Talking about Generators...(sandbar)

[MikeP]

Every so often, our 16KW NL genny will almost come to a stop when one of the ac units cycle. I'm not sure which one causes it but it doesn't seem to cause it every time it cycles - just occasionally. Any idea what might cause a heavy elec load to be applied on starting sometimes but not always?

 

[Pascal]

What else is in? If a compressor kicks in with few other loads it will be fine but if you have something like 10kw of loads running then the genny may take a short time to recover

Check the meters and then turn the load on to see exactly if it depends on the existing load

Does voltage really dips to the point that the compressors will stop on low voltage?

Also check the filters if you haven't , both prim and sec

 

[Fanfare]

I have a Fluke Model 27 digital multimeter which has a min/max button. It reads the high and low voltage from the time the probes are plugged in until reset. Very useful for all kinds of electrical problems on board. It is also waterproof and explosion proof. The only thing it doesn't have is a frequency meter, but other Flukes do. www.myflukestore.com

 

[SKYCHENEY]

Mike,
You might ask that question on Steve's website.

http://marine-ac.com/

He's the resident expert on A/C units. I'd trust his advice over most anybody else on here as he works on this stuff for a living.

 

[MikeP]

Thanks Sky!

 

[MikeP]

Tried to join the ac site. After registering I got an email back with a link to activate but when I selected the link it took me to the a/c site but saying "Page not Found."

I tired it several times but the same thing occurred. Maybe they're having trouble with the server or something.

I searched through the ac forum (can read but can't post) but couldn't find anything with the same symptoms.

I've narrowed it down - it's only on the salon ac unit. The blower and sea pump comes on. After about 10 seconds there is a 70A draw for a fraction of a sec (assume it's when the compressor starts) but then current immediately drops to normal and the system works fine. When the spike occurs, any other elec item on ships service 2 drops out - TV, microwave, etc. Also, the inverter circuit trips over to batteries for about 3 seconds. So I'm trying to figure out what causes the huge spike in power draw for that compressor. Capacitors?

Note - originally I noticed it on the genny, hearing the genny slow but now I have found that the same thing happens with shore - there's just no genny engine to slow down!

 

[Pascal]

easier to replace the capacitors than the compressor!

that circuit breaker doesn't pop at 70amp? how old is the compressor?

 

[MikeP]

Compressor is the original 1980. The spike is too quick, I think, for the breaker to react and it may not really be 70A. THe needle at the ships panel is up and down almost instantly and since it's a needle, the inertia carries it probably well beyond the actual amperage reading.

I probably won't fool with it now - I'm only here for a couple of days to winterize but planning for spring...

 

[Pascal]

i'd look at the capacitors first, they're pretty cheap... maybe you can swap them with another set from another unit.

it's normal for amps to spike on start up, but with a compressor that size (i'm guessing 16k?) a a 16kw genset should recover before stuffs comes off line.

that said, on the boat i run, when the saloon 48k btu compressor kicks in, neither NL20 can keep voltage high enough when the watermaker is running and usually the WM shuts down on low voltage.]

and that's a new 48k compressor...

 

[spcoolin]

Tried to join the ac site. After registering I got an email back with a link to activate but when I selected the link it took me to the a/c site but saying "Page not Found."

I tired it several times but the same thing occurred. Maybe they're having trouble with the server or something.

I searched through the ac forum (can read but can't post) but couldn't find anything with the same symptoms.

I've narrowed it down - it's only on the salon ac unit. The blower and sea pump comes on. After about 10 seconds there is a 70A draw for a fraction of a sec (assume it's when the compressor starts) but then current immediately drops to normal and the system works fine. When the spike occurs, any other elec item on ships service 2 drops out - TV, microwave, etc. Also, the inverter circuit trips over to batteries for about 3 seconds. So I'm trying to figure out what causes the huge spike in power draw for that compressor. Capacitors?

Note - originally I noticed it on the genny, hearing the genny slow but now I have found that the same thing happens with shore - there's just no genny engine to slow down!

Mike...The way that works is I need to approve you....I've had some bad joiners lately...Anyway...You are approved now...Go ahead & sign in if you like...

Steve~

 

[REBrueckner]

Sp is the guy to check with...could be a capacitor or a loose connection to one or an overhcharge of refrigerant, even a failing motor armature......just guesses...much better to check with the guy who really knows likely causes from practical experience....

 

[spcoolin]

Tried to join the ac site. After registering I got an email back with a link to activate but when I selected the link it took me to the a/c site but saying "Page not Found."

I tired it several times but the same thing occurred. Maybe they're having trouble with the server or something.

I searched through the ac forum (can read but can't post) but couldn't find anything with the same symptoms.

I've narrowed it down - it's only on the salon ac unit. The blower and sea pump comes on. After about 10 seconds there is a 70A draw for a fraction of a sec (assume it's when the compressor starts) but then current immediately drops to normal and the system works fine. When the spike occurs, any other elec item on ships service 2 drops out - TV, microwave, etc. Also, the inverter circuit trips over to batteries for about 3 seconds. So I'm trying to figure out what causes the huge spike in power draw for that compressor. Capacitors?

Note - originally I noticed it on the genny, hearing the genny slow but now I have found that the same thing happens with shore - there's just no genny engine to slow down!

Mike...The way that works is I need to approve you....I've had some bad joiners lately...Anyway...You are approved now...Go ahead & sign in if you like...

Steve~

Since you say it does it on shore too...Yes we can rule out the generator...

Need to know:

Does the compressor actually start & run, or do you think it's tripping it's overload...Meaning, Do you hear a "plink" or "pop" type noise at the unit, right before the amperage drops...If so, it seems you may have a bad compressor as 74 amps is the Locked Rotor Amp draw rating of a 16K compressor...

If after the amps drop...You can then feel heat or cool (depending on if the unit is in hear or cool mode) in the water coil...Then the compressor is running & it at least has some freon...

Yes I would check the capacitors...Easy to open the box in between the service valves & check for burnt connections, or for an expanded run cap (silver one) or a blown start cap (black one)...The start cap will spew black gunk everywhere when it fails, and it's failure is usually due to a failed start relay, so you will need to change that too...

Pascal...

This will solve your problem with that 48K (4 ton) system...
http://marine-ac.com/2010/11/08/marine-ac-compressor-smartstart-soft-start-hard-start-assist-2/

You remove the start relay & capacitor & replace it with the SmartStart...
I have a 110 Broward customer that has three single phase 4 ton chillers that was having the same type problems as you mention...Installed the SmartStarts and the problems all went away...

Steve~

 

[Pascal]

thks steve!

i'll look it up on your site.. it's not a major issue since what i often do in the evening is run the second genny when we're running the WM and a lot of other things like dryer, cooking, etc... but that might be a solution

looks like it's up to 16k and 120v only... dont' see anything bigger, is that the only size? that compressor is 48k and 240v

 

[MikeP]

Heading over to the sp site - more monitoring shows symptoms are not exactly as I had posted previously anyway..

 

[Angela]

Mike, I had that same exact symptom on my 1980 condensing unit (still running strong...knock, knock) that runs the salon/galley. It began after the installation of new air handlers...long story short - it was overcharged. Adjusted the pressures and worked nicely ever since. Not to say that that's your particular problem - spcoolin is the one to tell you what's wrong - but that was my problem with that same set of symptoms. Like others said, it could be something else, too.

 

[spcoolin]

thks steve!

i'll look it up on your site.. it's not a major issue since what i often do in the evening is run the second genny when we're running the WM and a lot of other things like dryer, cooking, etc... but that might be a solution

looks like it's up to 16k and 120v only... dont' see anything bigger, is that the only size? that compressor is 48k and 240v

Yes it's a differing part # for the larger ones that I don't have listed yet....But they are are all the same dimensions & price...Just let me know what size unit it's needed for...

Steve~