The engine and the electric motor

BEFORE POSTING: This thread is STRICTLY about electric motors Vs. Piston
engines with shaft (yes I know engines need a clutch) connected to shaft
duel and therefore no thread should be about their abilities in cars,
the weight advantage they have, or the power source, etc...


Okay now that is out of the way now lets talk about which engine and
motor will win in a shaft connected to shaft duel.

I have here a list of the possible winners from reading up articles and
books.
The list based purely off theory:

DC (direct current) class motors

Series-wound motors will defeat a piston engine with great ease!!

Shunt-wound motors might defeat a piston engine (NOT 100% SURE)

Compound-wound motors will defeat a piston engine

Permanent magnent motors might lose to a piston engine (NOT 100% SURE
if motor were to be designed for special applications)


Single-Phase AC (alternating current) class motors

Induction start/Induction run motors will lose against a piston engine
(and go up in smoke too)

Capacitor start/Induction run motors might defeat a piston engine (NOT
100% SURE)

Permanent split capacitor motors will lose against a piston engine

Capacitor start/Capacitor run motors will defeat a piston engine

Shaded-pole motors will ALWAYS LOSE to a piston engine no matter how
it's modded.


3-Phase AC class motors

NEMA Design A motors will defeat a piston engine

NEMA Design B motors will defeat a piston engine

NEMA Design C motors will defeat a piston engine

NEMA Design D motors will defeat a piston engine with ease!

AC/DC universal motor- Engine will win against this motor.


Applications of where the different motors are used:

NOTE: when I use the term "starting torque" I mean the torque the motor
develops at zero RPM. They DO make torque at 0 RPM. If you need to be
convinced then simply take a weak motor like a shaded pole motor and
lock down its shaft with your hand. Then apply power to it and you will
feel a force against you fingers even though the motor is not rotating.
Another example is your car starter (a series-wound motor btw) which
has to start the engine from a dead stop.

DC class motors

NOTE: all DC motors can be easily reversed.

Series-wound
Pros: Series wound motors are used in heavy lifting applications like
cranes and hoist or for ultra hard to start loads like drilling through
hard rocks in mining or in traction applications like trains. (which is
a hybrid btw) And can be mechanically overloaded many times without
damage.

Cons: A mechanical load must NEVER be removed from a series-wound motor
or it will "runaway" which means it will speed up to the point of
destruction (large ones at least). A very heavy load will result in a
great speed reduction (but ultra high torque). As a result they have
poor speed regulation. Electrical current demanded by these motors is
very high, but they are designed to survive this. Brushes will need to
be changed after a while use and the commutator needs to be machined to
bring down its electrical resistance.

Shunt-wound
Pros: Shunt-wound motors have excellent speed regulation under varying
mechanical loads and therefore are used where speed is predictable
under varying loads such as converyor systems.

Cons: Starting torque is OKAY and therefore the mechanical load cannot
be too great. Brushes need to be changed after a while use and the
commutator needs to be machined to bring down its electrical
resistance.

Compound-wound
Pros: This motor has the characteristics of a series-wound motor and a
shunt-wound motor. So it has high starting torque and decent speed
regulation. This is used in converyor systems that have heavy loads and
in cranes where speed must be fairly constant for certain loads.

Cons: Still cannot compete with the torque of a series-wound motor.
Speed regulation is not as great as a shunt-Wound motor. Brushes need
to be changed after a while use and the commutator needs to be machined
to bring down its electrical resistance

Permanent Magnent
Pros: This motor has linear torque characteristics and speed control.
This motor is useful in traction applications like wheelchairs,
scooters, medium mechanical loads, and small hoists.

Cons: This type of motor is mostly not available in any higher
horsepower than 3, unless special applications require a greater one.
Permanent magnents can be easily damaged and they lose there magnetic
strength over time. Also starting torque is less than a series-wound
motor. Brushes need to be changed after a while use and the commutator
needs to be machined to bring down its electrical resistance. (unless
its a brushless type which in the DC class motors is only available for
this type of motor)

AC-single phase class

NOTE: these motors are not so easy to reverse

Capacitor start/Capacitor run
Pros: This type of motor is used in hard to start applications like air
compressors, cement mixing, and other general severe loads. No brushes
(its brushless) to wear out since this works by induction (look up how
a transformer works).

Cons: Only available up to 10 Horsepower and torque is still not a good
as a series-wound motor. Has a starting switch that will wear out.
Cannot be easily reversed.

Capacitor start/Induction run
Pros: This motor is cheaper than the above. It is used in conveyor belt
systems, large blowers, pumps, and mild loads, etc. No brushes (its
brushless) to wear out since this works by induction (look up how a
transformer works).

Cons: Starting torque is less than a Capacitor start/Capactitor run and
the series-wound motor still has the torque advantage. Only available up
to 10 horsepower. Has a starting switch that will wear out. Cannot be
easily reversed.

Induction Start/Induction run
Pros: This motor is cheaper than the above 2. Mainly useful for small
blowers, grinders, and low starting torque applications. No brushes
(Its brushless) to wear out since this works by induction (look up how
a transformer works).

Cons: Will easily overheat to the point of it smoking if a severe
mechanical load is applied to it. Horespower is only available up to
about 1/3 horse. It pulls in a LOT of current up to 1000% when first
started up!!! Has a starting switch that will wear out. Cannot be
easily reversed.

Permanent Split Capacitor
Pros: Very cheap and is good for fans, blowers, and garage door
openers. It can be reversed easily and is considered the most reliable
of the single-phase AC motors due to no starting switch to wear out. No
brushses (its brushless) to wear out since this works by induction (okay
I will stop telling you to look up a how a transformer works:tongue: ).

Cons: Terrible starting torque.

Shaded-Pole
Pros: VERY CHEAP! This motor is considered a "throw away motor" since
its cheaper to just throw it away rather than have it repaired. Good
for small fans like that in bathrooms, refridgerators, and steam
removers over stoves. Also brushless and has no switch to wear out.

Cons: starting torque is PATHECTIC. This motor is so weak that a human
can use two fingers to stop the shaft from rotating. Also it is at best
only 20% efficient.:disappoin

AC/DC universal motor
Pros: this motor can be ran from AC or DC (Pure AC motors can be ran
from a DC source if an inverter (changes DC to AC) is connected between
the motor and battery). This motor can produce excellent torque for its
small size and its speed is voltage dependant rather the frequency
dependant like that of other AC motors (hence the reason they spin very
fast). This motor is used in power tools, blenders, and vacuum cleaners
where torque/weight ratio/speed is crucial.

Cons: This motor requires brushes and therefore will require
mantainence. The torque is so-so, but is much higher than a shaded-pole
motor!

AC-3-phase class

NOTE: All 3-phase motors can be easily reversed.

NEMA Design A
Pros: This motor is for general apps like conveyors, blowers, and other
mild loads. Torque is greater than any single phase AC motor. Very
efficient. NO mechanical stuff to wear out like switches and brushes.

Cons: electrical current demand can be high. Torque is still less than
a series-wound DC motor.

NEMA Design B
Pros: This motor is used mainly more often in industry than the other
types. General uses are fans, blowers, converyors, small to medium
grinders, and crushers. Torque is higher than a NEMA design A motor. NO
mechanical stuff to wear out like switches and brushes. Very efficient.

Cons: Series-wound motors still takes the winner circle for torque.

NEMA Design C
Pros: This motor is used for heavy loads such as conveyor belts used
for hauling grains to a silo, punch presses, and hydraulic presses.
Torque is higher than a NEMA Design B motor. No mechanical stuff to
wear out. Very efficient.

Cons: Again the series-wound motor has the torque advantage.

NEMA Design D
Pros: This motor is a torque monster like that of the Series-wound
motor. It's used in large oil pumps like seen out in the deserts of
Texas, hoists, cranes, in large ships to propel them forward (hybrid
based types that use a steam turbine to turn a generator which powers
the motor like our aircraft carriers near the Middle East shores), and
in traction apps like that of the newer model trains. No mechanical
stuff to wear out.

Cons: although it still does not have as much torque as a series-wound
motor it IS reliable since it has no switches and brushes to wear out
(this it true for all 3-phase AC motors. The only thing to ever wear
out would be the bearings. It has been known for 3-phase motors to last
up to 150 years or more!)


So what do you all think about my little article?


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I am not sure of your point(s) here. Win you say "win" when referring to
the comparions between a piston and electic, what are the rules?
Obviously the piston engine must be started from a decent RPM, but
beyond that point Torque (and HP) is the issue. So how can you say one
will "win" without stating the HP requirements? A diesel piston engine
of even 10 HP is going to certainly beat a 1000 Watt electrical motor
of any type. But of course a 10,000 watt electrical motor will have the
edge in some rpm range.
What point are you trying to make?

Jim
SR Racing


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> Win you say "win" when referring to the comparions between a piston and
> electic, what are the rules?

I have updated my post. Engine will be ran to its most torque at rated
RPM range.

> So how can you say one will "win" without stating the HP requirements?

Post has been corrected. We will assume hp is the same for all.

> What point are you trying to make?

The point I am making is to educate people that just because an
electric home appliance like a washer machine (it uses a induction
start/induction run motor) or a vent fan (uses shaded-pole motor) stops
turning from a light load does not mean that every electric motor is
weak (which is stereotyping) like that because there are so many types
of electric motors, each with their own torque characteristics.

In fact it makes no sense to use a high torque motor for those two
types of home appliances mentioned since there job duties are a light
mechanical load. You most certainly don't want a capacitor
start/capacitor run motor running a washing machine since they are way
to torquy and can damage clothes or the mechanical drive train of the
washer machine. Not to mention the insane price tag increase from using
this surpreme motor of its class.


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