Help calculating power requirement

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Trebor
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Help calculating power requirement

Post by Trebor » Sun Dec 09, 2018 4:35 pm

I have several problems with calculating power requirements and would like someone to show me where I'm going wrong.

I have an electric furnace (drain 6kw, consumption 180kw) with a level 3 productivity module (-50%) and a level 3 efficiency module (+80%). My math: 6000 + 180000 *(1 + .8 - .5) = 240000, but the games says consumption is 233kw(+30%) drain 6kw = 239000. A difference of 1kw.

The wiki says arithmetic/decider combinators use 2kw, game says 1kw.
For inserters wiki: drain 400w, consumption 13kw, game: drain 400, consumption 13.2kw (13.6kw total).
Fast inserters wiki: drain 500w, consumption 46kw, game: drain 500w, consumption 46.2kw (46.7kw total).
Lamps wiki: 5kw, game: 5kw.

So according to my calculations (using the larger value from wiki or game) my steel smelting unit uses:

120 furnaces: 28.8mw
240 inserters: 3,264kw
4 fast inserters: 186.8kw
31 lamps: 155kw
16 combinators: 32kw
Total power:32,437,800

Now the wiki says accumulators will transfer 300kw per second, the game list this as 300kw consumption. That means my power usage should be satisfied by 108.18 accumulators: 32,437,800 / 300000 = 108.18.

For OCD reasons I'm using 112 (33.6mw) between the main power grid and the smelting unit, yet when the furnaces are turned the accumulators drain faster than they are charged by the 262 steam engines (235.8mw).

What am I missing in my calculations?

Edit: corrected steam mw.
Last edited by Trebor on Mon Dec 10, 2018 1:02 am, edited 1 time in total.

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disentius
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Re: Help calculating power requirement

Post by disentius » Sun Dec 09, 2018 9:40 pm

Not sure, i get roughly the same calculated usage
Suspect it has to do with the way you connect the accumulators; see https://wiki.factorio.com/Electric_system
How does your power graph look?
Accumulators drain last. i put double poles in, one set for input, one for output.
After some fiddling:
Acumulator test1.png
Acumulator test1.png (659.18 KiB) Viewed 461 times
Put two sets power poles in which both cover all accumulators (input from the left, output to the right.)
Remove connections between the two sets.
Powerpole placement.png
Powerpole placement.png (837.17 KiB) Viewed 461 times
testsetup:
testsetup.png
testsetup.png (3.51 MiB) Viewed 460 times
Last edited by disentius on Sun Dec 09, 2018 9:56 pm, edited 1 time in total.

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disentius
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Re: Help calculating power requirement

Post by disentius » Sun Dec 09, 2018 9:54 pm

Out of curiosity: What are the advantages of this setup?
Accumulators are the last to decharge and the last to charge. if they start draining, you would need to up your power production or shut down parts of your factory in all cases.

Trebor
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Re: Help calculating power requirement

Post by Trebor » Mon Dec 10, 2018 1:01 am

Here is a picture of how the smelter is powered:
Screen Shot 2018-12-09 at 7.35.20 PM.png
Screen Shot 2018-12-09 at 7.35.20 PM.png (53.82 KiB) Viewed 443 times
The main power grid is at the bottom, all power for the smelter is through the accumulators, they charge and drain at the same time.

The advantage is the maximum power usage for each production unit is set based on number of accumulators x 300k. The production unit cannot draw more so cannot effect any other unit's power.

Looking at the power window it shows the accumulators as supplying 28.4mw not the 33.6mw I calculated:
Screen Shot 2018-12-09 at 7.48.08 PM.png
Screen Shot 2018-12-09 at 7.48.08 PM.png (1.15 MiB) Viewed 443 times

Could my math be off for how much power the steam engines produce: 262 x 900kw = 235.8mw
Screen Shot 2018-12-09 at 7.55.35 PM.png
Screen Shot 2018-12-09 at 7.55.35 PM.png (885.88 KiB) Viewed 443 times

Trebor
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Re: Help calculating power requirement

Post by Trebor » Mon Dec 10, 2018 1:30 am

Maybe there is nothing wrong with my calculations. I may be thinking just because no research is being done I have enough steam engines. But there are 53 production units being asked to produce, 38 of them turned on and doing work, 1 is out of resources, and 14 are out of electricity.
Screen Shot 2018-12-09 at 8.22.42 PM.png
Screen Shot 2018-12-09 at 8.22.42 PM.png (509.1 KiB) Viewed 439 times

I really wish the "Electric network info" window didn't count accumulators that were being charged as sources of electricity. See last pic of prior post.

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Re: Help calculating power requirement

Post by JimBarracus » Mon Dec 10, 2018 6:21 am

Trebor wrote:
Mon Dec 10, 2018 1:01 am
The advantage is the maximum power usage for each production unit is set based on number of accumulators x 300k. The production unit cannot draw more so cannot effect any other unit's power.
But it also cant draw more power because you calculate the maximum power for this setup.
As long as you don't expand it power should always be fine.
While writing this I understood what this setup is meant to do.
It's a wacky workaround for the power switch with a massive downside.

Since the consumption and the throughput are so close by each other it should take an ethernity to recharge the batteries without switching the smelting facility off.

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disentius
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Re: Help calculating power requirement

Post by disentius » Mon Dec 10, 2018 11:29 am

You misinterpret the GUI readings. (we all do that, it's a klutz)

Satisfaction -> Is all required power delivered? Full green bar means yes
Looks like your furnaces are not all active at the moment, so they require less power than the maximum you calculated.

Production-> How much of the total power production (in this case: accumulator production) is used?
If this one is full, you power production for that segment is maxed out. Test it by removing a couple of accumulators: satisfaction will turn yellow.


Accumulator charge-> if this one is not full, it is either charging, or your main grid doesn't produce enough power to satisfy the drain at the other end AND charge the accumulators at the same time.

My test setup:
Main grid power
- all power needed is delivered (Satisfaction)
- 40%-50% of total power capacity used (production)
- Accumulators take 30MW and get all power they need
main grid power.png
main grid power.png (200.03 KiB) Viewed 413 times
Accumulator grid power
- all power needed is delivered (Satisfaction)
-Production capacity is almost fully used (Production, this is what you want to limit as I understand)
Accumulators get all power they need to produce and recharge (Accumulator charge) If this one goes down over time, they are not getting enough power from the main grid.
accumulator grid power.png
accumulator grid power.png (211.42 KiB) Viewed 413 times
Looking at your power GUI's:
- Smelter setup gets all the power they want from the accumulators(Satisfaction)
- accumulators are not fully charged, so they probably dont get enough power from the main grid. (all other entities not behind a secondary accumulator grid, like miners in your screenshot, get power first.)

There is something strange going on with your power output from the accumulators. My test setup produces 30.6MW max from 102 (30.6 MW) accumulators, a load of 99%. Your setup maxes out at 28.4 MW for 112 accumulators. Could not reproduce that.
112 accumulator test setup uses 88% of max production-> 29,7/(112*300MW)
accumulator grid power 112.png
accumulator grid power 112.png (221.46 KiB) Viewed 413 times

Trebor
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Re: Help calculating power requirement

Post by Trebor » Mon Dec 10, 2018 5:40 pm

Yea, I knew it was a user problem it just wasn't the one I thought. The local grid information does sow that my calculations were right. The problem like you said was not enough power in the main grid. I had another unit where after adding modules the power usage exceeded the number of accumulators, in that case the satisfaction bar became red.

By the way, even with an underpowered main power grid as long as I have the correct number of accumulators for each unit they run at 100% or not at all.

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Re: Help calculating power requirement

Post by bobucles » Tue Dec 11, 2018 8:49 pm

I wonder if something screwy is happening between your accumulator bridges. Ideally all power should be going from central => outpost so all the numbers should be okay. However there is no explicit reason that energy can't travel from outpostA => central => outpostB, even though the outposts have no generation capacity of their own. If the energy is taking unusual paths through the system then it might cap out the accumulators without necessarily satisfying the local demand. The electrical grid wasn't exactly made for such shenanigans.
Could my math be off for how much power the steam engines produce: 262 x 900kw = 235.8mw
Your engines should peak at 235mw as calculated. If the steam engines are starving they will cap out at a reduced output. The UI is very bad at showing a steam deficiency so make sure your 1:20:40 setups don't have anything broken.

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Re: Help calculating power requirement

Post by Trebor » Wed Dec 12, 2018 4:43 am

bobucles wrote:
Tue Dec 11, 2018 8:49 pm
However there is no explicit reason that energy can't travel from outpostA => central => outpostB, even though the outposts have no generation capacity of their own.
Actually it's: outpostA <= accumulatorsA <=> central power <=> accumulatorsB => outpostB, accumulatorsA can't charge accumulatorsB.

bobucles wrote:
Tue Dec 11, 2018 8:49 pm
Your engines should peak at 235mw as calculated. If the steam engines are starving they will cap out at a reduced output. The UI is very bad at showing a steam deficiency so make sure your 1:20:40 setups don't have anything broken.
I think the engines not hitting max may have something to do with the coal I saw mixed with the solid fuel, but it's more likely because of water supply problems (fluid physics).

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