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Questions tagged [ac]

This tag refers to alternating current mains power. It usually applies to voltages with >100V RMS, but can also be used for ex. 24V industrial AC power.

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5answers
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Three phase systems - are there any single phase devices that are connected between two phases instead of between one phase and neutral?

In star system, single phase consumers are connected between a line and neutral but are there any single phase devices connected between two phases (would that even be considered a single phase device?...
4
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5answers
3k views

why neutral does not shock. how can a neutral be neutral in ac current? [duplicate]

When I probe my city mains with one probe in the live and one in earth (which should be 0 volt) it shows a voltage of around 250v. But when I probe the neutral and the earth it shows no voltage. I ...
6
votes
3answers
2k views

Identification of an AC transformer

I have a broken Philips alarm clock FM/AM radio broken, so I stripped some parts out of it. One of it seems like an AC converter, but I cannot find any reference/datasheet about it. Do you have any ...
0
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3answers
82 views

Understanding this comparator circuit for AC voltage protection

The circuit shown below is taken from this whole design. I understand the main idea. They want to measure some voltage condition and trigger something else with the comparator. R39 and C38 form a low ...
0
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1answer
47 views

Three phase systems - when is potential of a star node equal to zero?

I had to find total impedance of the following three phase circuit with symmetric line voltages: I've been told that nodes 1 and 2 can be connected because their potentials are equal (zero).After ...
0
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1answer
74 views

Will this High Frequency AC Signal Generator Circuit work?

I am going to make a variable DC to AC (10-100kHz). The circuit controlled by 2 PWM Signal from microcontroller to drive NMosfet connected to pull signal from two Ferrite core Transformer primary ...
0
votes
1answer
55 views

Connecting two motors in series [closed]

I have a 240-volt mains supply and I want to run two identical BLDC motors rated at 120 volts each. Without the need for a transformer with just the help of IGBTs and inverter can I run the motors? ...
4
votes
1answer
89 views

Why are overhead electric wires allowed to have higher voltages than third rails for rapid transit railways?

I hope this question is on-topic for this site. The city I live in (Chennai, in India) got a rapid transit metro rail a few years ago that uses overhead electrification of 25kV, 50Hz AC voltage to ...
0
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5answers
103 views

Detecting if 120v AC wire is live with a 2 or 3 VDC line

For a background, I have 3 DPST bistable (latching flip-flop) relays that I have 120VAC input and 2 outputs. On one side, I have a 120VAC appliance. On the other side I need to find a way to feed it ...
0
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1answer
127 views

When oscillating a piezo, should I use AC or DC square wave?

I have several piezoelectric stacks that I am trying to get to shake/oscillate. An example of what I mean by piezoelectric stack is something like Thorlabs PA3CEW. The drive voltage is specified as ...
0
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2answers
99 views

Why does dropping my laptop's AC adapter in the floor make it work again? [closed]

For several months now I've had trouble getting my AC adapter I use to charge my laptop to work. It's one of those typical looking things, with two ends and a big bulky rectangular thing in the middle....
0
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0answers
27 views

How do i control the speed of exhaust fan as the same way of controlling household fan? [duplicate]

I want to control the speed of this exhaust fan the same way household fan speed regulator works (The speed is discrete, using 0,1,2,3 button. the higher the button the faster fan spin) how do i do ...
0
votes
1answer
69 views

SMD capacitor damaged - use of X2 class

I have a question about the need of the use of the X2 capacitor. I have a simple design which can be connected to AC line and I not use an X2 class capacitor but I m using an SMD capacitor from Murata ...
2
votes
3answers
91 views

Why are core losses mechanical and not electrical in an AC power flow diagram? [closed]

The power flow diagram of a generator (a) and a motor (b) are shown. But why are core losses mechanical losses?
0
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1answer
97 views

Coil Damage Worries [duplicate]

I was trying to make a hv generator from an ignition coil. I bought one from the local mechanics, and put it in a circuit in series with a capacitor and a light dimmer connected to mains 240v. The ...
0
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0answers
43 views

transfer function on this problem ac circuit

Have a look at this circuit. I am to find the transfer function in this circuit which has to entries. Model two proposed circuits, where the inputs are vi1 (t), vi2 (t) and the output is assumed v0 (...
1
vote
1answer
29 views

I want to handle the voltage and current spikes from inductive load of 220V AC ceiling fan

I am trying to regulate speed of 220V ceiling fan from Arduino but unable to handle the reverse voltage and current though I am applying the flyback diode across inductive load.
1
vote
0answers
53 views

How do portable batteries with AC outlets handle the ground pin/wire?

There are many portable batteries ("power stations") that have AC outlet(s) with – what looks like – a dummy ground pin. From what I can find in their manuals, it doesn't seem like these devices are ...
0
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0answers
26 views

Generator data for synchronizing

I have two DG sets which are to be synchronized on to the same AC bus and needless to say, they must share load. I have gathered some parametric data which I felt would decide how well these can work ...
0
votes
2answers
136 views

Mains AC Reverse Polarity - Has this damaged my fridge/freezer PCB? [closed]

In the UK, I had a smart meter installed a few weeks ago. My 4 year old Panasonic fridge/freezer (NR-B53VW2-WB) was working fine before the electric meter switch. After the install, after the engineer ...
0
votes
1answer
100 views

How to avoid signal interference between 5 volt analog video signal and 415 volt servomotor and drivers, when working nearby

I am using a 5V borescope analog camera (Sony CCD, PAL/NTSC) for visualization purposes. This camera has a 20 meter 4 core wire, which transmits power and video signal to and from the camera. Along ...
2
votes
2answers
77 views

Live wire and ground question

I am trying to fully understand the danger of AC voltage but still I have some questions... I understand that human body has a capacitance that facilitates AC current penetration. I also understand ...
0
votes
1answer
47 views

Resources for power engineering career [closed]

For long version, include bracketed text. I am 1.5 years into my career as an electrical design engineer doing MEP/architectural-type engineering, with a BSEE and I passed my FE exam. We do equipment ...
1
vote
2answers
80 views

Building an ac electromagnet

I want to generate a sinusoidal electromagnetic field of a specificed frequency between 30-80 Hz. For that I was going to pass an ac current to the an electromagnet. What do I generate an ac current ...
0
votes
2answers
61 views

When to use step up and step down transformer

Well I once saw a video in which a guy made a spot welder using a step down transformer and in another video I saw someone make arcer using a step up transformer. Why using a step up to jump arcs and ...
0
votes
1answer
50 views

help calculating AC capacitor

I'm a DC guy but I think my calculations could work in AC too. I just need confirmation before start putting things together Ok, I have a 3D printer it draws 5amps, 220 volts its internal power ...
-1
votes
2answers
174 views

Can a stripped USB charging cable electrify you and how dangerous would it be? [closed]

I have a USB type C charging cable that I charge my cellphone with. Couple of days ago I found out that it got frayed on some parts of its plastic cover. I always charge my cellphone in bed and before ...
0
votes
1answer
82 views

How to connect an AC line filter

I am trying to connect an AC line filter (rated for 115/250VAC) on the load side of a 24VAC transformer (part# BPD2G, datasheet here). The first filter model I used is Delta's 03DBAW5. From the ...
1
vote
1answer
77 views

Admittance, Conductance, Susceptance definition

Admittance is the reciprocal of impedance. But: 1) Susceptance is the reciprocal of reactance, or the imaginary part of admittance ? 2) Conductance is the reciprocal of resistance, or the real part ...
2
votes
1answer
80 views

AC Diode Question

I am a noob in electrical circuit boards. I need to build a basic circuit board that allows me to open 2 valves at a time but the current should not flow to open an other valve down the circuit if ...
0
votes
0answers
35 views

Is this schematic on the track to create a AC clipper voltage and current regulator?

Good evening I'm trying to make a "clipper" circuit for an AC Voltage source that feeds 2 6V light bulbs rated at 10W and 5W. Problem is that the generator at idle speed produces 4V and at maximum ...
0
votes
1answer
105 views

How can I find the slip speed of a slip ring induction motor without knowing the rotor speed (rated RPM)

The Rotor of a 4 pole, 50hz slip ring induction motor has a resistance of 5ohm per phase and inductance of 150mH per phase. Calculate the slip speed at which max torque occurs. I have used Ns = 120f/...
0
votes
2answers
108 views

Dc Motor giving ac as well as dc voltage when used as generator

When I rotate the rod or the moving part of motor and probe its output through a multimeter (set on ac measuring) it shows around 0.50 volts. When I set the multimeter on dc measuring, it still shows ...
0
votes
4answers
56 views

Creating higher voltage from DC motor?

Is it possible to take a regular dc motor, use it to spin some strong magnets over some coils, and get a higher voltage than what's being used to drive the motor? I was thinking; if you're able to ...
20
votes
5answers
3k views

Why is only the fundamental frequency component said to give useful power?

In most books it's said that the harmonic content in an AC line does not transfer power (just the fundamental frequency does), but no explanation. It seems intuitive, but why is that true? Edit: In ...
0
votes
1answer
61 views

What is the advantage of concatenating two nMOSFETs M1,M2 with Source of M1 connected to Gate of M2?

I am trying to understand the circuit in the figure here : I hope I analyzed correctly its gain (for small AC signal). My small-AC-signal-circuit is attached in the bottom of this post). However, I ...
9
votes
4answers
3k views

Will my circuit charge the battery and power Arduino?

I am currently attending High School, so I don't expect too much here. I simply want to know all the recommendations for this circuit (Capacitor values, etc). But I mainly want to know if this ...
7
votes
3answers
1k views

Glitch in AC sine wave interfering with phase cut dimming

My company installs ZigBee-based phase cut dimmers for bulbs and LEDs (those which support phase cut dimming). Recently, we encountered a site where we faced a flicker issue. The light is slightly ...
0
votes
4answers
55 views

Phase control universal motor dimmer

I need to control the speed of a 220v universal motor using arduino and I am thinking to use an atteny85 ic with a phase control circuit (ltv814 to detect zero crosses and moc3052 to drive a triac to ...
0
votes
1answer
48 views

What is the difference between 3 and 4 Pin IEC320 C14 Power Sockets?

What is the difference between 3 and 4 Pin IEC320 C14 Power Sockets? Looking at the picture attached from reseller I cannot see what the 4th pin serves and I cannot find a description anywhere short ...
0
votes
1answer
54 views

Running STP and high-current AC cables together

I am about to install a backup generator about 40m away from my house. There is no question what cables to run for the AC current (which will be 230V 50Hz up to 30A) — doubled 10AWG (6mm2) to keep ...
2
votes
1answer
83 views

EL Wire safety? [closed]

Electroluminscent wire is often used on party-shirts or to decorate other wearables. They come with little "EL Inverters" that run on 3-12V DC power. I measured the output voltage that's output into ...
0
votes
1answer
74 views

Cap in Series with a DAC Reverse Current

I'm using a 8-bit DAC: (DAC5311IDCKR) to generate a 1.5V Amplitude sine wave with a 3.5VDC offset. I've put high-pass RC filter across it shown below to block DC so that it becomes AC. I understand ...
1
vote
0answers
42 views

Maximum power transfer theorem [duplicate]

Im very stuck on where to go with this question. The examples in class used complex numbers, where as this doesn't seem to need them. Im aware that Zs = Zl, but does Zl=Cl+Rl? Any help with how to ...
2
votes
1answer
72 views

Are large pulsed currents the most deadly type of electric shock?

As opposed to sustained electric shock via DC or AC? I might be wrong, but when people are killed by electrocution it is usually due to a large current of very short duration passing through their ...
1
vote
3answers
238 views

Physics of Dirty Electricity? [closed]

I've been reading about "dirty electricity" lately and while I know there's much controversy whether it causes adverse health effects this question is not about that subject. I'm simply trying to ...
0
votes
1answer
93 views

Is this mains switch on the Neutral or on the Live wire? [closed]

I'm changing the chandelier in my living room and I would like to double check whether its switch is on the live or on the neutral wire. I have a test lamp which is rated to measure 125-250V. There ...
0
votes
0answers
66 views

How to get AC power supply for projects?

So im planning to do electrical and electronics projects in my upcoming 2 month summer vacation. I bought some books for this (Example Getting started in electronics by Forrest) But I soon realised ...
0
votes
1answer
44 views

Clearance distance and resin filler

I'm designing a circuit to detect presence of AC line voltage. It's actually a very simple device with AC side made up of a 200Kohm 1W resistor and an optocoupler and a protection diode. There will be ...
0
votes
1answer
42 views

AC signal analysis: Voltage dip (amplitude dip) at time = 0

I'm working on a series RLC problem where the input voltage is a sinusoidal function for all time. The catch is, for t < 0, the sinusoidal function is of greater magnitude than t >= 0. There is no ...