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Re: (ET) E20 lacking power



You have something seriously screwed in your field current. Field should be about battery power; it should never drop that low on speeds 7 and 8; that's basically using the compensation windings as a field.

Chris

Markus Lorch wrote:
Thanks for all your replies.
Based on Steve's suggestions I did some measurements
this evening. The following table shows the voltages I measured in the different speeds with the transmission in neutral. I later measured under load and the only major difference was the armature voltage that caved in on heavy loads mainly in speeds 1-3, which was expected.

Speed    Armature     Field    Battery
1         29.8        34.5      37.5
2         30.6        34.4      37.3
3         31.6        34.4      37.3
4         33.6        33.4      37.0
5         35.5        33.2      37.0
6         35.5        11.7      36.7
7         34.7         8.1      36.7
8         34.4         5.5      36.5

I was puzzling why the field current is lower
than the battery. The voltage drop from the diodes shouldn't be that much (0.7V, right?). So maybe I should revisit that circuit to make sure I provide a high enough voltage to the field.
The performance of the tractor while driving it around
seemed a bit better than yesterday. Maybe the field
connector wasn't seated right and had a high resistance.
Running in D2 is now mostly in the yellow area
except when going up inclines.
Markus


Also poor motor performance and large currents is usually

associated
with a weak (or missing) field. You may want to hook up the

voltmeter
across the field terminals and check that it's 36V when in cruise mode - actually I guess anything below the field weakening setting should be 36V?.


These are good points. Too low a field could really be the problem and
I haven't measured the field voltage after I fixed the diodes, so I think this is a good thing to check.
Thanks

Markus


SteveS
E20



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