Capacitors to smooth out load?

[Clarksonguam]

Does anyone know anything about the possibility of using a bank of capacitors to smooth out the load (surge) from our washing machine? It would seem possible but would require knowledge that is beyong my knowledge. Any assistance would be appreciated.

[mike90045]

Capacitors smooth out DC power.     There are some AC  Motor Start and Motor Run capacitors, but they are either already designed into the motor, or you need special knowledge to add / fine tune them, not regular handyman stuff.    And a cap can be added to the rectified DC in a field coil in an alternator, but that's not what you asked.

Starting surge, you need a beefy inverter or genset to be able to supply it.

[Ronmar]

What mike said...

You could probably buffer the large washing machine motor startup load in 2 ways.

1.  Setup a grid tied inverter and battery with the output voltage level/cutin point just slightly below that of the line load.  As the washing machine starts to draw current, the voltage will drop, and the grid tied inverter will feed current to attempt to maintain it's rated output.

2.  An induction motor with a flywheel across the line.  The induction motor will spin up the flywheel and maintain RPM with a steady state line voltage.  As the washing machine starts up, the inertia stored in the flywheel of the induction motor will attempt to maintain RPM, when the line voltage drops, causing the induction motor to give up energy back to the line like a generator...  There was a discussion that talked about this effect a while back.  Something about a bench grinder running when an air compressor started easing the startup load on the generator if I recall...

[getterdone]

i guess i may have the same problem.
my wife and i bought new washer and dryer. front load type[frigidaire] when we moved to our off grid place.
the washing machine works most of the time [if you turn on a light or force on our small electric hot water heater.]
the drier [propane] will light up but when it starts to tumble it shuts down.
it has never worked.
i even ran a separate wire to it and its own ground rod. didn't help.
so i got a $750.00 dryer that is useless.
i am powering every thing from a xantrex 4000/24v inverter with 1500amp hr batt bank.
i haven't tried the bench grinder method. but i will., oh and the inverter is a pure sign type.
looking at the manual for the appliances it said not for use with alternative energy.
well i didn't do my homework before i bought them.
is there any way to combat this growing problem. as more and more people choose to use alternative energy.
as old appliances wear out. how are we as off grid people trying to survive with a few modern conveniences going to make it.
i think its another government involvement to make it as difficult as possible for us as a people to survive on our own.

[rcavictim]

i guess i may have the same problem.
my wife and i bought new washer and dryer. front load type[frigidaire] when we moved to our off grid place.
the washing machine works most of the time [if you turn on a light or force on our small electric hot water heater.]
the drier [propane] will light up but when it starts to tumble it shuts down.
it has never worked.
i even ran a separate wire to it and its own ground rod. didn't help.
so i got a $750.00 dryer that is useless.
i am powering every thing from a xantrex 4000/24v inverter with 1500amp hr batt bank.
i haven't tried the bench grinder method. but i will., oh and the inverter is a pure sign type.
looking at the manual for the appliances it said not for use with alternative energy.
well i didn't do my homework before i bought them.
is there any way to combat this growing problem. as more and more people choose to use alternative energy.
as old appliances wear out. how are we as off grid people trying to survive with a few modern conveniences going to make it.
i think its another government involvement to make it as difficult as possible for us as a people to survive on our own.

I wonder if it is not a problem with the waveshape and voltage of the power you are providing for it but the fact tht there is no signal riding that power from Big Brother's secret domestic energy use spy known as a Smart Meter.  The drier cannot report your electricity usage to your non-existant smart meter so it is designed if it can't snitch, it can't work.  Could be!

[getterdone]

the voltage is there.
i dont have a way to check the wave form.
getting back to Clarksonguam's question; need to know what is your battery size is and wire size to inverter ,also size of inverter output is.
sorry for stealing your post.
some one here can answer your question. we need to know the size of your system.

[mbryner]

Is your inverter strong enough to handle the dryer motor's startup surge (amps)?  Dryers are pretty simple creatures, so starting w/ the bench grinder test sounds like a good idea.    We're off-grid and my wife's propane dryer works fine w/ Outback 3648 Inverters.

Marcus

[Ronmar]

Traditional driers use an induction motor and belt drive to rotate the drum.  Simple, and just needs enough startup current to spin-up the load.  If the voltage drops a little, the motor simply draws more current to compensate.  I think a lot of washers and dryers are now using direct drive motors and PWM to provide the mechanical energy.  This uses a switching power supply to provide the energy to the PWM controller.  If the supply voltage is shifting too much when the switching power supply is drawing from it, it may be exceeding some pre-programmed level which causes the shutdown.  That is probably where the not for alternative energy warning comes from.  Switching power supplies rely heavilly on the wave shape to draw energy from, and have to work real hard to do their job with a modified sinewave which is common from inverters.  Even a true sinewave inverter may have difficulty maintaining waveshape, unless it is oversized for the task/has a large reserve.  A quick test of this would be to go rent a portable generator large enough for the task and plug the dryer into it and see if it works with tha sinewave source.  I doubt it is a big brother thing as smart grid technology is not everywhere yet...

[Clarksonguam]

What mike said...

You could probably buffer the large washing machine motor startup load in 2 ways.

1.  Setup a grid tied inverter and battery with the output voltage level/cutin point just slightly below that of the line load.  As the washing machine starts to draw current, the voltage will drop, and the grid tied inverter will feed current to attempt to maintain it's rated output.

2.  An induction motor with a flywheel across the line.  The induction motor will spin up the flywheel and maintain RPM with a steady state line voltage.  As the washing machine starts up, the inertia stored in the flywheel of the induction motor will attempt to maintain RPM, when the line voltage drops, causing the induction motor to give up energy back to the line like a generator...  There was a discussion that talked about this effect a while back.  Something about a bench grinder running when an air compressor started easing the startup load on the generator if I recall...

All of this information is helpful. I'm not running batteries or an inverter yet (trying to figure out as many concerns prior to ordering remaining components). The induction motor idea might help, would two large ceiling fans have a similar effect, or maybe even the dryer motor.

[KeithO]

When pouring the slab for my main generator, I was running the concrete mixer from a cheep Chinese genset.
Its old induction type washing machine motor was having a hard time of it and started slowing and overheating, so I set up an elderly desk fan to cool it a bit.
As soon as the fan was plugged in the mixer motor accelerated to its proper speed.
I assumed it was power factor related in some way 

[rcavictim]

When pouring the slab for my main generator, I was running the concrete mixer from a cheep Chinese genset.
Its old induction type washing machine motor was having a hard time of it and started slowing and overheating, so I set up an elderly desk fan to cool it a bit.
As soon as the fan was plugged in the mixer motor accelerated to its proper speed.
I assumed it was power factor related in some way 

When I mix concrete I start slowing and overheating too!  Plugging in a fan might have helped when I was younger but probably won't help so much now. 

[KeithO]

 

[diesel]

Clarksonguam,
I would strongly recommend against adding capacitors to the system. Generator voltage regulators are not designed to drive a capacitive load and voltage fluctuations can result with resultant damage to equipment (fluctuations will be greatest where there is no resistive load).

getterdone,
Firstly, i would recommend trying the flywheel method as discussed above.
If the problem you are having are to do with harmonics (due to PWM) a capacitor would have a positive effect. The capacitor acts as a high-pass filter, smoothing out the waveform. It is similar to how a capacitor works in a DC system, providing stored energy at the point of the wave where it is required. As for the level of harmonics, and the amount of filtering required, I could only guess.

Check to make sure the xantrex can handle leading (capacitive) loads. I expect it should be able to.

High harmonic currents may cause capacitor heating and premature failure. Make sure you fuse them, and perhaps buy a higher voltage capacitor than you need.

[getterdone]

diesel, are you saying to put the capacitor at the washer and drier. i could make up a pannel to hold the capacitor's and plug directly to the pannel.
if so what size should i use? 5,10,35,50,.......microfarit
this morning my wife couldnt get the washer to work . i had her turn the a/c and then it worked fine. go figure.

[rcavictim]

'Cause we're all here to learn right!?    

Just a correction of a technical point made by Diesel.  A capacitor across a pair of wires (in shunt) looks like a lower and lower resistance to alternating current as the frequency goes up.  This makes a capacitor act like a Low Pass Filter, i.e the low frequencies pass or get through, not a High Pass Filter as incorrectly stated.  The acronyms LPF and HPF are in widespread use.

However, a capacitor in series with the load will in fact act as a HPF.  As the frequency goes down, less and less power will make it through to the load.

Pretty amazing eh!     Kinda like a thermos bottle.  It can keep cold things cold and hot things hot. There are no sensors or electronics in a thermos.  How does it know?