I see. It makes sense. But then, another question: motors for big cranes, they also start like that? They do not sound like that.The most hard work a fan does is starting. AC or DC fans
When a fan gets old the bearings are not good and the fan turns hard. (dirt in the bearings)
While a old fan will run at 1/4 power it is not enough power to start the fan. If you started the fan at 1/4 power it would likely not move. Just sit and hum. If you pushed the fan with your hand the fan would then run just fine.
All, well designed, fans start at full power to break loose the bearings and get it moving. After the fan is turning you can back down the power.
First, I have no idea what you mean about ceiling fans needing to start at full speed. I've never seen one that does.I see. It makes sense. But then, another question: motors for big cranes, they also start like that? They do not sound like that.
BTW, risking to delay the thread I started: I recall using PWM for small DC motors. My code created very low duty cycle and they started flawlessly. Sheer luck? Very small load, maybe?
A real stumbling block.
I am not saying they need to. Those (all) I can recall, do start at full speed. In other words: as soon as the switch is ON, the fan is spinning at maximum speed.First, I have no idea what you mean about ceiling fans needing to start at full speed. I've never seen one that does.s)
Not according to this history: http://www.dtvintagefans.org/forum/archive/index.php/t-15378.htmlCeiling fans are typically shaded pole motors and they have very poor starting torque, so it does not take alot to stall them, having said that the simple Triac phase controllers are usually capable of starting a shaded pole motor at low speed if the motor is in fairly good condition, bearings etc.
Large crane motor are a different animal completely, 3ph for one, and also older versions are wound rotor motors for restive control. Now many are VFD control.
Max.
I know what you meant. None of my ceiling fans start this way and I've never seen one that does.I am not saying they need to. Those (all) I can recall, do start at full speed. In other words: as soon as the switch is ON, the fan is spinning at maximum speed.
By now, it seems that Ron hit the nail.
I think it's as simple as that. Every other answer on here is probably just either confusing the issue or completely irrelevant!I suspect the reason they start full speed is because that is the next position after "off."
I suspect the reason they start full speed is because that is the next position after "off."
I like the reasoning. The switch is labeled "fast" so it must be fast. So I am going to relabel my switch.I think it's as simple as that. Every other answer on here is probably just either confusing the issue or completely irrelevant!
Apparently you need a real brain teaser: Why are toggle switches in aircraft and in the US almost always installed with the toggle-up position being on? Now, what about in the horizonal position?I like the reasoning. The switch is labeled "fast" so it must be fast. So I am going to relabel my switch.
OFF comes next to FAST for a reason. Switches are labeled that way for a reason. Engineer(s), that understands motors, chose to make it that way from the beginning.
If people that complain, had much control over switches, then OFF would be next to SLOW.
I have a wife that thinks that with enough complaining the FAST/SLOW will work differently. Forty years of complaining has made no difference. Maybe 41 will work.
While a old fan will run at 1/4 power it is not enough power to start the fan. ... After the fan is turning you can back down the power.
Not true. Many fans have switches that cycle through speeds in a loop with repeated pulls of a chain.The switch for fan speed is "off, fast, medium, slow". It does not circle. You can not get from off to slow or from slow to off.
The switches are all still in the same position. It's your images which have been turned.View attachment 110707ORView attachment 110708or
View attachment 110709orView attachment 110710
I think "O" weighs more the "|" so the "O" should be down.![]()
Yes, switch combined with the pot controlling the speed. No chain-controlled here. They are more and more hard to find locally.Wait, is the OP asking about the wall on/off switch causing the fan to start at full speed.
This is the one:In other words: as soon as the switch is ON, the fan is spinning at maximum speed.By now, it seems that Ron hit the nail.