured ? Would the frequency of the wave be related to the transmitted energy of the ...
1
vote
5answers
1k views
Why and How does Power Plant generate Watts?
I know my question is stupid, it is stupid because I am not understanding it correctly. I thought two of following is required to calculate watts. Voltage, Current or Resistance/(Impedance in AC) is ...
4
votes
2answers
3k views
How do I design a current transformer?
I want to make a Current transformer using toroidal ferrites to measure 220/50-60Hz AC current(40A max). Is it possible? And how can I calculate secondary turns count? Ferrite properties: H = 2000, ...
19
votes
1answer
726 views
Does this device which claims to reduce reactive energy from a house work?
I've opened a device that states that it can reduce the reactive energy from a house, by plugin it directly to the power outlet/wall socket. I think it is a con, so I've opened it and I saw this black ...
