? about ST head with AVR

[tinkerer]

Hello. I have a ST head ordered from Tom at CGG that will have an AVR installed. I am coupling this to my SC yanmar. I was wondering if it would damage, fry, whatever you wanna call it, the AVR if the head was run below 1800 RPM "without" a load? The reason I ask this is I would like to be able to let my engine warm up at an idle before it runs at "generating" rpm.  Once the engine is warmed up, I would open the throttle and then apply the load to the generator. What do you think?

Thanks!
Ben

[rcavictim]

Hello. I have a ST head ordered from Tom at CGG that will have an AVR installed. I am coupling this to my SC yanmar. I was wondering if it would damage, fry, whatever you wanna call it, the AVR if the head was run below 1800 RPM "without" a load? The reason I ask this is I would like to be able to let my engine warm up at an idle before it runs at "generating" rpm.  Once the engine is warmed up, I would open the throttle and then apply the load to the generator. What do you think?

Thanks!
Ben

I can not think of any way there would be a problem with what you propose to do.

[tinkerer]

Okay, thanks for your input!
Ben

[vdubnut62]

I have the same setup from Tom @ CCG. I warm mine up at slow speed before I run at full speed and load and I never had a problem.
Ron

[tinkerer]

Good to hear!!

Ben

[Ronmar]

Yep, as long as you are not trying to put a load on it you should be fine.  The brushed regulated ST appears to still use the harmonic winding as a power source for the regulator. This makes them RPM dependent, IE: at idle there is just not much energy available to feed the field. I do not think those regulators have any active RPM/Frequency sensing built in because of this.   At any rate, if no load is applied to the generator it takes very little current to excite up to output voltage.  But under RPM is why you should have the field current circuit properly fused.  If the engine quits or droops in RPM, the AVR will do it's best to maintain rated output voltage as the generator spools down.  If not limited, it will apply enough current to the field to possibly do damage to something, usually the AVR.   

The Brushless regulators Tom is using are a little more sophisticated and I believe have frequency sensing and don't excite outside of the 57-63HZ range.  And the field output is fused just in case...