every electric (non-ceiling) fan I have ever used is operated with a dial with settings off, high, mid, and low in that order. Why does it go from off straight to high? Why not do the more intuitive “get higher the more you turn away from off”?
In: 935
And why is the lowest setting still more than I want?
You are trying to move a fridge around, but it is not moving with the your current power. So you push it harder, once it starts moving you feel like it is easier to push it so you can keep pushing it with your original power.
The Friction for still objects is bigger than the friction for moving objects. So you need a higher power to start spinning.
it is the same reason that almost all fans do that. the motor needs a lot more power to get started than it does to run and low setting might not provide enough kick to get it going.
So, imagine you have a hose that’s connected to your outside tap.
The end of the hose has a twist nozzle (rheostat) that lets you adjust the water (voltage) from full blast down to closed (current).
The tap only has ‘on’ or off’ due to a design flaw. As soon as you turn it on (turn your fan from off to on), the full blast of water comes out of the hose.
When you twist the end of the nozzle on the hose, it begins limiting the amount of water depending on how much you twist it (resistance). Eventually, if you twist it enough, it blocks all the water (fan stops).
To make it easier for you, the manufacturer has put three indentations on the nozzle: High, medium, and low.
Cost, basically.
Certain cheap designs of electric motors require a lot of power to get going – especially when there’s a big fan blade attached to them. The cheapest way to ensure that the motor will get the power needs to start spinning is by putting “high” first.
I’m going to ruin your minute by telling you my fan uses buttons. And goes low med high. AND it has a remote which blew my mind when we got it.
The fan’s induction motor doesn’t produce any torque when it’s at rest, so you need a different mechanism to start it than you do once it’s spinning and inducing a current. Fans have a special shaded pole motor just for starting up; it steals a little electrical energy from the stator coil to give the fan a little nudge so that it can start. The amount of torque it produces is pretty small, so they set it up so that you always have to start the fan in the “3” position.
I just bought an arctic desktop fan and it’s legit. It has complete variable control from a knob, an inbuilt battery that’s good for a few hours, and it charges off a USB c cable so can be used plugged in too. It is silent at low speeds and has a pretty ferocious high setting. If you don’t know the brand, they make affordable and decent pc fans.
I always though it was easier to have the resistor in the switch go from one-two-three resistors in series with the one being high first since it had the least resistance, therefore highest voltage and speed. Any truth in circuit design for that?
ELI5: The “High” first is needed to ensure the fan begins rotating (does not stall) and also turns in the correct direction.
ELI’mOlder: Unlike DC, there really is no “positive” and “negative” with single phase AC. (If you don’t understand what single phase means, don’t worry, you don’t need to worry about it. Single phase is what you have in your homes.) It doesn’t matter HOW you connect the fan to the hot and neutral wires, the fan will SEE the same waveform. (Because the 120V, 60 Hz waveform is symmetrical about the X axis). If you have a multimeter, try this (safely) yourself. Go measure the outlet in your home. Put red in the hot side and black in the neutral side, then switch them. They both measure +120V (or whatever your local voltage is.)
Because of this, we actually need to do some electrical trickery to ENSURE that the fan turns on and spins in the correct direction. Unlike a DC motor or fan, we can’t just “switch the leads” and get the fan to turn in the opposite direction. Because switching the leads does nothing. If you just took a normal AC electric motor, without any of this trickery, there are three things that could happen when you plugged it in.
1. The motor would turn clockwise.
2. The motor would turn counterclockwise.
3. The motor would stall (the “poles” of the “spinny part” of the motor can get magnetically “caught” between the “poles” of the “non spinny part” of the motor.)
If the motor stalls (which honestly is pretty common on a motor without a starting capacitor), it does not matter how much voltage you apply, it will REMAIN stalled (because more voltage would just hold it in place “harder.”) (This is why on some old sewing machines, you gotta “help” it get started in the correct direction.)
Because we always want fans to turn on and run in the same direction (well, MOST fans), we do some electrical trickery. Mainly it’s a capacitor. From what I understand, they use this capacitor to inject an additional phase into the motor to ensure it turns on in the correct direction.
The reason “High” is first is because it requires a lot of current to start an electric motor, and if low was first there’d be a higher chance that it could get stalled. Think about it like trying to start a lawnmower. What’s more likely to start it, a shorter, very hard pull, or a long, very slow pull?
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