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Questions tagged [mains]

Mains electricity, typically a higher voltage AC waveform used to deliver electrical power to households. In North America 120V, 60Hz, in most European countries 230V, 50Hz. What most people will plug appliances into.

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Can I use a RF and/or Time-domain reflectometer to find 'wet contact'?

Friends of mine have a circuit where the RCD trips but only after prolonged rain. There are a number of garden and security lights on that circuit so I very much suspect there is a junction box where ...
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38 views

Question on Ground/Neutral connection for a 220V equipment

I sketched the following schematic from a motor controller board that has to be operated at 220V from L1 to L2. The earth wire is connected to the chassis of the machine. Where I live, it's common to ...
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Electrical safety measures in LED bulbs for the European market

Which electric safety measures are required to introduce LED bulbs on the European market? Which electric measures prevent that the plastic LED bulbs will melt down or ignite at the end of life? I ...
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Designing an inverter with its DC volt and gnd connectors as multi-pins along the PCB, how do i lay out my decoupling capacitors?

Should I distribute multiple decoupling capacitors along the connector rails? Or Should I have a few large capacitors centralised? Is there a mathematical way to evaluate this? Any other methods ...
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41 views

on a network analyzer's measurement what's the meaning of a negative PF?

on a 1 MVA transfomer, process in the place is plastics injection machinery. On the plotted data from an analyzer results in PF jumping from 0.998 to -0.997 (roughly) for all the measurement period ...
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68 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, ...
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118 views

Calculate Angle for Triac Phase Control

Triac-based phase control of the mains power into resistive load. According to this post, https://www.physicsforums.com/threads/how-to-calculate-rms-voltage-from-triac-phase-angle.572668/#post-...
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44 views

What fuse to select for a 240W power supply

I have a 12Volt 20Amp 240Watt regulated power supply to use for a table top pinball game - comprising of solenoids (2@ 12V 8A peak), some LEDs and a micro controller. The unit has an internal fuse but ...
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49 views

Transformer Damage

I recently tried making a HV power supply as per the link (I know it’s very dangerous, lesson learned). I used a pencil type ignition coil in series with a light dimmer and a 5nf capacitor. I ...
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1answer
26 views

Rocker switch & Electronic Relay switch circuit (240v)

I have an already existing circuit between the mains wall supply and a window shutter (see image), it has a gewiss rocker switch for opening and closing the shutter when you press and hold one of the ...
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131 views

“Live neutral reverse” and “hot/neu reverse” difference?

I've got a "Meterk GFCI Electric Socket Tester" that can detect "live neutral reverse" and "hot/neu reverse" cases. Meterk E2752 What could be the difference between these cases? Isn't "live" a ...
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77 views

4 channel digital scope

I wish to view 3 phase waveforms from an alternator (DUT) through isolation transformers via a digital oscilloscope. A 4 channel oscilloscope is obviously ideal for this as I can view the waveforms as ...
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1answer
113 views

What is the purpose of a reset button on power strips?

I'm just curious why would someone put a reset button on power strips in which don't usually implement any digital circuitry. I'm sure it's not for discharging any capacitors, since power strips don't ...
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54 views

Small device to detect AC outage

I want to create a small device that detects AC outages and sounds a buzzer powered by a battery. I have some experience working with arduino and DC electronics but I have no experience in working ...
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67 views

Why do we have “live” and “neutral” wires? [duplicate]

Our house wiring is AC. I thought that AC means we have current flowing from Wire 1 to Wire 2, after 1s/Frequency it flips and current flows from wire 2 to wire 1 and this goes on and on. I heard ...
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Pros and cons of centralised vs decentralised power deliver for small devices

How does compare using one power supply for multiple devices vs each device having its own - regarding efficiency eg. power consumption? Model situation: Home automation using low power devices such ...
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1answer
47 views

Supplying relay board with mains voltage [closed]

I bought a relay board (this one) that can handle 10A at 250V, my question is: if I wire a mains supply into it, say from a ring circuit (that powers sockets throughout normal houses). Will the relay ...
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42 views

During the positive cycle of US AC MAINS Electricity is the secondary Voltage back EMF or in phase with the AC MAINS?

The Sine wave of AC Mains in the US starts at zero and increases to Vmax~169-Volts. in the beginning magnetic Flux Change is greatest as it is proportional to the slope of the AC Sine wave (which is ...
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82 views

Do 240V AC switches only need to open the active wire?

I want to add a simple inline switch to a small, mains powered lamp (~240V AC, 10W Max). It's earthed; it has a typical 3-core cable with a 3-pin plug. I bought a bunch of switches, expecting ...
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1answer
62 views

How much power do power stations in parallel supply?

In modern power systems, the power is supplied by effectively connecting multiple generators in parallel. However, not all these generators are equal, some stations supply more power than others (I ...
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125 views

Is there a practical way to create/inject some visible interference into a nearby AC mains?

I have this 230 to 6V rms step-down transformer. I use it to observe the mains voltage. But recently I needed to create some interference or spike in the mains. So I first tried the following: I ...
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1answer
90 views

60 Hz signal between thumb and forefinger? [duplicate]

I was playing around with the oscilloscope and noticed when I measure between two points on my hand, I see about a 1 V signal at about 60 Hz. Do I oscillate at 60 Hz? Does this have anything to do ...
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1answer
102 views

Powering ESP32 project from mains power [closed]

Apologies if this question was already asked, but my searches didn't end up very consistent on this matter. I want to build a curing chamber in an old small fridge and I thought the ESP32 board will ...
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1answer
78 views

What is the typical voltage of power distribution in rural North America?

I mean the electrical utility power that connects to the transformer outside of the home or other buildings. i.e. what is the primary winding voltage of the transformer having 220 VAC center-tap ...
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2answers
111 views

Why does the power strip's switch light turn on even when the switch is off when I plug in a Schuko plug (CEE 7/7)?

I have a European power strip Schuko socket with switch (it looks like this and this). Mine has 3 Schuko sockets. I cannot open the power strip because it has round head carriage bolts with fastner-...
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2answers
56 views

Rectifier, Flyback vs Transformer, Rectifier, Buck

I've just finished doing my first off-line flyback, which proved a success. A simple block diagram is as follows: I know this topology seems common now, for example it is used in Apple USB Charger ...
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49 views

Linear power supply and mains filtering and protection

I'm designing my first linear power supply for my project which needs dual rail 12V (the regulation from 15V to 12V is on another board, 7812 and 7912). The +12V (+15V) rail will draw about 250mA, the ...
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2answers
45 views

Wouldn't Charge Flow On Power Lines Due to Capacitance

If I touch one line of an exposed power line (say 300 kV AC) and the rest of my body is freely suspended (only in contact with air), am I not forming a capacitor (to ground)? If I am, are electrons ...
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75 views

When tapping single phase power from a 3 phase service, how much power can safely be drawn?

I'm setting up a piece of lab equipment that needs 220v-260v to operate properly. The room it's located in has a a 480v 3-Phase service, in the form of a California Standard 50Amp twist-lock connector....
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17 views

Convert a four-wire relay to work in a two-wire setup?

I'm an electronics newbie who's been working on a project to try to control my baseboard heaters at home. They operate at 240V. I bought a whole bunch of Sonoff Basic WiFi switches, which are ...
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1answer
50 views

Is this fuse on a mains switch adequate?

Given this diagram for a section of a mains circuit (seems like there's no varistor symbol) - simulate this circuit – Schematic created using CircuitLab I gather that it's important for this ...
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Reference material for mains-interfacing circuit safety

I've designed a simple switch/timer circuit for the following environment: Residential installation for North America (technically only for Canada) Single-phase 120Vac Current of switched output ...
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1answer
73 views

voltage control and frequency control [closed]

I am learning on frequency control and voltage control. I am just starting the topic, so I am in little doubt. Does voltage control has any relation with reactive power compensation? How is frequency ...
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1answer
85 views

Need help to newbie to understand MIL-STD-461 [closed]

why only 10khz-10Mhz is used for CE102 test ? why not other frequency range is used for CE102 test ?
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1answer
31 views

If I use a CAT 2 10x probe does my DSO need to be CAT 2?

I need to measure the harmonic distortion on a solar inverter (power output). I need to buy all the equipment from scratch and was wondering if my DSO needs to be CAT 2 rated if I use a CAT2 10x probe....
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4answers
899 views

PCB Layout - Design Critique Requested

I was wondering if I could get some critique on my first PCB layout. I've tried to isolate the 240V side from the 3.3V side as best as I can. Only thing really concerning me is if I there is enough ...
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154 views

How to limit HV capacitor charging current?

I have a voltage doubler, which is connected to mains (without galvanic isolation): It enticed me with its simplicity, configurability and option between charging speed or desulfatability. The ...
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4answers
146 views

Is this line detector safe?

I'm thinking about building a basic AC mains voltage detector. I'd like for it to be both protected and isolated, so I have a zener TVS and an optoisolator. R1 and R3 are chosen so that between them,...
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77 views

ESP8266 Wireless Light Switch - UK Mains

I'm looking at making my UK light switches "Smart" and controllable via Wi-Fi and have come up with the following and wanted some advice on what I have so far: namely, will it work as I think it will ...
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3k views

What is the maximum voltage that silicon can handle?

Today, in a race for efficiency, we have moved from transformers to switching power supplies. Almost all PSUs were designed for single-phase low-voltage operation (220Vac/310Vdc in my country). I've ...
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2answers
309 views

IEC vs. UL current rating

I was doing a search on Digikey for some power entry connectors and noticed that many of the connectors are rated 10A by IEC standards and 15A by UL standards. Why is there such a large difference ...
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3answers
3k views

How could using an ungrounded appliance with a grounded extension cord be a fire hazard?

My local fire department, @Barrie_Fire, recently tweeted (then subsequently deleted) this: Don’t even THINK about using a 2-prong plug in a 3-hole slot! Use only the required number of slots in ...
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4answers
2k views

Measuring AC voltage without a transformer using a microcontroller

As I have no practice with AC voltages, I'm asking if the following circuit is reliable for measuring AC voltages about 110Vca and 220Vca 50Hz/60Hz. I have already made it with a small transformer. ...
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2answers
236 views

Safety design on mains detector

I've designed a simple mains detector which I have drawn below. The theory of operation is pretty simple. A capacitor is used to reduce the current so that my optocoupler can operate (represented by ...
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2answers
233 views

What is this wall-to-PCB connector called?

I'm trying to create my first device involving AC mains. It is a wall mounted energy meter. Essentially, it goes between the outlet and whatever device you want to measure and I'd like to have the ...
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1answer
54 views

How do I identify a what kind of power connector for AC mains is on a product?

I see an AC mains input but I have no idea what kind of cable it goes to, how do I find the cable type so I can design around that? (Or conversely I have a cable and I doubt know what type it is)
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67 views

Can i use a 220v power strip with usb ports on 110v? [closed]

My local power is 220v and i have a power strip that i bought locally. I'm travelling to a country that uses 110v and i wish to bring the power strip there. Is it safe to use my power strip there? ...
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4answers
92 views

Is a motor-generator set a reasonable way to get the purest waveform electricity?

It looks like audiophiles go as far as installing separate powerlines to power their high quality audio systems. The motivation is that the amplifier and other hardware would run cleaner when the ...
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1answer
50 views

Mains Filter for Power Line Comunication

I have two questions about Mains filters and their impedance effect on PLC. 1) With respect to signal propagation relative to the Line impedance: As the signal is sent, via the power line, it will ...
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1answer
114 views

I have an outlet adapter that is clicking at 260bpm. What is happening? [closed]

I plugged this adapter, GE Grounded Adapter-Spaced Six-Outlet Tap, into my outlet the other day. I noticed a clicking noise in my apartment, and it's coming from the adaptor. I used an online app to ...