Variable Frequency Drive

[rusty]

I have a 5 hp motor that powers the hydraulic leveling system on my Eagle. I have a 13 KW generator to power the coach. I know that in theory the generator is not big enough to start the motor but for 11 years it has. A couple of years ago I changed out my trace inverter with a magnum and the best I can remember that is when the 5 HP motor became harder to get started and has gotten worse over time. When I start the generator I have a timed relay to let the generator come up to full power before things turn on. Then 2 smaller ( one of them is 1 hp ) cooling fans come on, The inverter comes on and starts charging and if the system is cool the electric element in the Aqua Hot comes on. Then I start the leveling system. The electronic gurus at this point are have a heart attack. I think I can use a smaller ( 3 HP ) motor to power the leveling system or for less bucks I can put a variable frequency drive in the system. Will that help the starting problem? Or what else can I do without tearing the bus apart and start over. I don't want to do this as I still building the second conversion.

Thank You Wayne

[luvrbus]

Wayne give thought to changing the motor over to DC current a 5hp starter motor is easy to find

[Geoff]

I would think a 13k generator has plenty of power to start a 5 HP motor.  Maybe you should change your start up procedure from using the inverter and just start the generator and once you are level shut the genset down.  The inverter then takes over.  Or am I missing something?

--Geoff

[rusty]

Geoff, From what I can figure out is when the motor starts there is not ( for lack of better words ) enough in rush of power to get the motor started when on the generator. When on shore power it starts fine.  I have the system torn apart at this time and can't test your theory. Does anyone know if I can put larger capacitor on the motor to help this. Thanks Clifford but that means a lot more work and and want a easier fix .

Thank You Wayne

[luvrbus]

I would give the larger starting capacitor a shot then,if you have the start/run capacitor you can rewire it to a 2 capacitor system fairly easy,electric motors are older people they get weak and need a little extra kick   

[scanzel]

Just curious but what leveling system requires a 5hp ac motor, is this a home built leveling system ?

[uncle ned]

Rusty    Huggy has hydraulic levelers on her and I have no problems using them on a 10 k generator.

What do you have on that IGGLE.

uncle ned

PS are you coming to NC this summer and do i need to get some more spring water.

[rusty]

Steve It is a home built system made from parts of an old bridge deck finish machine I had laying around the cylinders are from other pieces of equipment I had. I tend to over build things. The bridge deck finish machine used a 25 horse motor so I guessed a 5 horse would work and it does except now the generator does not like it.

Ned. We will be at NC if I have to use railroad jacks to level the IGGLE. I will pass on the Spring Water. The doc says if it tastes good spit it out and that includes spring water. If I knew I was going to live this long I would have taken better care of myself. See you in a couple months

Wayne

[Geoff]

If the 5hp motor starts on shore power I would say something is wrong with the genset.  My 8kw genset was having power issues​ and after going through the entire book trouble shooting procedure it turned out to be clogged injector tips from sucking exhaust smoke into the air intake.  That was not in the book.

--Geoff

[chessie4905]

You could probably get a one hp motor motor to do the job. Just would take longer to level. Is your system trying to draw the extra from your battery pack? Maybe batteries are getting weak.

[Geoff]

I have an oil filter crusher that handles full size truck and bus oil filters​. It came with a 1hp motor and turns a 22 ton hydraulic pump.  The motor quit, so I bought a 1.5hp motor from Harbor Freight.  It would not turn the pump.  Took it back and got the 2hp.  It wasn't strong enough either. Both 120v.
So I took that one back and got the 3hp 240v motor.  That one worked!  My point? American vs Chinese.

--Geoff

[Iceni John]

My little 3500W emergencies-only generator won't comfortably start my on-board air compressor once it's at pressure if I plug it straight in to the generator.   If however I connect it through a 100 ft 12-ga extension cord it will start better.   Figure that one out!   I remember reading about something like that on the NAWS forum, so I tried it and it works.   Don't ask me why.   I think it's something to do with Power Factor  -  my compressor has a lousy PF (like most capacitor-start Chinese motors), somewhere about 0.6-something according to my Kill-A-Watt meter.   I wish I better understood all that EE stuff!

John

[dtcerrato]

I think an added capacitor is the answer. It will help to absorb the inrush of current at start up.
I believe the added 12 ga. extension cord is doing something parallel but using resistance to absorb inrush instead of capacitance. I'm not an electrical engineer but it sure sounded good IMO... :-)

[eagle19952]

I would give the larger starting capacitor a shot then, if you have the start/run capacitor you can rewire it to a 2 capacitor system fairly easy, electric motors are older people they get weak and need a little extra kick   

they get harder to start if it is cold too or a load/partial load is on it. is there a relief valve?
should be a tag, FLA and LRA...Locked rotor and full load amps...you can tell how old or worn out it is with a clamp on amp meter.
for the duty cycle, a DC motor works. seems old Ford starter motors and relay are what we built snow plow hydraulics out of.

[sixtyseven]

I would think a 13k generator has plenty of power to start a 5 HP motor.  Maybe you should change your start up procedure from using the inverter and just start the generator and once you are level shut the genset down.  The inverter then takes over.  Or am I missing something?

--Geoff

Geoff,   I don't think you're missing anything, I think Wayne is.    He forgot to tell us what voltage his 5 hp motor is.   If it's 240 volt then his 13 kw should start it without missing a beat, but if its 120 volt, that would put a serious strain on things.   How-bout-it Wayne, what voltage we talkin ?