Is an induction motor a good thing for small appliances?

[[email protected]]

Hi, I am researching a food processor (kitchenaid). It has 700 watts,
1 HP, and an induction motor.

I have heard/read that watts and HP mean little as this does not
express the efficiency of the motor. I have no idea if that is true or
not.

Then I read the food processor has an induction motor. I have been
reading about various induction motors on wikipedia and other places.

I am trying to find out why an induction motor in this food processor
is a good thing or if it matters if it is an induction motor.

Thank you for any help.

 

[Tim Wescott]

Hi, I am researching a food processor (kitchenaid). It has 700 watts,
1 HP, and an induction motor.

I have heard/read that watts and HP mean little as this does not
express the efficiency of the motor. I have no idea if that is true or
not.

Then I read the food processor has an induction motor. I have been
reading about various induction motors on wikipedia and other places.

I am trying to find out why an induction motor in this food processor
is a good thing or if it matters if it is an induction motor.

Thank you for any help.

The one food processor that I've dismembered (Cuisinart) had a
shunt-wound (universal) motor, which I thought was an ideal choice since
they have such high starting torque. I'm rather surprised that someone
would use an induction motor in a single-phase application that required
high starting torque -- it seems particularly ill suited.

You are correct that watts and horsepower mean little in consumer
appliances, and that they don't express the efficiency of the motor
(efficiency is a 3rd measure). Consumers do not regularly check the
shaft horsepower of their food processors, so manufacturers can make
some pretty silly claims. 700 watts in and 1HP out is particularly
silly, unless you're on a sci.physics.perpetual-motion.

I think an induction motor in a food processor is not a good thing, to
the point where I question whether that's really what it has. Induction
motors, particularly ones for single-phase service, have poor starting
torque. You can improve things somewhat at the cost of running
efficiency, but not much. Since food processors require _lots_ of
starting torque it's hard to believe that they'd use an induction motor.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

 

[Ross Herbert]

The one food processor that I've dismembered (Cuisinart) had a
shunt-wound (universal) motor, which I thought was an ideal choice since
they have such high starting torque. I'm rather surprised that someone
would use an induction motor in a single-phase application that required
high starting torque -- it seems particularly ill suited.

You are correct that watts and horsepower mean little in consumer
appliances, and that they don't express the efficiency of the motor
(efficiency is a 3rd measure). Consumers do not regularly check the
shaft horsepower of their food processors, so manufacturers can make
some pretty silly claims. 700 watts in and 1HP out is particularly
silly, unless you're on a sci.physics.perpetual-motion.

I think an induction motor in a food processor is not a good thing, to
the point where I question whether that's really what it has. Induction
motors, particularly ones for single-phase service, have poor starting
torque. You can improve things somewhat at the cost of running
efficiency, but not much. Since food processors require _lots_ of
starting torque it's hard to believe that they'd use an induction motor.

Yet, looking at the details of a typical Kitchenaid food processor,
that is the type of motor they say it is fitted with.

http://www.kitchenaid.ca/english/product.php?id=4KFP740

Ross Herbert

 

[Phil Allison]

Hi, I am researching a food processor (kitchenaid). It has 700 watts,
1 HP, and an induction motor.

** Gawd - how big is this beast ??

My bench grinder is only 1/3 HP.

I have heard/read that watts and HP mean little as this does not
express the efficiency of the motor. I have no idea if that is true or
not.

** Watts indicates the electrical power consumption while HP indicates the
mechanical power out.

Seems that two different test methods have been used since 1 HP = 746
watts .

Then I read the food processor has an induction motor. I have been
reading about various induction motors on wikipedia and other places.

I am trying to find out why an induction motor in this food processor
is a good thing or if it matters if it is an induction motor.

** Induction motors have very long, maintenance free lives - plus they are
nice and quiet.

Nearly all fans, bench drills and large electrical machines use induction
motors - so did an amasing Braun juice extractor I once owned.

But, their power to weight and torque /rpm curve is *much* poorer than
common "universal" or AC/DC motors you find with hand held power tools,
sewing machines, vacuum cleaners etc.




......... Phil

 

[Paul E. Schoen]

** Induction motors have very long, maintenance free lives - plus they are
nice and quiet.

Nearly all fans, bench drills and large electrical machines use induction
motors - so did an amasing Braun juice extractor I once owned.

But, their power to weight and torque /rpm curve is *much* poorer than
common "universal" or AC/DC motors you find with hand held power tools,
sewing machines, vacuum cleaners etc.

There is a trend toward using three phase induction motors in newer
appliances, although I thought it would be mostly washing machines and air
conditioners. The recent introduction of inexpensive single chip 3 phase VF
controllers in the FHP and up to about 3 HP range has made it practical to
use three phase motors in non-industrial environments. The motors themselves
are very simple to construct, and are extremely reliable and maintenance
free, with just a rotor, a couple of bearings, and a stator. No external
start/run capacitors are required, and no inefficient shaded poles. No
centrifugal switches or sparking brushes to break or wear out. Just a $10
IC, which includes built-in adjustable speed and torque control, soft start,
dynamic braking, overload protection, and even regeneration. The system
actually works on a DC "link", which could be supplied by a bank of
batteries. The three phase motor is indeed an elegant work of art, pioneered
by Nikola Tesla over 100 years ago.

Paul E. Schoen
www.pstech-inc.com

 

[John Jardine.]

Hi, I am researching a food processor (kitchenaid). It has 700 watts,
1 HP, and an induction motor.

I have heard/read that watts and HP mean little as this does not
express the efficiency of the motor. I have no idea if that is true or
not.

Then I read the food processor has an induction motor. I have been
reading about various induction motors on wikipedia and other places.

I am trying to find out why an induction motor in this food processor
is a good thing or if it matters if it is an induction motor.

Thank you for any help.

Disregarding any technical aspects, an induction motor will usually last for
ever and perhaps more important here is that they are quiet in operation.
john

 

[Fred Bloggs]

Hi, I am researching a food processor (kitchenaid). It has 700 watts,
1 HP, and an induction motor.

I have heard/read that watts and HP mean little as this does not
express the efficiency of the motor. I have no idea if that is true or
not.

Then I read the food processor has an induction motor. I have been
reading about various induction motors on wikipedia and other places.

I am trying to find out why an induction motor in this food processor
is a good thing or if it matters if it is an induction motor.

Kitchenaid is a top-of-the-line manufacturer with a well-deserved
reputation for producing high performance and durable products. The
induction motor and drive technology used in this particular product
most likely represents the optimal solution over a feature set comprised
of a myriad of factors going well beyond the simplistic prima facie
engineering summary data. The modern motor control technology is quickly
obsoleting most of the popular conceptions about the various motor
types, and it is very likely that this device is capable of 1HP peak
mechanical outputs with >90% efficiency. Here is an example of the kind
of control technology available at low cost:
http://www.analogzone.com/grnt0728.pdf

 

[[email protected]]

There is a trend toward using three phase induction motors in newer
appliances, although I thought it would be mostly washing machines and air
conditioners. The recent introduction of inexpensive single chip 3 phase VF
controllers in the FHP and up to about 3 HP range has made it practical to
use three phase motors in non-industrial environments. The motors themselves
are very simple to construct, and are extremely reliable and maintenance
free, with just a rotor, a couple of bearings, and a stator. No external
start/run capacitors are required, and no inefficient shaded poles. No
centrifugal switches or sparking brushes to break or wear out. Just a $10
IC, which includes built-in adjustable speed and torque control, soft start,
dynamic braking, overload protection, and even regeneration. The system
actually works on a DC "link", which could be supplied by a bank of
batteries. The three phase motor is indeed an elegant work of art, pioneered
by Nikola Tesla over 100 years ago.

Paul E. Schoen
www.pstech-inc.com

So I guess I need to ask KitchenAid what kind of induction motor it has?

 

[Ken Smith]

The one food processor that I've dismembered (Cuisinart) had a
shunt-wound (universal) motor, which I thought was an ideal choice since
they have such high starting torque.

You mean series motor. Shunt motors don't work for AC.

 

[Tim Wescott]

You mean series motor. Shunt motors don't work for AC.

Aaargh. At least I got the 'universal' right.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

 

[Tim Wescott]

Yet, looking at the details of a typical Kitchenaid food processor,
that is the type of motor they say it is fitted with.

http://www.kitchenaid.ca/english/product.php?id=4KFP740

Ross Herbert

Having seen what happens between what I say to a marketing guy and what
gets printed, I have to say that I'll believe it when I open one up and
see a lack of brushes.

And from the other thread: series-wound. It's what I meant, I just got
the other 's' word (d'oh).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/

 

[Zak]

I think an induction motor in a food processor is not a good thing, to
the point where I question whether that's really what it has. Induction
motors, particularly ones for single-phase service, have poor starting
torque. You can improve things somewhat at the cost of running
efficiency, but not much. Since food processors require _lots_ of
starting torque it's hard to believe that they'd use an induction motor.

Well, they probably found out that a permanent-magnet motor has even
worse starting torque: these are what's used in pumps for washers these
days. They turn a random direction (which probably clears debris).




Thomas