Motor starting surge on a generator?

[qcroanoke]

I've heard you guys say many times "add some incandescent bulbs to the led load"
Could that help?

 

[synchro]

What would really help is a video with sound showing the genset and the lights together. Maybe tach or line voltage also. Then we can see the sequence of things.

I agree.
I also think including an incandescent lamp connected to an LED lighting circuit could provide additional insight into what's going on.
It's conceivable that a higher frequency transient, for example when a starting capacitor is disconnected, could interfere with electronics in LED lights but would have minimal impact on an incandescent bulb.

 

[synchro]

I've heard you guys say many times "add some incandescent bulbs to the led load"
Could that help?

It looks like we brought up incandescent bulbs within a minute of each other.

I was thinking of an incandescent bulb more as a diagnostic tool rather than a fix for flickering LED problems. If there are dimmers driving the LED lamps, then I think an incandescent load placed on the dimmer output could possibly help. I think it's less likely that putting an incandescent load directly on the AC supply powering the LED lights would help, but it doesn't hurt to try.

 

[JoeStillman]

If there is a long cable with the generator at one end and the ice cream machine and the LED's at the other, the fix may not be at the generator. Maybe you need to separate the feeds.

If you stand by the generator while someone pours a cone, do you hear the generator grunt?

 

[ptonsparky]

If there is a long cable with the generator at one end and the ice cream machine and the LED's at the other, the fix may not be at the generator. Maybe you need to separate the feeds.

If you stand by the generator while someone pours a cone, do you hear the generator grunt?

Blowing black smoke might be an indicator. Of something.

 

[Deltaforce]

LED flicker, augur motors not operate, also to check

 

[synchro]

If the ice cream machine motors are single phase, perhaps the starting capacitors are degraded and causing an eccessive starting current. If a meter has not been used to measure the peak current in "inrush" mode, doing so could be helpful to determine whether the starring current is reasonable or excessive.

 

[ptonsparky]

Could the mix be too cold?

 

[TwoBlocked]

I'm a gonna wait 'til we hear back from Zbang, the OP

 

[Joethemechanic]

Could the mix be too cold?

I like it that way

 

[synchro]

Alternatively, you could use a small inverter generator on the lighting like they do to power up those tripod puffer lights for road construction. You said 100s of LEDs. If they're like 10W ea, that's just a few kWs.

Another alternative if the load from the LED lights is a few kWs would be a double conversion UPS. This might even provide some safety advantages by keeping the lights on if the generator power drops out.

 

[ptonsparky]

Check my crude math but two 2 Hp starting at the same time and, assuming 6 times FLA, is going to equal about 24% of that 75kva. I guess there could very well be a dip in voltage.

746*2*2*6=17904

 

[TwoBlocked]

Check my crude math but two 2 Hp starting at the same time and, assuming 6 times FLA, is going to equal about 24% of that 75kva. I guess there could very well be a dip in voltage.

746*2*2*6=17904

What you say is true, but is not the whole story. If the generator is loaded at, say, 12.5% when the additional load is put on, it sees a momentary 200% increase followed by a quick reduction down to only a 30% increase. However if the generator is loaded at, say, 75% when the additional load is put on, it sees a momentary increase of only 33%. Much easier for the governor and engine to handle.

I can't be the only one that has heard a generator go WAAAHHH Waahh wah on a sudden load increase. Can I hear an AMEN? (c'mon, Joe)

Oooops, I wasn't a gonna post ...

 

[synchro]

The initial relatively quick dip in the generator voltage when a motor is started will be due to the reactance of the generator's windings. This will be followed by a drop in voltage as the engine speed slows and then recovers, but that is a slower process. See the Cummins document at the link below which has info on this.
The transient impedance of generators is usually substantially higher than the impedance of transformers. This makes them susceptible to voltage drops from motor starting currents.

https://mart.cummins.com/imagelibrary/data/assetfiles/0057945.pdf

The electronics in LED lights can respond to quick voltage changes more readily than incandescent lamps, and sometimes in an objectionable manner.

And so I think it may be easier and more effective to focus on getting cleaner power to just the LED lights, rather than making changes to the existing generator setup.

 

[Deltaforce]

And so I think it may be easier and more effective to focus on getting cleaner power to just the LED lights, rather than making changes to the existing generator setup.

That bring power quality issues in discuss.
And 80% or more power quality issues, wiring and grounding issues.
So what such issues may here?

 

[Flicker Index]

And so I think it may be easier and more effective to focus on getting cleaner power to just the LED lights, rather than making changes to the existing generator setup.

Having to feed lighting circuit and all else circuit to every vendor would be a significantly more logistical challenge than simply getting a small pony generator to serve the problematic load. The little generator would be a +1 item that's deployed as needed to solve a problem.

 

[Joethemechanic]

I can't be the only one that has heard a generator go WAAAHHH Waahh wah on a sudden load increase. Can I hear an AMEN? (c'mon, Joe)

Yeah I like that bark, older machines were better though, new ones are too quiet

My Favorite bark is from a Lincoln SA200 pipeliner welder with a straight piped Continental F-162 flathead 4. (that's the way Lincoln built them back in the day) Mostly the "Red Face" and earlier versions like the "Short Hood". Whenever I hear that bark I feel like something is getting done



A short hood is the red 57 Chevy convertible with Rochester Mechanical fuel injection or maybe the Knucklehead Harley of the welding world

 

[kwired]

Wouldn't supplying an induction motor driving a rather low torque (once up to speed) yet high inertia type load help stabilize voltage when these other motor starts occur? Even if all it does is drive some flywheel that doesn't serve much other purpose?

 

[Joethemechanic]

Wouldn't supplying an induction motor driving a rather low torque (once up to speed) yet high inertia type load help stabilize voltage when these other motor starts occur? Even if all it does is drive some flywheel that doesn't serve much other purpose?

I'd think so. When it's in induction generator mode it uses reactive current from the line, but produces active current. Maybe add some capacitors to supply the reactive. They can be driven with an engine too for a "booster"/three phase converter

 

[JoeStillman]

I can't be the only one that has heard a generator go WAAAHHH Waahh wah on a sudden load increase. Can I hear an AMEN? (c'mon, Joe)

My first experience of this was with a Caterpillar 3516 1500 kW diesel when we added the last 5 kW on the 1500 kW load bank. The voltage was running a little high because of the last time it synched with utility. So the load bank wasn't 1500 kW anymore. it was 1500 x V₂²/V₁²