Generator producing excess AC voltage

[GrahamW]

Hi

I recently bought a boat with an out of commission "Gemini"230V AC genset on board.

It was manufactured by a company in Germany called HFL using a 3000 RPM Mitsubishi L2e engine coupled to a Markon BL105 brushless self exciting capacitor controlled alternator.

With a bit of care and attention the engine is now running fine, but according to the amp meter it is producing 300V. Mastevolt charger will not run, presumably because it senses that the input voltage coming from the generator is too high.

I´ll be grateful for any suggestions as to what the problem might be - faulty capacitor : engine running at too high RPM : ???

Many thanks,

Graham

[svBeBe]

Most generators have an actuator which controls RPM. It adds throttle as load is added to maintain a constant RPM so that you have constant voltage.

My first guess is that the actuator is either jammed, not connected, or not working.

I hope this helps you, let me know.

Bill
BeBe

[GrahamW]

Hi Bill,

Thanks for the reply.

As far as I am aware there is no mechanism to vary the throttle setting. In fact the lever where a control cable would connect is fixed in position permanently.

Graham

[svBeBe]

Graham,

There has to be. How else would the generator get additional fuel as the load increases.

Look further. I have not worked on one of these, but every other generator I have been up close and personal with does.

Bill

[DotDun]

You need to measure the frequency. Is it 50hz ?

[a64pilot]

I'd first verify the frequency, my Fluke multimeter will do this, I assume it's not un-common, if the RPM is high, then so will the frequency as only thing that changes frequency is RPM. Once you verify RPM by checking frequency, if the voltage is still high, then I'd assume a voltage regulation problem

[svBeBe]

Graham,

Go here Marriner High Speed Gensets | HFL

Look at the features. You will see "constant speed governing."

This is what is not working, broken or missing.

[svBeBe]

Graham,

Go here Marriner High Speed Gensets | HFL

Look at the features. You will see "constant speed governing."

This is what is not working, broken or missing.

Bill

[colemj]

Changing the engine rpm on that Markon head will mainly effect the frequency, and only minimally change the voltage. You should definitely check the frequency and make sure it is within specs before going further.

For voltage out of range, check to make sure the run capacitor is the correct one. I think you should have a 40uF cap on that Markon, but I don't know that for sure. Your manual should say. Also check the wiring and connections between the run capacitor and the excitation circuit on the head - these Markon heads are not rugged and use some pretty lightweight wiring and connectors.

Mark

[Moody46CC]

I have the same engine for my Mastervolt Genset, but it is a US set up, 60MHz, 120V AC at 3600 rpm. The 50MHz European models run at 3000 rpm. The engine used to overheat intermittently, but I think I cured that by back-flushing the cooling system this spring--flushed out some chunks of broken impeller vanes. Has not overheated since.

But now it "overloads" and then shuts down automatically according to the LED idiot lights on the remote control panel. It produces 120V according to my voltmeter On the boat instrument panel) and it produces up to 25-30 amps (again, on the boat instrument panel) depending on the load, but after about 30 minutes the red LED idiot "overload" light comes on and then it shuts down automatically. In fact, it does this regularly with and without any load on it. I'll fire it up and let it run w/o any draw, and it shuts down after about 30 minutes. The rather minimal trouble shooting section of the equally minimal operators manual gives capacitors as the first likely cause, and not being an electrician, I'm having the dealer look at it late next week. Will advise this group what happens.

What is also interesting is that the LED idiot light panel has LEDs for percentage of load on the generator, e.g., 25%, 50%, 75% and "overload." None of the numbers except overload have ever lit up regardless of draw. So that board could be bad as well.

[GrahamW]

Hi and thanks to all who have replied so far.

It seems like I need to gather some more data such as frequency, RPM etc in order for people to diagnose further so I will do that and come back with the results, hopefully next week.

Graham

[Sailmonkey]

Originally Posted by svBeBe

Graham,

There has to be. How else would the generator get additional fuel as the load increases.

Look further. I have not worked on one of these, but every other generator I have been up close and personal with does.

Bill

Many generators rely on the engines internal governor to meter fuel based on load. I've got both a 6kw based on Kubota and a 35kw cummins based engine that have the external fuel rack adjustment fixed in place to maintain 1800 rpm. The internal centrifugal governors maintain a fairly accurate speed regardless of load.


Sent from my iPhone using Cruisers Sailing Forum

[ex-12m-guy]

Sounds like you may have a bad AVR (automatic voltage regulator)
board.

Download the manual here for more details

hardydiesel.com/generator-ends/dl/markon-generator-manual...

The 3000 rpm engine means the genset is 50 HZ with the standard
European voltage of 220 v. (A 60 HZ 120/240 unit runs at 3600 rpm.)

The speed of an engine driving an AC alternator has little to do with the voltage. The speed determines the frequency of the AC power. The voltage is regulated by the AVR board as long as the engine governor is able to keep the rpm on or near spec.

[GrahamW]

Thanks ex 12M guy,

Can you please try posting that link again - I could not get it to work. And though I did go to the Generator Ends section of the Hardy site I could not find a reference to the Markon...

Graham

[CdS2 Roland]

Hello,
I have a Mastervolt Whisper 6, running with a Mitsubishi diesel engine. It looks be regulated the same way as yours.
1) RPM controls the frenquency (higher RPM = higher Hz) in Europe the frenquency is 50Hz


2) The capacitors controls the the voltage. Your problem is probabely due to the faulty capacitor(s).


You have to know that these parts must be changed from time to time. Depending on load, temperature, etc... On Whisper 6 they were originaly mounted inside the genset cocoon. I put them outside in an easy accessible place. Mastervolt changed capacitors from class B to class C.


Maximum voltage accepted by Mastervolt charger is 265 volts.


Good luck.