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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Electrical pump affecting other devices [closed]

I had a swimming pool pump (1) and next to it a device (2) that measures the Ph and other stuffs with smaller pumps to add chlorine, etc. Both devices where connected to sockets next to each other, ...
Carlos Garcia's user avatar
-7 votes
1 answer
85 views

How unequal current flow is created? [closed]

In this video at 0:38 men talk about unequal current flow, how/why this flow is created and why this increase electromagnetic radiation?
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Earthing connections in cascaded UK mains power supply

I've just looked at a power supply for a client to try and diagnose some other issues, and I noted that the connections weren't what I expected. The supply is cascaded, one isolated UK mains to LV DC ...
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Zero crossing circuit with phase control

Beginner here. I am trying to make a "zero crossing" circuit with phase control. This is probably not the right name for the circuit. Basically, I have a sine wave (from the power outlet) at ...
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Measuring if a capacitor on mains is turned on by measuring radiated electrical fields far away

There is a house connected to German mains with hot, neutral and ground. Some distance away in the village there is a PWM source (most propably a solar inverter) which shows as 17kHz on the mains ...
Hansebenger's user avatar
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3 answers
46 views

Positioning of Inductor and Capacitor for Mains Voltage Noise Filtering

In the datasheet of this power supply, it is recommended to place the capacitor before the inductor for the mains voltage filtering circuitry, as it is shown on this image featured on the datasheet: ...
Dinis's user avatar
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Handling higher clamping voltage of IsoMOV - MOV/GDT Hybrid

I'm working on an ac mains control circuit and came across IsoMOV a new hybrid MOV/GDT for surge suppression. This appears to be a straightforward replacement for a standard TPMOV with additional ...
fivejeez's user avatar
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1 answer
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Phase neutral earth fault indicator circuit

I came across the following circuit on a random website: Source website My guess is this circuit is used by some extension boards as shown below: I understand that LED1 current (around 2 mA) is ...
Whiskeyjack's user avatar
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What is the most efficient way to detect if AC mains is live for interfacing with a microcontroller?

I want to implement an electrical mains level detector to interface with a microcontroller the simplest and most efficient way possible as this circuit would always be on. I’m trying to detect when a ...
fivejeez's user avatar
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1 vote
2 answers
554 views

Charging a mobile phone and laptop using wall plug - Series or parallel circuit?

I'd like to understand if charging multiple devices using the 240 V line's main power plugs forms a series or parallel circuit.
9_daytona's user avatar
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1 answer
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Seeking a good solution for mitigating the effects of high in-rush current caused by an AC-DC converter [closed]

Many AC-DC power supplies (say, 220VAC to 24VDC) have huge inrush current values. For example, a device might have an inrush current of 80A@230VAC. This raises the question of how to handle the ...
Dmitri Nesteruk's user avatar
2 votes
1 answer
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AC line filter polarity

Currently I working on very simple AC power mains distribution board. I want to use PCB-mounting AC line filter SCHAFFNER FN405-10-02 for EMI reasons. The datasheet provides simplified schematic: ...
plumbum_by's user avatar
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2 answers
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For an active power factor correction circuit (PFC boost,) is there any characterisation graph between input voltage and power factor?

Just like the regulation graph (ouput voltage vs. input voltage) for a voltage regulator, is there a similar graph (power factor vs. input voltage) for a power factor corrector circuit? My aim is to ...
Dynamic_equilibrium's user avatar
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2 answers
46 views

Mains transformer input overvoltage protection

You have a mains transformer with switchable inputs, 120V and 230V. In case somebody switches the input to 120V and applies 230V (which cannot be mechanically prevented, reasonably), the whole ...
Michael B. Ortiz's user avatar
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USB Audio interface 50Hz + harmonics noise when either laptop or speakers are plugged in

As soon as I plug in either my laptop or my speakers to the wall, I get an unbearable amount of noise in my guitar recording. Signal chain: Guitar --(1/4 jack)-> Audio Interface --(USB)-> PC --(...
Elite_Dragon1337's user avatar
5 votes
3 answers
116 views

Programmable current-limit on mains

Using an incandescent light bulb in series with a mains-powered device is a well known trick to limit the current used by the device. It's great for testing devices you're unsure of. Unfortunately, ...
Celelibi's user avatar
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Measuring 115 V on microcontroller analog input

I've been tasked with switching a number of 115 VAC, 60 Hz supplies to various pieces of equipment, and monitoring these output supplies on a PIC18. I'm confortable with the PIC and ADC side, but ...
Dan Twining's user avatar
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What is the exact reason for grounding (earthing) of a transformer? [duplicate]

I have some misunderstandings with the grounding of a transformer. As far as I know, the utility transformer's (the last transformer before my mains plug) neutral point (star-connected point of 3 ...
electroeso's user avatar
0 votes
2 answers
145 views

Power electronics on a PCI/PCIe expansion card

I'm not sure if its been done before but how feasible is the idea of building an computer expansion card (PCI/PCIe) that carries mains power on some areas of the expansion card being switched by ...
dazzleworth's user avatar
2 votes
1 answer
122 views

Is it safe to use 250V rated relays with UK mains voltages?

UK mains voltage is 230V (RMS) with a tolerance of -6% and +10%. That gives it an upper limit of 253V (RMS). Lots of relays are rated up to 250V: e.g. the Omron G5Q series has a "rated ...
Rob Gilton's user avatar
2 votes
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Philosophy of safety by Double Insulation

In a Class I appliance, when a fault occurs that brings dangerous voltage in contact with accessible conductive parts, the installation wiring fuse or GFCI will not only shut down the dangerous ...
tobalt's user avatar
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1 answer
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TRIAC controlled fan output on furnace control board not working

At board power-on, the fan output connector has mains (230V AC) voltage without the fan connected, that drops to ~2V AC with the fan connected. At power-on, on the attached display, the board shows a ...
gdee's user avatar
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2 votes
0 answers
124 views

ESP32 with two power supplies (AC/DC + USB) using Schottky diodes

I'm building a small circuit to power an ESP32 with two different power supplies. Normally the circuit will be powered from AC, using a Mean Well IRM-02-5 AC-DC power supply to get 5VDC out of 220VAC. ...
Daniel P.'s user avatar
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1 answer
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Schematic of a simple zero-crossing triac switch

I have a triac in a 60Hz 120V power line (as is often done for dimming) and want it to only switch on the power when the AC voltage is low (widely between -40V and +40V would even be fine). This is ...
bobuhito's user avatar
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19 votes
5 answers
4k views

Why does grid voltage drop at 10pm?

The premise of the question may be the problem so please let me explain first. In my home at night we have a bunch of nightlights and we run a small fan in each bedroom for the noise and/or cooling. ...
Aldus Bumblebore's user avatar
-1 votes
2 answers
2k views

Power supply makes a static/coil whine noise when the power supply is off and the PC is off

I have noticed that my power supply (PSU) makes a VERY slight coil whine/static noise while it is plugged into the power outlet, regardless of the power status of the PC and the PSU. It sounds no ...
P. Z.'s user avatar
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1 vote
0 answers
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Reducing Isolation Transformer Leakage

I watched this video and wonder if its complete separation of primary and secondary coils is the normal way to wind a low-power isolation transformer (e.g., 60Hz 120V 120VA). I particularly want low ...
bobuhito's user avatar
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0 answers
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Connecting GND to PE to improve touch sensors sensitivity

I am designing a smart light switch based on a microcontroller, with touch buttons. The design consists of two PCBs: a low voltage one for power (230 V) and an extra low voltage one for control (3.3 V ...
Elzaidir's user avatar
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0 votes
1 answer
318 views

Minimum wire size for a 32Amp breaker

Problem statement: Sailing boat with a 16A onboard breaker need to connect to a 32A onshore power supply. What is the minimum cable size from the onshore 32A breaker to the onboard 16A breaker. Under ...
CaptainMJ's user avatar
1 vote
2 answers
155 views

How can we safely test a mains powered device?

We have small non-isolated 230VAC devices that transform mains to LEDs running at 32V, 20mA. The lights are directly connected to live, neutral and earth like a standard lightbulb would be. Since ...
sandervd's user avatar
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0 answers
140 views

Controlling TRIAC with PWM from microcontroller

I am looking to control a mains heater with a microcontroller. It seems like most solutions use an optocoupler to signal the microcontroller at a zero crossing and another optocoupler to trigger the ...
Levi Applebaum's user avatar
3 votes
0 answers
58 views

Identifying old Thermal Relay and its operating parameters

I was hoping that I could get help identifying an electrical component from a environmental chamber over 30 years old. It is a Sunvic Thermal Relay Type TDW-AJ 2301, 17A 200/250V AC as shown in the ...
MattG's user avatar
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-3 votes
1 answer
143 views

Should I connect a small DC motor directly to the mains without an isolation barrier? [closed]

I recently found out I'd need to pay upwards of $2k in order to supply my entire house with automated blinds. I feel like I can definitely do it myself for a fraction of the cost. For this purpose I'm ...
php_nub_qq's user avatar
4 votes
3 answers
312 views

Location of Galvanic Isolator in marine installation

Almost every installation diagram I have come across for a galvanic isolator, has the GI installed in the shore power input line as follows: I think can understand how this would make sense for a ...
Rowan Smith's user avatar
4 votes
3 answers
414 views

What is this U-shaped device that seems to be connected to one leg of an overhead power line?

Seen recently in Boulder, Colorado.
bigjosh's user avatar
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1 vote
0 answers
32 views

Does the use of an IEC line connector on equipment require a UL cert?

My client wants to use a 12V SLA with a built-in line-powered charger in his gear. If I add an IEC AC mains line connector does this turkey now have to go through cert?
Marty Schrader's user avatar
1 vote
1 answer
75 views

Monitoring ground mA current via voltage transformer [closed]

The TL;DR Can a voltage transformer act as a milliamp current sensor? They resemble in structure. Explanation I want to build an approximate ground leak milli-ammeter (0.1-30 mA) for some appliance. ...
Meymann's user avatar
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0 votes
1 answer
124 views

How can I power the SMPS with reduced input AC voltage while it's under full load?

I'm encountering a design issue with my switch-mode power supply that utilizes the InnoSwitch3-EP (INN3678C). The SMPS powers up and outputs the required V when the input voltage is 133VAC or higher,...
S_D's user avatar
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1 vote
1 answer
114 views

Is this a viable amplifier circuit?

I am looking to measure my mains voltage input for a power monitoring circuit. This is the first time I have messed with an opamp to read out a transformer, as well as my first time simulating in ...
Jeff's user avatar
  • 201
2 votes
3 answers
109 views

How to safely avoid earth cable? [closed]

I'm a software developer (in the uk) and I've been sent some hardware to use as part of my testing, but the way the non-uk manufacturer is telling me to wire it up sounds very sketchy to me. Its a ...
Sayse's user avatar
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1 vote
0 answers
79 views

Remove 50Hz noise from a system

I am working on measurement circuitry and one of the challenges I have is the 50Hz noise. Is there some analogue circuitry that could be implemented to eliminate this? I am using multiple LDOs to ...
Bilal Afzal's user avatar
6 votes
2 answers
937 views

Is an AC/DC converter with no visible fuse before the transformer inherently dangerous?

I've been using a generic, unregulated mains AC/DC converter (wall-wart) for a very low-power project. It's output was a bit prone to 50 Hz ripple, so I opened it up to investigate how the circuit ...
Wossname's user avatar
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0 votes
1 answer
65 views

Maximum Current in 3 phase ac charger for vehicles

I have seen a couple of AC EV Chargers that take in 3-phase inputs. For US it is 120V. For UK and Europe it is 240V/220V. My question is, I want to design the fuse and other MOV components and relays ...
Jacksmith's user avatar
0 votes
2 answers
64 views

Power Supply Concept; Safety and Completeness - Feedback needed [closed]

I am currently designing a power supply for a circuit I have built. I don’t have a great knowledge about PSUs, everything that I know I have learned in the internet. Unfortunately, my engineering ...
redmlr's user avatar
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2 votes
5 answers
941 views

Purpose of Isolation in Power Supplies

I have a general question. Suppose, I have a PCB, (an electronic device), which is powered from the Electrical socket (from mains grid). Let us assume it is single phase. When the mains power supply ...
Freshman's user avatar
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0 answers
46 views

electrical safety for UK -> NL move

We are planning on moving back into the EU. We have a lifestyle of UK based appliances, and will need to update/refit/replace them all. I see that EN / "Europäische Norm" is very well ...
Owen Beresford's user avatar
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0 answers
56 views

Design Review Request: AC Mains Monitoring

I am designing a PCB to monitor 240v RMS mains with a ZMPT101B and YHDC SCT-013-000 current clamps. I am rectifying with an LS05-13B05R3. I aimed for 32mil clearances and widths with no overlap of ...
Jeff's user avatar
  • 201
9 votes
11 answers
4k views

How do you understand the kWh that the power company charges you for?

I really didn't know how to phrase this question. But here are the details. First I understand the simple 10 x 100 W for 1 hour is 1 kWh. But what I want to know is at what time interval does the ...
Mark Twombley's user avatar
13 votes
4 answers
2k views

Mains Plug Soldering Wires

So I have a few extension leads all are 13A rated but the cable length is too short just 1 metre. It would be cheaper for me to rewire them than buying new extension leads. I bought a reel of the ...
Dave1UK's user avatar
  • 275
0 votes
1 answer
79 views

Measuring Differential mode HF on mains with oscilloscope

I want to measure Differential mode HF 9kHz to 100kHz with 3dB accuracy on my 230V 50Hz mains. Is the following concept good? Let's imagine a first-oder high pass filter with its entry voltage U_e ...
Hansebenger's user avatar

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