Electric Motor Question
Banister Stairwell
3450rpm single phase electric motor. It's rated at 15 amps at 115 volts. I
want to configure this motor to operate on 230/240 volts. It appears that
all I need to do is remove a small access plate on the back of the motor and
reconnect the wires to the appropriate higher-voltage terminals. Aside from
changing the plug, is this all I need to do, or do I need to change the
start and run capacitors as well?
To power the compressor at the higher voltage, I plan to install a 240 volt
receptacle on a dedicated 20 amp circuit. Since this circuit is intended
for a motorized appliance, the circuit must be run directly to the outdoor
service-rated panel, not an indoor sub-panel. Is this correct?
Thanks in advance.
jim
can change it over the 230 volts by taking off the cover off the side of
the motor(probably like yours) and there is a diagram inside the cover
telling you how to move the wires around for getting the 230 volts set
up... it makes no mention of changing any capacitors(i have one on this
motor)
The Masked Marvel
terminal plate.
"Banister Stairwell" <afgan...@bananastan.com> wrote in message
news:Vlsgc.6559$V17....@fe2.texas.rr.com...
Joseph Meehan
I believe all you need to is to change the wires and the supply voltage.
BTW it will then draw about half the amps it did before and many have a
slight increase in performance.
--
Joseph E. Meehan
26 + 6 = 1 It's Irish Math
twiedeman
recepticle is only 15 amp, do you have another recepticle(20 amp) nearby.
Banister Stairwell
news:1086029...@corp.supernews.com...
> Why would you change it? Is it popping your breaker? If your current
> recepticle is only 15 amp, do you have another recepticle(20 amp) nearby.
It's on a 20 amp circuit now and the motor draws every bit of it's rated 15
amps.
I haven't had a problem with the breaker tripping, since it's currently
plugged into the one and only 20 amp dedicated circuit receptacle in the
garage. Unfortunately, this receptale happens to be in a *very*
inconvenient location and I don't want to run the compressor with an
extension chord, nor tie up this one receptacle for the air compressor. I
figure, since I need to intall another receptical specifically for the
compressor anyway, I might as well make it a dedicated 240 volt circuit and
convert the motor to operate on 240 volts.
Besides, the motor won't draw as much current and (hopefully) won't have to
work as hard.
I-zheet M'drurz
> Besides, the motor won't draw as much current and (hopefully)
> won't have to work as hard.
Power is constant. Higher volts * lower current still = same
amount of power. Workload stays the same, as does the effect on
your electric meter. Anybody told you different, they lied.
--
TP / Network Man __________________________________
If u want the races for free,
somebody has to pay for it. ($1 Earl)
Banister Stairwell
news:Xns94CFECF04E5...@130.133.1.4...
> Banister Stairwell wrote:
>
> Power is constant. Higher volts * lower current still = same
> amount of power. Workload stays the same, as does the effect on
> your electric meter. Anybody told you different, they lied.
You're correct, of course.
My thoughts in this case were that perhaps the motor may have been
originally designed as a 240 volt motor, with a built-in wiring setup to
accomodate 120 volts. In other words, running it at 240 volts may be better
in that (perhaps) the motor would be operating more within it's original
design parameters. Of course, this is just speculation on my part. I may
post this question to someone at Emerson Electric Co. and see what they say
(Doerr is a division of Emerson, I believe).
After looking more closely at the information plate on the motor, it does
show that the motor is rated at 7.5 amps at 230 volts. Assuming no
difference in actual motor performance from 120 to 240 volts, and other than
the new 240 volt 20 amp dedicated circuit not being maxed out amperage-wise,
are there any other compelling reasons for converting to 240 volts for this
particular application?
Thanks.
Jeff Prevett
>
> > Besides, the motor won't draw as much current and (hopefully)
> > won't have to work as hard.
>
> Power is constant. Higher volts * lower current still = same
> amount of power. Workload stays the same, as does the effect on
> your electric meter. Anybody told you different, they lied.
Technically this is incorrect. The amount of power delivered to the load is
the same (P=V*I) so the motor will draw 1/2 the current at 240V than it
would at 120V. But when it comes to the 'wasted power', the 240V setup
wastes less power than the 120V setup. Because the 240V setup uses 1/2 the
current, 4 times more power is wasted when using 120V (P=I^2*R). This
'wasted power' is in the form of heat in the wiring all the way back to the
transformer on the street. Also, the windings in the motor will be
producing heat. You ARE paying for the wasted power - it does show up on
your meter. However, this wasted power is so small relative to the power
consumed by the motor, that it can be neglegable.
This is where 240V helps the efficiency of the motor. As the windings
temperature increases, the resistance increases, therefore consuming more
power (therefore more power 'wasted'). Also, the life of any motor is
increased by running the motor cooler.
It would be better to run this motor at 240V because you also don't have to
worry about the motor unbalancing the electrical system. This occurs when
you have too many heavy demands on one phase (I use this term to indicate
180 deg out of phase, not 120 deg as in 3-phase) and light demands on
another phase. This causes a lower voltage on the 120V phase (and thus,
more current consumption) that has the heavy demands and a higher voltage on
the other phase.
Just my $0.02
Jeff
zxcvbob
>
>>I have an air compressor that is driven by a Doerr (model LR22132) 2hp,
>>3450rpm single phase electric motor. It's rated at 15 amps at 115 volts. I
>>want to configure this motor to operate on 230/240 volts. It appears that
>>all I need to do is remove a small access plate on the back of the motor and
>>reconnect the wires to the appropriate higher-voltage terminals. Aside from
>>changing the plug, is this all I need to do, or do I need to change the
>>start and run capacitors as well?
If the motor can be converted to 240v, there will be a wiring diagram
under the access plate that tells you what wires to swap. When you are
all done, make sure the motor does not run backwards! The compressor
should still work going backwards, but its oil pump won't work (if it
has one) and the fan on the flywheel will not blow the right direction.
If the motor runs backwards, usually you just have to reverse the two
wires you moved. Not all motors are reversable.
>>To power the compressor at the higher voltage, I plan to install a 240 volt
>>receptacle on a dedicated 20 amp circuit. Since this circuit is intended
>>for a motorized appliance, the circuit must be run directly to the outdoor
>>service-rated panel, not an indoor sub-panel. Is this correct?
An indoor subpanel is fine. Maybe I don't understand your question.
Best regards,
Bob
Chris Lewis
> After looking more closely at the information plate on the motor, it does
> show that the motor is rated at 7.5 amps at 230 volts. Assuming no
> difference in actual motor performance from 120 to 240 volts, and other than
> the new 240 volt 20 amp dedicated circuit not being maxed out amperage-wise,
> are there any other compelling reasons for converting to 240 volts for this
> particular application?
Running a convertible motor at 240V is always better than running it at 120V,
but the differences are often so small to not be worth doing anything about.
It's all in startup and at high load where the factor-of-four reduction in power
loss in the wiring at 240V over 120V will result in lower voltage drop (dips)
to the motor, easier starting, and longer life.
Compressors are almost always drawing very near full rated amps, and they
are often hard-starting. So this is particularly important for compressors.
The difference gets larger the closer the 120V circuit is to max amps, and
the longer the circuit is. If that compressor was 10A, and the total circuit
was only 20', I'd say, don't bother.
But, your compressor maxes out a 120V 15A circuit, and it's probably significantly
longer than 20'.
If it were me, I'd definately go to 240V. But I would consider leaving it a 15A
circuit on 14ga because the compressor is only half of that load. But if the
circuit is 100' or more, I'd go to 12ga (perhaps even leaving the breakers at 15A).
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
twiedeman
agree that 240v dedicated seems like the way to go. Concerning your question
about the source, your sub-panel is as good a source as any,especially if it
is closer.Is it a 100a sub? Make sure it isn't maxed out, & that you can add
the extra dedicated circuit.
Todd
Chris Lewis
> If it were me, I'd definately go to 240V. But I would consider leaving it a 15A
> circuit on 14ga because the compressor is only half of that load. But if the
> circuit is 100' or more, I'd go to 12ga (perhaps even leaving the breakers at 15A).
I just reread part of this thread, and realize that the existing circuit
is 20A/120V. I'd still switch to 240V. 15A breakers, unless you intend
on sharing this circuit with other 240V equipment ("one man shop" rules
assume you'll be only running one tool at a time. Give provision for,
say, a 3HP tablesaw, and go to 20A if you think you might need it for
something else too.)
12ga if you're leaving the circuit at 15A and the circuit is going to be
longer than about 40-50'.
Robert
////I need to know what size capacitor is used on this . I have the doerr 2hp
120/240v 20.4a/10.2a 3470rpm motor l22132 on an old 2 post lift , however the
cap is damaged and un readable....any help is greatly appreciated
--
for full context, visit https://www.homeownershub.com/maintenance/electric-motor-question-517678-.htm
gfre...@aol.com
<caedfaa9ed1216d60ef...@example.com> wrote:
>replying to Banister Stairwell, Robert wrote:
>////I need to know what size capacitor is used on this . I have the doerr 2hp
>120/240v 20.4a/10.2a 3470rpm motor l22132 on an old 2 post lift , however the
>cap is damaged and un readable....any help is greatly appreciated
something. Are you sure it is not on the motor label?
If there is only one capacitor it is the start capacitor and they are
not really that critical. I would try something around 500-600 on a
120v motor and 130-140 on a 240v motor. Run capacitors have to be more
closely matched.
Pasieka
any chance any of you guys have a 5 HP does motor that matches mine? need your help with RUN capacitor value
https://www.homeownershub.com/img/2qor
https://www.homeownershub.com/img/2qot
https://www.homeownershub.com/img/2qov
https://www.homeownershub.com/img/2qox
https://www.homeownershub.com/img/2qoz
--
For full context, visit https://www.homeownershub.com/maintenance/electric-motor-question-517678-.htm
bud--
> think reactive power and power factors all come into the picture, but i
> cannot say I remember enough to comment, but have a feeling the
> Inductive load of the motor is more favorably billed in terms of
> realized power when you have it wired across two legs of a single phase
> instead of a one leg... i believe the neutral current measured actually
> approaches zero in the 240 wired config and is significantly more in the
> 120 configuration... the neutral gets connected to ground at the main
> bonding jumper and goes back to the electric company with no credit to
> the home owner....
Utility meters accurately measure actual power. They are not confused by
inductance (reactive 'power'), neutrals or 120 vs. 240 connection.
Neutral:
https://en.wikipedia.org/wiki/Blondel%27s_theorem
N conductors: H N H
N-1 conductors: H H
Note that a start cap can't be used as a run cap. A run cap is much
higher quality, larger, and should be lower value.