Mowing Elec problem on 1850 (slope mower)

[wasabi]

Hey folks,

Long time between visits for me. life is very full.

Having a weird electrical problem with my 1850. 0nly 300 hours on the unit.
Replaced the circuit breaker with an auto store 15amp (old one was taped together to bypass - not be me )
Now she starts fine and will run for a minute or two and then the new CB trips, shutting her down.

thoughts?

 

[MossRoad]

Long time no hear!

Got a schematic?

 

[woodlandfarms]

So, are you referring to the resetable one on the dash? If so, first and foremost it is 20amp. There are two others on your machine, one 30 amp and one 50 amp. I can provide you a schematic. When does this happen? When you mow? So the solenoid on the PTO valve is a huge power draw. Have you ever taken off the coil off the PTO solenoid? You should. Then run some steel wool around the valve itself and inside the magnet.

Also, you could have a short. Its not uncommon on the terrible wiring in the PT. Usually it happens under the dash in or in the rear box. a "hair" off the wire connections will touch somehting and bring it to a stop. Oh, I have had numerous issues with the wiring at the starter solenoid.

Finally no guarantee your circuit breaker is any good. I have had that happen where the breaker was mediocre an would just release.

 

[SpringHollow]

As it happens, I have to track down what is wrong with the wiring for my starter solenoid. I have not found the time so I just keep jumping the solenoid. Pretty stupid, I know but that is the way it goes lately. I have found mice love the dash on my PT1850 and cause 3/4's of the electrical problems. They must be mutant mice because moth balls do not seen to deter them. The most interesting was when mice made a nest inside the muffler. Picture the man being shot out of a cannon at a circus!

Ken

 

[woodlandfarms]

I have an issue with my starting as well that I have yet to resolve. sometimes you turn the key, things click but hte starter does not turn over. Not sure where the issue is. Going to have to track it down.

 

[wasabi]

Thanks for the feedback. No schematic.

Will get a 20 amp breaker and see if that cures it. Wiring under dash looks ok
Also going to check the fuel solenoid. Terry seems to think that might be in play.

Oddly comforting to know this is happening to others. Misery loves company?

 

[CobyRupert]

Now she starts fine and will run for a minute or two and then the new CB trips, shutting her down.

You need to determine if a load on the system is overloading the breaker, or if a short in the system is tripping the breaker.

(Most) breakers either trip instantly when there is a short circuit (= lots of current, say >600% of the breaker rating), or trip at some (longer) time duration depending on how much they are overloaded (example: lets say it takes 5 minutes to trip when current is 125% of their rating, 3 minutes at 150%, 20 seconds at 300%, etc..)

So...it runs for a minute or two and then trips.
During this minute are you turning on a load (e.g. the PTO solenoid) that may be overloading the breaker to where it trips after a minute?
Or are you traveling over bumps, or have other vibrations that may jiggle a wire and cause a short?

 

[wasabi]

Hey Coby,

Doesn't seem to matter whether under load or not. Runs for about a minute whether in motion or sitting still....then CB pops and she shuts down.

Have tried every which way I can with same results. Haven't put a stop watch on it but I'd bet run time is consistent within ten seconds.

 

[joecoin]

Breakers trip when they get too hot. They get too hot when they draw too much current. As noted, a short (or partial short) will cause that condition.

Since it works for a little while, I'd guess the 20 amp proper breaker may be the answer.

If not, I would get the meter out and start tracing wires with respect to ground.

 

[CobyRupert]

Thermal-magnetic breakers have two mechanisms for tripping.
On a overload (lets say anywhere from 100% to 600% of its current rating) , the heat (thermal) will trip it, the time duration that it allows this current to flow until it trips will be inversely proportional to how much it is overloaded (and how fast the heat builds up.) More current = less time.
On a short circuit (say current >600% of breaker's rating), the magnetic forces around the surge current will magnetically trip the breaker very quickly (almost instantly, almost independent of time).

The bad news when diagnosing if its a short or an overload, is that one can get a short circuit (to frame), but the short circuit current flows through poor resistance (maybe it shorts to paint, or dirt covered metal, etc..) and this limits the current to below the instant magnetic trip level, and it takes a while for the breaker to trip thermally.