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39

I have to start with some terminology -- sorry if it's esoteric, but this will bring things into line with how folks talk about this subject. When you turn a permanent-magnet DC machine*, the armature generates a voltage internally. This is called the "EMF"** of the armature, or the "back EMF" if the machine is running as a motor. This EMF is always ...


4

I am making a motor and was wondering if it is necessary to use insulated copper wire instead of any regular copper wire. This depends on what you mean by "insulated". In a motor or any device that uses multiple turns to form an inductor - a device that increases the magnetic field by using a single isolated multi-turn conductor, then the current MUST ...


4

Judging from the motor picture, you have a fairly powerful motor RS-550 class, from some power tool/drill or other appliance. The motor start-up current (or load current) is likely above the capability of your power supply, and the supply goes into sporadic shutdown mode, and back. If your power supply is already giving out just 12 V instead of 18V, it ...


4

I take it you don't have any specifications for the motor showing the acceptable voltage range? Absent the spec, I would be nearly certain that the motor itself would perform just fine on 36V. For the motor controller; the ones I'm familar with for these kind of applications are actually current-limited, not power-limited. So, your 36V 1kW controller will ...


4

"applying a resistive load" to a running motor is essentially how an electric brake works. As a first approximation, the torque produced by the motor is proportional to the current, that's turning the motor is harder as the load resistance gets smaller. When you short the terminals, there's only the internal resistance of the motor which limits the current.


3

As I read the accepted answer my brain came up with the following simplification, which I think is loosely accurate (?): Motors are both dynamos and electromagnets. Turning a motor invokes its properties as a dynamo. Because the motor's terminals are shorted together, the generated voltage is applied to the motor coil windings, invoking the motor's ...


3

The selected fans have brushless motors with electronic control circuits built in. The motor coils are not powered directly by the input power and should not transmit any inductive kickback to the external supply. However there is no indication that the motors are designed for variable voltage operation.


3

If the control circuit power supply also powers electronic control equipment or if the relays are in the same enclosure with electronic control equipment, then every relay should have transient voltage suppression. For AC relay coils, RC suppression should be used. For DC coils, an anti-parallel diode should be used. If the soft starter is electronically ...


3

It makes no difference what it is. It is the component that is protecting the motor from the real problem. The most probable problem is that the motor does not have sufficient power or torque to do the job. There is also the possibility of improper motor use.


3

More turns: higher flux and therefore pulling strength at cost of higher back emf which will drown driving voltage once speed starts to rise. However, to avoid high I^2R heat losses, you may need to use thicker wire (higher volume/weight/cost). Basically, lower RPM means the stator coils will act more resistive than inductive. More rotor pole pairs: closer ...


2

Looks like some sort of a fuse....probably a Resettable PTC Fuse. A Resettable PTC Fuse exhibits the same characteristics as you mentioned. (i.e. getting hot and cutting the power to the motor). When current above the threshold current of the fuse flows, the fuse gets hot and stops conducting. The conduction of electricity resumes when high current or ...


2

Motors have a surge current that depends on acceleration and fans have a steady current that is linear like a resistor. V/I= constant at steady state RPM above start. So the BLDC motors convert DC to AC and the Vdc/motor DCR determines the starting current. But as the fan speeds up backEMF reduces the current. So you have a Buck regulator rated for 80W ...


2

This is a capacitor start induction motor. Most of the field is generated by the main winding, which in this case looks to be in two sections (to allow it to be series or parallel connected to operate at different voltages). Alone this generates no direction of rotation on a single phase, so there's an additional winding, at 90 degrees electrical, which can ...


2

Somethink like that. If you wan't a constant torque controller then you should measure the motor current and adjust PWM duty ratio so that the motor current is equal or less the current setpoint (torque setpoint). simulate this circuit – Schematic created using CircuitLab


2

You could use a generator as a variable load. Use a PWM signal to short circuit the output of the generator. Shorter duty cycle is less load, longer duty cycle is more load. A generator is just a motor whose shaft is turned by an external force.


2

Pardon my ignorance on this application, but I do not know the nature of your load current if that was measured or rated. My understanding is the Load Transfer Switch(LTC) & motor operate in a discontinuous mode of AC start-surge then DC-rapid stop, then idle for <30 seconds in order to regulate the primary grid voltage into the transformer. The ...


2

For only 90 degrees of rotation, I would consider a push-pull solenoid operating a bell crank mechanism.


2

Yes, the voltage and amperage do make a difference. To start with the motor wants to spin at a speed proportional to voltage, so if the voltage is too high or too low the motor will either over-speed or not run fast enough. Over-speeding can produce excessive brush arcing and commutator wear, reduce bearing life, or even cause the armature to fly apart. ...


1

If you apply 180W to the motor when it is almost stalled (ie too much mechanical load), it will melt the motor. If you apply 180W with no load, the motor will spin so fast that it will damage the device. 180W only applies to the rated torque and rated speed, which has about half of the no load speed and half the 0 rpm torque. I, too, was surprised when I ...


1

This is my first attempt at electrical engineering... I am completely ignorant of this field and have tried my best to piece together my understanding of everything i'm working with Engineering is very much about ratings and specifications. You seem to know that you have a 12-volt motor. Is that all you know about it? Where did you get that information? ...


1

It will probably last for ever. Thats not much over and for the short time of a shave. would not worry it the least.


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