Variable Frequency Drive

[rusty]

It is 240 volt. If you talk to the guys at Wrico they say the generator will not start the 5 HP motor. It has been starting it for 10 years now it won't. The generator has 121 on both legs and 242 across the legs and runs at 61 Hz. when you try to start the motor it will drop to 80 volts. The inrush talk is making more sense to me. Do capacitors get weak I think Clifford hinted at this.

Thank You Wayne

[Geoff]

When my generator wasn't​ running right it would start and put out full power but when I tried to run more than one roof air it would kill the engine.  As mentioned before, it turned out the injectors needed to be rebuilt. After that I could run three airs, the electric water heater, and everything 120v and the generator would handle it all.


--Geoff

[dtcerrato]

Capacitors do get weak, and yes I think Cliff hit it with the motor start capacitor. That's a cheap repair, even if it goes beyond that...

[luvrbus]

Wayne, you can up the voltage with a different starting capacitor it doesn't have to be as same as the old one talk to your supplier and they can fix you up   

[chessie4905]

How about replacing the capacitors with new and see if that doesn't fix it. They should have the specs marked on them.

[B_K]

Maybe the generator finally decided it wasn't going to do what it wasn't supposed to do anymore!

No all kidding a side, I tend to thing Geoff is on the right track if it starts fine off the shore power but not the genny!
  BK   

[Oonrahnjay]

When my generator wasn't​ running right it would start and put out full power but when I tried to run more than one roof air it would kill the engine.  As mentioned before, it turned out the injectors needed to be rebuilt. After that I could run three airs, the electric water heater, and everything 120v and the generator would handle it all.

--Geoff

     That's interesting to know, Geoff, and it seems to me to be something that everyone should keep in mind when considering any "weak generator" problem.  Does the same thing apply to the generator head?  I'd think that if you had windings or brushes or similar parts that were causing less power from one leg, it would work the same way -- is that right?

[Geoff]

    That's interesting to know, Geoff, and it seems to me to be something that everyone should keep in mind when considering any "weak generator" problem.  Does the same thing apply to the generator head?  I'd think that if you had windings or brushes or similar parts that were causing less power from one leg, it would work the same way -- is that right?

I have had generators that simply quit charging and the engine ran okay, and I bought a portable gas 7kW from Costco that would only put out enough power to run a 100 watt light bulb but not anything like my 240v hot pressure washer.  The engine would run but the pressure washer would just humm.  I took it back and got another generator and it ran the pressure washer just fine.  You could hear the generator bog down when the pressure washer was tuned on but it held the load.

Now with my 8kW diesel genet for the bus, when a load would kill the engine I called the company that built it and the owner told me to run through the generator head troubleshooting procedures in the book to test the generator head.  I did every one and even had to buy a new test meter to do it.  The owner of the generator company thought it was the generator head that was killing the engine, but all ny testing showed the generator head was good.  So that is when I started checking out the engine and decided to pull the return line from the injectors off to see if I had good flow.  I had good flow, but the diesel fuel coming out was black!

So I pulled the injectors and saw a lot of carbon build up on the tips.  The air cleaner was also black.  So I realized I had the air intake too close to the engine exhaust and the engine was pulling in the smoke from a clogged air filter.  I simply replaced the injector tips and air cleaner, put it back together and my low power problem was fixed.

So this does not tell me if a bad generator head will slow down an engine, but the owner of the genset company thought it was the problem, so based on his extensive experience I have to say it is possible.  But it hasn't happened to me.  Rusty has not indicated he has done any testing of his 13kW genset, whether it bogs down when it won't start the 5hp motor or if it keeps running the same .  If it keeps running the same I would guess he has something wrong with his generator head.  A very simple test is to take the bus to a shop that works on generators hand have them do a load test

--Geoff

[rusty]

Geoff has some valid points. Everything else that is on the generator works fine ( two 13000 roof airs 2800 inverter heating element in the water heater. I have heard every word you said. I now have two things to look at the generator and the motor. I think I will start with the motor. If that is not it then I will look at the generator but will do one at a time so I know what the problem is.

Now back to my original question Does anyone know if a variable frequency drive will help with the lack of inrush of power from the generator.

Thank You Wayne

[Lin]

I do not know anything about your drive question.  Just wondering, are the references to upgrading the capacitor the same as installing a hard start kit?

[Oonrahnjay]

I do not know anything about your drive question. 

    I'm also baffled ... (yeah, not unusual).  Is your 5-Hp motor a 120V, single phase motor?  Also, the plain conversion says that 13Kv is approx. equivalent to 17-Hp; if the 13Kv generator is working anything like properly, why wouldn't it start and run a 5-Hp motor?   
    But to your question about VFDs, here's what I found first:

https://en.wikipedia.org/wiki/Variable-frequency_drive

    It seems to me that these are devices used to *lower* the power to a motor once it's running (to save juice) and not a device to "supercharge" power so as to start an overloaded motor.
    And I don't understand your automatic-powerup sequence.  Do you mean that you're running air conditioners plus whatever the inverter will pull as charging power when you're trying to start your leveler motor?  If so, I'd guess that changing that would be a lot more useful than adding some hi-tech electronic control to the leveler motor.  But, don't pay much attention to me, I'm baffled!

[Emcemv]

Didn't see that anyone answered one of your original questions, using a variable frequency drive will definatly solve your motor starting problem, it eliminates the high inrush current of the motor.

[sixtyseven]

If you talk to the guys at Wrico they say the generator will not start the 5 HP motor.

Thank You Wayne

Did the guys at Wrico say why the generator will not start the 5 HP motor ?   That just doesn't sound right.   
Everything I read here points to the 5 hp motor as the problem, not the generator.   Did you check the amps at startup ?   If the volts drop to 80, that means the amps must be way high.  You should have about 48 amps at startup and around 23 running. (not counting the other loads) I see no reason a 13kw shouldn't handle that, even with the extra loads it should be ok.   I agree that checking the capacitor would be the first place to start.  Don't forget to discharge it first

[Geoff]

Okay.  In my previous post I told how a Costco 7kW genset wouldn't run my hot pressure washer and it was a defective generator head.  I looked at my pressure washer and it has a 5hp motor that pulls 22 amps@240 bolts.  So a 13kW generator should have no problem.  I don't know who you talked to at Wrico that said a 13kw wouldn't start a 5hp motor but it had to be some kind of mis-communication.

--Geoff

[rusty]

Thank You Bruce. I will let all know what I find

Wayne