Mains Definition and 57 Threads

I am currently at a power plant here in Texas and the 480VAC system swings from 480 while equipment is on line and as high as 536VAC when equipment is off line. They tell me that this is prefectly normal but I have never seen swings like this at any power plant. So, is this normal???

So, if I get it right, the basic argument goes like this: AC was preferred to DC because its voltage can be stepped up by a transformer. This limits losses while the current is transported from the production plant to the final user. The voltage is subsequently stepped down when delivered to the...

Hello! I am trying to create a special kind of switch for a project I am working on and I am pretty stumped. Basically, I need to power a 110v fan and light for around 10 seconds with the push of a button, and then have them all turn off and be ready for another button push. My brain immediately...

Hello, If we have a pole top mounted distribution step down transformer for residential use what happens to the voltage on the secondary side if the primary side voltage increase? Thank you

Hi all. Many of you on the forum seem to be very knowledgeable on power transmission. I often notice transmission towers like this on. I know the three large wire groups are the three phases of the AC power, but the towers often have two smaller wires (red circle) on the top. Sometimes they...

Hi, Please could someone explain in detail the arrangements of transmission cables in a UK pylon? In the image below there seems to be 3 sets of two wires on each side. As I understand it UK power stations produce 3-phase electricity so does each side come from two power stations? So this pylon...

Hi, Scenario: Given a powerplant is being provided a constant power source - like steam is being produced at a steady rate, so that the generator rotates at a constant speed, and in turn, produces a constant electrical frequency. And, suppose, hypothetically, all the power being used...

In this example I am thoroughly confused on why Is is divided by sqrt(3). My understanding is that the transformer supplies 3 phase (which is always described in line to line or Y connected). So the current in the winding should be 120[KVA]/230[V] then multiplied by sqrt(3) to convert it to...

No attempted solutions.

My mother has an alternating current extractor fan plugged into the mains. I want to run it at different speeds. I am thinking of using a light dimmer switch to deliver variable voltage to control the fan speed. (An electrical engineer friend told me that it is possible only if the fan is...

Sir how can one explain with the help of an analogy to a grade 10th student the reason behind not getting a shock on touching the neutral wire of the household AC circuit, even though the current flows alternately through live as well as neutral wires.

I used to have a compressor that I used for keeping my vehicle tires inflated to the right pressures, but it was big and bulky (and I had to keep draining it between uses), so I got rid of it a couple of moves back. I'd like to be able to keep our vehicle tires topped off, without the bulk of a...

I don't know whether this question is suited to this forum specifically, but since it deals with electronics, I am putting it here. We have an old air-conditioner, bought in 2007. As you can understand, it is one of the old models running on R22 gas and it switches off the compressor when the...

Does anybody here have experience with whole house power conditioners? We live in an old neighborhood with old overhead powerlines, and it's been a rough fall for brownouts and other little transient "interruptions". I already have UPS's on delicate stuff (basement server, PC, home theater), but...

Hello, I am working on a project to calculate harmonic distortion on a mains signal. The signal has already been stepped down so it oscillates between 0-5V at 50Hz. I looked into some old THD analyzers and it seemed they would generate a clean signal to mimic the fundamental deduct this from the...

A 4160v chiller motor is drawing too much power at start-up. Utility company only let's them run it once or twice a year because of it. It dims all the lights etc.. It was originally a primary reactor starter (2 contactors). The PR was replaced with an auto-xfmr and wired the same. So now it’s a...

Homework Statement Homework Equations I think both A and C are right answers. The Attempt at a Solution 1 condition is pu Z(leakage) must be same on respective KVA rating for load sharing. Now: Zpu = Z(actual)/Z(base) ----equation 1 For Zpu of both transformers to be same, the right side...

I don't understand how this is possible. This is a rather large transformer in a stereo system amplifier. The transformer is a simple step-down with 120V mains primary to a center-tapped secondary providing both 38V and 76V. According to ohm's law, at 120V this thing should draw about 85 amps...

Even though its possible to keep a bus charged from more than one AC voltage sources, what can be the consequences of doing so? My thoughts: - Assuming thst both the sources have similar (but not equal) phase and magnitude, we can expect small circulating currents. Which brings into question the...

All, I could use some help. I would like to measure mains frequency in real-time and pass the data through a high-level programming language (preference of Python). I am not sure where to start with this project, I assume commercial mains frequency analyzer exist, however, my google searches...

What circuit design is used to ensure that the renewable energy source does not begin to absorb energy from the grid (for instance, when its terminal voltage drops below the distribution line voltage)?

Hi, I have quite a superficial understanding of Droop control: http://www.openelectrical.org/wiki/index.php?title=Droop_Control https://en.wikipedia.org/wiki/Droop_speed_control I'm not after a super technically detailed explanation, but if anyone has any more detailed sources for how it is...

if i touch the live (single phase) wire , i will get a shock.But current will have to flow through the body , via the floor , walls of the building , and into the Earth . But cement has electric resistance higher than 1gigaohm so rms current = 220 v / impedance impedance > 1 giga ohm so rms...

Hi, Could I please get some conformation and clarification: So the more phases an inverter has, the less ripple will be on the DC bus, and the higher the switching frequency the inverter is operating at, the closer the approximation is to a sine wave. These are the advantages? But what are the...

Hi, I should know better, but I'm having a mental blank. I was just wondering, if you're doing something using non-linear components on the mains, could be anything, maybe bucking to make a DC supply, whatever. Is it common practice to use an isolation transformer between mains and the...

Does the frequency of the main affect the performance of a microwave oven? Having moved from Europe 50 Hz to the Philippines 60 Hz I can not operate my microwave oven! Is that the reason? How to remediate? Best regards.

Hi folks. I'm currently designing a 4000w LED chip array in which I plan on using 3x 1500w 12v switch mode power supply's. A DC-DC converter will convert the 12v to 35v powering two chips. This totals to 20 step up converters and 3 switch mode power supplies to drive the proposed 40 100w chips...

Hello, I am wondering if anyone can provide a solution to a problem I have come across at work. I have a 360 rotating platform for photography being installed in a couple of weeks and need to a solution to providing power to the objects I put on it. To give you a bigger picture we photograph...

my electric supply company some time supply very low voltage which cause damage/burn out my Tv three time do you know any sort of device which disconnect power supply to my Tv and my Tv un harm from low voltage my electric company uses 220 volt supply or british system. please help me

If drift velocity of electrons changes in AC, how does electricity flow through a circuit to then lose potential energy to the devices in the circuit? Also considering the change in direction, does that mean that the live wire and neutral wire also switch roles in AC mains? I am very confused...

From textbook: "In much of the world (Europe, Australia, Asia) the rms voltage is 240 V, so the peak voltage is 340 V. The line voltage can vary, depending on the total load; the frequency of 60 Hz or 50 Hz, however, remains extremely steady" Why is it so important to keep it steady? what...

Hiya Does anyone know if there's any safety or performance issues with going about the input voltage of a transformer? The spec on maplin says on just about every step down transformer that the input is (x)v-230v. As I live in the uk, mains voltages are 240v a.c. Not sure about what to do

What is the frequency of mains electric noise in the uk?

Homework Statement Find k. Homework Equations If (10)9 + 2(11)1 (10)8 + 3(11)2 (10)7 + ...… + 10 (11)9 = k(10)9 The Attempt at a Solution dividing both sides by 109, 1 + {2(11)1}/(10)1} + {3(11)2}/(10)2} + ..... + {10(11)9}/(10)9} = k 1(1.1)0 + 2(1.1)1 + 3(1.1)2 + ... + 10(1.1)9 ∑(from...

OK so I've always wanted to learn about how the mains power works in conjunction with things that you plug in ie. phone chargers, computer PSU's, TV's etc. Now I know here in Australia that in the home we get 240V AC at 50Hz with the standard 3-pin outlets rated at 10Amps. What do the 3 pins...

Hi all, I would like to ask for suggestions on how to measure the frequency from my main supply which is 240V? As i know the frequency varies very little, hence i would like to measure it as accurate as possible. The reason for this is because I'm doing a smart meter project with Arduino...

Need to do something which requires adding a 2V DC bias to power coming out of the wall (120V, 60Hz), going to a motor. Basically need the 2V DC bias across the motor windings. Motor windings have about a 10 ohm DC resistance. I have a DC power supply that has a max voltage of about 50V...

I want to get a larger flow rate out of a common 3 speed induction motor desk fan. Without forking out for an off the shelf VFD, I thought perhaps I could build a frequency doubler using a bridge rectifier. Following the circuit from left to right, I'm thinking that I'll feed the 240V...

This may be in the 'you were afraid to ask' category. There are many devices which work on batteries or alternatively when plugged into the mains. You can recharge the batteries. Obviously when you are using batteries alone they have to have been charged. Now I am finding that while some...

What would be the direction of the current from the mains till it completes its one full path and the appliance used in the circuit starts working? See attached image.

Hi All, Currently Iam working on a project where I have to superimpose High frequency component on AC mains 240V 60HZ. ( Its imposing Ripples in mains voltage... as happens when voltage is generated from a Petrol generator). Need some help how would i do this ? Thanks in advance. Shakey...

Homework Statement There is this experiment regarding the frequency of AC mains using a sonometer and I found a slight confusion with the formula. there is an electromagnet attached to a step down transformer and a wire is placed below the electromagnet, and by varying the length and tension...

Is it safe to loop the inverter's output neutral to loop with the mains neutal?? Guys, I need a help on this. I thought that it is rather safe to loop one of the output terminal of the inverter to loop with the mains supply inverter, so that there doesn't arise the need of extra neutral wiring...

Hello. I've been reading numerous texts about mains electricity but I'm not getting some of the things. I'll start with some questions, considering Live, Neutral, and Ground wires. 1) Does the neutral wire return/come from the supply company? In that case, where does the company connect the...

Hi Suppose my phone charger is connected to the mains but the phone is not connected. The circuit is not complete because the phone should be there to make the connection complete. That means current is not flowing? That would mean the charger could be there connected to mains all the time...

We often use screw driver testers, where we touch one end of the screw driver with our finger and put the pointed end into the mains. The bulb inside the tester glows, indicating that the mains are active. My question is, how is the circuit completed in this case? If charge flows from our body...

Hello, I have constructed a Faraday box with alluminium sheets having holes on them. The problem is that the mains supply field is not canceled within this box. The box is about 50cmx50cm and hosts a number of electrodes and an electrical drive that moves these system of electrodes. I...

Hi. Sometimes it happens that if you have a lightbulb and something else that is rated high wattage in the same mains outlet (sometimes even on different outlets), and turn the high-wattage appliance, you can see how the lightbulb gets dimmer. Why does this happens? Thanks.

hello all i wanted to make a circuit that takes power from the main a.c supply and increases its frequency( from 60 or 50Hz to about any frequency (lets say about 150KHz? or 15KHz?)), but the output voltage should not drop less than about 25 or 30v...

In parts of Brazil, the mains voltage is 127V AC. Is it safe to use an appliance which is supposed to take 117V AC in this situation? Thanks