# A Player's Guide to Redpower 2 Blutricity

Discussion in 'Mod Discussion' started by Omicron, Jan 4, 2013.

1. ### OmicronOver-AchieverTrusted User

Introduction

There used to be an introduction here, but then, once upon an edit, the forum helpfully reminded me that I can only have 10,000 characters in a single post. For your benefit, the introduction has been sacked.

Blutricity 101

1.) Blutricity is modeled after real electricity, though it is not a 100% exact representation. Still, it is a lot more complex than the energy networks of many other mods, especially those of Buildcraft and Industrialcraft, with which most players are familiar.

2.) Blutricity is a low power system. Its machines and components make do with very small amounts of power compared to many other mods.

3.) All blutricity blocks are conductors. That means you don't need to hook everything up with wiring. So long as a blutricity block is touching another one that is already powered, it will also be powered. For example, you can have an entire line of bluletric furnaces and connect a cable to only one of them, but all of them will still receive power. This allows for some extremely compact builds with barely any wiring.

4.) Keep in mind the distinction between "energy" and "power"; contrary to popular belief, the terms are not the same, and in fact have very specific definitions. If you think of Buildcraft, energy is MJ; in other words, the absolute quantity. Whereas power is MJ/t; namely, the rate of energy over time.

5.) Your unit of blulectric energy is the Joule. Your unit of power is the Watt, which is equal to Joules per second (not per tick). Power is calculated by multiplying voltage with current (amperage).

6.) As a result, there is no such thing as "Watt per tick". Watt is a unit of power, not energy, and already includes time by definition. 1 W = 1 J/s = 0.05 J/t.

7.) One kilowatt (1 kW, or 1,000 W) converts into 1 MJ/t (20 MJ/s) worth of Buildcraft power, using the blulectric engine. Therefore, 50 J equal 1 MJ. You cannot convert MJ into Blutricity.

8.) Voltage equals the charge status of the energy network. If a machine shows its energy meter filled to 50%, it will be at 50V. If it is full, it will be at 100V. Same goes for cables and other blulectric things, which store small amounts of energy themselves due to a phenomenon called self-capacitance (see 22. below).

9.) When adding or removing components to/from a blulectric energy network, voltage will fluctuate and swing back and forth significantly in the beginning. Pay it no mind; after a minute or so it will have stabilized.

10.) High voltage cabling needs a long time and a lot of energy to get going due to the aforementioned self-capacitance. You will have to wait a good while before significant energy flow will occur, but after that initial chargeup, it will work normally.

11.) Blulectric devices will never explode due to voltage. High voltage cabling will simply not connect to low voltage devices.

12.) Machines will begin operating at roughly 60 V. A battery box begins discharging itself at roughly 80 V, and it will begin charging itself at roughly 90 V. Machine working speed and battery box charging/discharging rate increase or decrease with voltage, as applicable. A battery box most often stabilizes around 91 V or 79 V when charging/discharging under common loads.

13.) The higher voltage an energy generating device possesses, the faster it generates energy. Using buffer storage between generators and consumers to keep the voltage at least partway up is a good idea.

14.) Every blutricity block has a certain electrical resistance (see 23. below). Resistance causes current to have greater difficulties moving through a conductor the longer it is, the higher the individual resistance of each piece is, and the more amperes there are. In order to overcome the resistance, voltage is lost while amperage remains constant. The amount of voltage required is called the electric potential difference, or voltage differential, as in 'the difference in voltage between the beginning and the end', and the more resistance there is, the higher the differential will need to be to move the full current over the full distance. If there is less voltage available to spend than would be required, then not all the current can be moved at once, and thus the energy transfer is getting slowed down. This has the following implications:

15.) Power loss over distance: since power is volts * amperes, and voltage decreases over distance as you are expending it to move the current, power decreases over distance as well. That means that at the end of a long cable, you're getting out less than you put in on the other side. This energy loss scales with distance, and the amount of current: very low power transfers of only a couple dozen watts (less than 1 A) are close to lossless, but a wind turbine spinning in a thunderstorm may force more than 40 A into the energy network, and that cable is going to be crying for mommy. Only a huge voltage differential can move that kind of current over more than just a couple of blocks, and therefore there's going to be a lot of loss (if the current can even be moved at all).

16.) Electric choke: In some cases, you are limited in how much voltage you can expend to move current. For example, a battery box typically sits at 91 V while being charged, and a wind turbine will stop producing power at 100 V because this equals maximum charge. Thus, the maximum voltage differential possible between these two components is somewhere around 8 V (91 V at battery box -> 99 V at wind turbine). But, what happens if the wind turbine is outputting so much current and/or the cable is so long that a differential of 8 V is not enough to move it? What is you need 10 V, 11 V, 15 V? In this case, you have built a choke. It is called that because you are 'choking' your wind turbine with resistance. If only 8 volts is available for spending, then that much will be spent and a matching amount of current will be moved. Any extra current generated by the wind turbine that cannot be moved is simply wasted, and will never reach the battery box. The effect is even visible to the player directly: since a wind turbine will engage the brakes when there is nowhere for the power to go in order to preserve durability, a choked turbine will stutter back and forth every couple seconds between spinning fast and slow, fast and slow.

17.) Practical example: Using blue alloy wire with its resistivity of 0.02 Ω, how long can your wire be without the resistance getting so high that a voltage differential of 8 V won't be enough to transfer all the current? Ohm's law says that resistance = voltage diff. / current. Now all we need to do is insert our 8 V, as well as the current we want to transfer, and divide the resulting resistance by 0.02 Ω to get the number of blue alloy wires. For a Thermopile (0.5 A), this results in 800 blocks; for three solar panels (6 A), 66 blocks; for a wind turbine going at full tilt (50 A), 8 blocks. That's right, after roughly 8 blocks, common blue alloy wire starts to have difficulties with wind turbines, and at a mere 16 blocks it will throttle the turbine down to half its maximum output, wasting the rest. You may want to find a better solution here. Note: in actual gameplay, you should always have a safety margin because voltages fluctuate and you don't want your generators to randomly stutter. From my testing, I'd say it's best if you take 10% off of the results you get with this formula.

18.) Countermeasures: The simplest way to lower resistance and avoid chokes is to make the wires shorter. If that is not possible, you can put a second cable next to the first if there's room. Fully separate or directly adjacent both work just fine, Redpower has no issues with loops and meshes. After all, if one cable can manage 20 A over the 10 V you have available, then two cables can manage 20 + 20 = 40 A over the same 10 V. Another option would be using something that has less resistance per block, but with the current options available only the voltage transformer qualifies, and that gets expensive really quickly (and looks extremely silly to boot). The final option is to use higher voltage cabling. Because these carry the same wattage at higher voltage, the result is a vastly reduced amperage. And with less current to move, resistance is much less of a problem.

Numbers Reference

19.) Power output of generators: Thermopile, up to 50 W depending on setup; solar panel, up to 200 W during the day, 100 W average over day and night; horizontal windmill, up to 2500 W depending on wind and height; vertical wind turbine, up to 5000 W depending on wind and height. In Mystcraft storm ages, windmills and turbines have been observed to double their output. Voltage below 100V will reduce these numbers.

20.) Power draw of consumers: Furnace and alloy furnace, 1000 W and about 5000 J per operation; sorters/retrievers/managers, very small amounts depending on number of items handled, typically under 5 W; blulectric engine, 1000 W per MJ/t generated, up to ca. 25 kW; pump, around 815 W, moving one block of liquid for 1750 J. Frame motors have an energy requirement of 10 J per block moved per action, panels/covers count towards the frame they're installed in and don't cost extra.

21.) Power storage of buffers and batteries: Battery box, 300 kJ; BT battery, 75 kJ; charging bench, 150 kJ; sonic screwdriver, 20 kJ (good for 400 uses); internal buffer of machines, 25 kJ.

22.) Self-capacitance of conductors: Blue alloy wire, ca. 1 kJ; voltage transformer, ca. 25 kJ; 10 kV wire, ca. 78 kJ. These are somewhat imprecise measurements.

23.) Specific resistivity of conductors: Blue alloy wire, 0.02 Ω; voltage transformer, 0.01 Ω; 10 kV wire, 2 Ω; other blulectric devices, 0.02 Ω.

Blorph, MagusUnion, grimmel and 15 others like this.
2. ### OmicronOver-AchieverTrusted User

RESERVED for expansion (if Redpower ever updates again)

3. ### dakamojoActive Member

Does anyone have any numbers for how height affects vertical wind turbines? And how blocks around them affect them? I want to place two or more vertical wind turbines but I want to ensure that they are not decreasing the efficiency of each other.

4. ### DemocretesOver-AchieverMod Developer

Something you might want to add is how much energy wires need to be fully saturated. Other than that excellent guide

5. ### OmicronOver-AchieverTrusted User

I tested windmills in a superflat world, preset "redstone ready". That puts you at y=64, and I erected a windmill about 10 blocks up from that. Despite being well below 50% map height, I still saw it hit near-maximum output twice during my tests. In fact it was all over the place, seemingly random. So I don't believe height is that big of an issue - although I didn't do any comparison tests.

Placing blocks near them doesn't have a big effect for single blocks, but walling off the entire back of a vertical windmill absolutely crippled it. Mind you, that was quite a lot... close to 100 blocks, right next to it.

6. ### 5arganMember

afaik only the wind speed (changes every day) and it being blocked or not affect the output, but I'm afraid I don't have any precise numbers on this

8. ### OmicronOver-AchieverTrusted User

I've literally been testing this for hours now, and it's proving to be extremely difficult. The numbers I'm getting are all over the place and can vary by as much as 40%, especially on the 10 kV wires. It would be great if someone else could contribute their results to this as well.

So far it seems like it can be narrowed down to this:

Blue Alloy Wire: 1 kJ
Voltage Transformer: 30 kJ
10 kV Wire: 60 kJ

But, again, these numbers are extremely unreliable.

Haha, wow. Mystcraft must really be messing with the wind speeds in those ages

9. ### DemocretesOver-AchieverMod Developer

I'd like to help, but I have no idea how you're getting numbers in general. The numbers you have sound like they fit in with the rest of the system.

The only solution to get 100% accurate numbers would be to ask Eloraam, but that would be

So we'll go with your numbers.

10. ### OmicronOver-AchieverTrusted User

Well basically I'm leveraging NEI to help me out here. I know that BT batteries store 75 kJ of energy, and NEI tells me that the charge status of BT batteries is counted via their damage value in 1500 steps (empty is 0/no damage value, completely full is 1, and then it declines up to 1499 which is minimum charge). Now, I also know from the blulectric engine experiments that 50 J equals 1 MJ worth of Buildcraft energy, and 75,000 divided by 1,500 is 50. So by sheer coicidence, I can count every step of the BT battery's charge meter as 1 MJ. Not terribly accurate, but by repeating the experiment several times, a clear trend should manifest, and the rest is just rounding results to numbers that humans would actually pick (no human assigns arbitrary values, we always try for "nice round numbers").

I then plop down an empty battery box and fill it to the brim via batteries. This ensures that internal storage is capped at a fixed value (of 300 kJ, but the value is irrelevant so long as it is fixed, because that ensures that the experiment is repeatable), and the charge meter is sitting at roughly 80 V. This is because the battery box discharges its internal storage until its charge meter (and by extension, the surrounding energy network) reaches about 80 V. This represents the base state from which all experiments run.

I then connect my test subject to the battery box. For example, let's say I am placing a single piece of blue alloy wire right next to it. Since that wire starts out at 0 V, i.e. containing no energy at all, the system attempts to even itself out by transferring some energy from the battery box over into the wire, until both the wire and the battery box are at the same charge level. However, due to the way I set up the battery box, any energy draining out of the battery box immediately triggers its internal storage to discharge in an attempt to replace the missing energy and return to the 80 V mark. In the end, both the wire and the battery box will sit at 80 V, and the amount of energy that went into bringing the wire to that level is now missing from the battery box's internal storage.

I now take a full BT battery and charge up the battery box's internal storage up to full. And because I know exactly how much energy every step of the BT battery's damage value represents, I can use it to measure the amount of energy that the blue alloy wire "stole" from the battery box. Now, there is some imprecision in this measurement, because unfortunately, blulectric charge tends to overswing while it balances itself out, and thus it's not possible to hit 80 V exactly. One measurement you may be at 79 V, the next at 84 V, and the one after that at 81.5 V, and so on. That's yet another reason to run the experiment multiple times to collect average figures.

In this case, the blue alloy wire generally behaved very agreeably (in contrast to the other two test subjects) and repeatedly posted the same 16 steps of difference in the BT battery's damage value for each piece of wire connected. In other words, 16 MJ worth of energy, or if multiplied by 50 again, 800 J. Since we're hovering around 80% charge level and not 100%, I then divide the result by 4 and multiply by 5. The end result is 1000 J, or 1 kJ, which coincidentally also happens to be a very "human" number. Therefore I conclude that the empirically measured value for the blue alloy wire is pretty much spot on.

Unfortunately the other two experiments weren't nearly as reliably reproducable as this one. Which is odd, considering the opposite should be true - large numbers should render measuring imprecisions irrelevant. But apparently, there are some strange goings-on here, especially with 10 kV wire.

11. ### DemocretesOver-AchieverMod Developer

Using your procedure I come up with very similar results for the blue alloy wire, but the results for the transformer and 10kv wire are higher. For the transformer, I'm getting close 40kj versus your 30, and for the 10kv wire, I 'm bringing in 70-80kj. These results are fairly consistent with me. It is highly possible that I'm making a mistake somewhere along the lines so don't trust my results entirely. I am getting odd results sometimes, a number thats 5-10kj off of the rest of the group, but they're still fairly consistent. I've tested each of the items 10 or so times for accuracy.

12. ### OmicronOver-AchieverTrusted User

Yes, that's exactly my problem. It just doesn't want to fit together. I, too, got up to 80 kJ for the 10 kV wire, when I was testing single wires. But due to the high margin of error, I wanted to test a larger amount, so I started hooking up lines of 10 to 20 wires at a time instead. And those posted completely different results than the single wire. They did, however, do one thing I wanted - the variance of results shrinked by an order of magnitude. And since both the 10 and the 20 wires in a line posted similar results while the single wires were somewhere else entirely, I'm currently tending towards believing the 60 kJ more than the 80 kJ. Heck, maybe I should go and hook up 100 wires in a line and see what happens.

I honestly expected the 10 kV wire to be around 100 kJ, namely 100 times the regular blue alloy wire, since it bears 100 times the voltage and self-capacitance is defined as the amount of energy required to raise voltage by 1 V in a given material. But empiric testing definitely points to a lower value, no matter which way you look at it. So the self-capacitance of 10 kV wire is lower than that of regular blue alloy wire (but the total energy stored is still higher, due to the higher voltage).

13. ### esotericistMember

1 W = 1 J/s = 1/20 J/t

since a tick is 1/20 a second?

14. ### OmicronOver-AchieverTrusted User

Hah. Yes, yes it should! That's why more eyes are always good

I have to rework a few bullet points anyway, because unfortunately Eloraam didn't leave it at a simple block-based voltage loss over distance... extra testing with some high output windmills made clear that she's actually modeling electrical resistance as well. No joule heating, thankfully, that would make things really convoluted. But still resistance according to Ohm's Law. Currently trying to measure some sample resistances.

P.S.: Tested self-capacitance yet again, this time with a 100 block long line of 10 kV wire. Still getting around 60 kJ/wire.

15. ### OmicronOver-AchieverTrusted User

Some numbers on electric resistance:

3 solar panels -> 60 blue alloy wire -> blulectric furnace smelting cobblestone:
67.10 V on the first wire to 60.10 V on the last wire at 6 A, meaning (R = (67.10 - 60.10) / 6) / 60 = 0.019444 Ω

3 solar panels -> 60 blue alloy wire -> battery box charging its internal storage:
98.11 V on the first wire to 91.12 V on the last wire at 6 A, leading to pretty much the same result, confirming that blue alloy wire follows Ohm's Law

4 battery boxes -> voltage transfoermer -> 100 10kV wire -> 3 voltage transformers with 3 blulectric furnaces smelting cobblestone:
7747.62 V on the first wire to 7670.57 V on the last wire at 0.3932 A, meaning (R = (7747.62 - 7670.57) / 0.3932) / 100 = 1.959563 Ω

Rounding up to "nice human numbers", you can say that the resistance of blue alloy wire is 0.02 Ω per block, and the resistance of 10 kV wire is 2 Ω per block.

EDIT:

1 battery box -> 1 blue alloy wire -> 20 voltage transformers -> 1 blue alloy wire -> 1 blulectric furnace smelting cobblestone:
77.64 V on the first transformer input to 75.23 V on the last transformer output at 13.40 A, meaning (R = (77.64 - 75.23) / 13.4) / 20 = 0.008993 Ω

That is one heck of a tiny resistance. Fun fact - if you make a "wire" out of transformers, it can go much much longer than normal blue alloy wire

16. ### OmicronOver-AchieverTrusted User

( Updated with some reordering and detailing of electrical resistance. )

17. ### Evil HamsterActive Member

Time to re-wire my house!

18. ### Evil HamsterActive Member

What is the resistance of a battery?

19. ### OmicronOver-AchieverTrusted User

I haven't tested that. I suppose since blulectric devices conduct between each other you could technically make a long string of for example battery boxes and eschew wires, but it's never come up in any of my builds. I'll make a note for future testing.