Motor for vacuume pump problem

[SadSams]

We finally got our remote building all setup for down in the bush. We thought we better try the vac pump with the generator before we pull it into the woods. Now let me start by saying, we did hook it up to the 230v/30a breaker in the sugar shack and it worked great. So now, we tried it with the generator and oh oh whats wrong? It starts but, not up to speed for sure. Motor started to get warm so we shut it off. This generator should be enough. Its a briggs 15hp and its rated at 8000 watts/ 13,500 starting watts. The motor is a 3hp, 230v and 17amps. I'm not an electrican but if I remember right don't you mulitply volts x amps? It should pull 3910watts well in range. Neither one of us had a volt meter on hand so I brought the generator back home with me. I checked it this morning and its putting out 250volts. Any thoughts guys.

[maple flats]

Check your connections. On the flip side, you will be much more efficient and dependable if you change out the electric motor for a gas engine. I have 2 pumps, both Alamo rotary vane pumps. I removed the 3 HP electric motors and put 200 CC Honda motors (6.5 HP?) Make a motor mount that can pivot for belt tension, but use an adjustable bolt for a leg to regulate the tension. Then get a larger fuel tank and hook to that. I bought some generator replacement tanks from Surplus Center @ $18.99 ea. They hold 4.5 gal which will run the motor at least 18 hrs, maybe up to 24 hrs, depending on the throttle setting you use. I go just about 1800-2000 rpm. Don't mount the tank much higher than the original and it will work well. To start it I tilt the motor slightly to loosten the belt and it starts first pull, then I set the motor back to drive the pump. I only shut down to check/change the oil or if it freezes and stops sap flow. For more efficient than running 15 horses to convert the rotary energy to electric and back to rotary power again. Also, the motor on the pump can be slowed as needed, the generator will be full speed and fuel use all the time.

[SadSams]

That all sounds good Dave but, I need the generator to operate the pump (230volt) mounted on the bottom of the releaser. This is a milk house system. It has the probes inside the releaser so when full it closes a set of contacts and gives power to the pump. Hmmm, I can see a new system in my future.
Thanks for the input Dave.

[maple flats]

OK, check your voltages. Use a good multimeter, set it on 600V setting and carefully take a reading with the motor turned on. Use the contacts where the wire connects in the motor. If it is a terminal post get the reading off the post, not the input wire. This will verify the actual voltage getting to the motor. You likely have a bad connection. A generator can generally start a motor properly up to about 75% of rated load as long as the surge does not exceed the generator's rating. If it does not show starting amps you need an ammeter or an electrician with one. If it shows starting amps, multiply that x your voltage (use actual voltage, not rated voltage.) You need the actual voltage at the time the motor starts. Good luck. Since you will now have 2 motors running at the same time, you must figure the bigger one needs to start while the lesser one is running. Be careful testing and if you are not positive how to do it safely, get an electrician.

[SadSams]

I think your right Dave, connection problem. Like I said, we didn't have a meter with this weekend to do a good check out. Now that I'm home i've got all kinds of test meters in the work truck. Wasn't going back up untill new years weekend but its bugging the heck out of me. I may look for a slow spot in the work schedule this week and head up (100 miles) door to door. I'll let you know.

[Housewright]

Induction motors are very sensitive to cycles. cycles are directly related to engine rpm of the generator. So as it tries to start your motor the load may cause the engine rpm to drop. Which causes the motor to demand more amps. Which causes the rpms to drop more..... Generators do not like big induction motors and 3 horse power may be too much for your generator. This is why you see a lot of gas powered compressors on construction sites. Brush type motors are much less sensitive to cycles.

[oneoldsap]

You might check your wire connections at the motor for corrosion . DC motors slow down when voltage is low , AC motors cook themselves when voltage is low . Gas powered vac pumps are a PITA , but a must in some situations . BTDT

[Brent]

Did you try the vac pump at home on your household current before you took it to the bush ?
Two possibilities on the motor itself
1) the capacitors are dead
2) the centrifical switch is sticking and not switching to high speed winding when the
revs get past a few hundred rpm

[wiam]

He said it worked ok at sugarhouse. I think his generator has issues.

[SadSams]

Some of you guys don't read everything that I explained in my first discription. Sorry for that but, I think my problem is resolved. The motor was not a capasitor start type. It wasn't quite getting up to speed to kick it into run winding. Almost, but not quite. So, I stopped by Graingers and bought a new motor. 3hp, cap. start. Also just for a little extra help in starting I picked up a 1'' smaller pulley for the motor side and 2 shorter belts. I'm confident this is going to solve it. When I get back up north next weekend we'll try it out. I'll report in a week or so.

[Brent]

sounds promising. I missed the part where you said it ran of utility power.

[maple flats]

I still think it was a connection problem. You have 15000 watts and only need about 1/4 that. Should be good, but a capacitor motor will likely be better anyways. Good luck.
Dave

[SadSams]

Hears the latest. I put on the new motor that I picked up at Graingers and I have the same problem. So ok lets try something else. I took off the belts and started the motor it runs good. So then I carefully but not recommended slipped the belt on. This works. It pulled 17'' vac the motor was at full load amps. So it just wont start under load with the generator. I'm going to fabricate a pivot to loosen the belts at startup and be able to tighten after startup. Its just one more thing to do each morning but it could be worse. Jumping off the subject a bit. Its going to be 40 degrees today in central minnesota. I'm going to take advantage of that and hopefully finish the pipeline today.

[lastwoodsman]

Sounds like you are getting there.
Good to hear

Woodsman