I've seen several Nuclear Reactor video tutorials, and they all seem to use a HV Transformer to allow their reactor to safely output its power to an MFSU. However my reactor has no transformer and safely outputs to a MFSU. What exactly determines the reactor's EU packet output so that I know when I must use a transformer?

  • How many EU/t is it generating? Oct 22, 2013 at 20:07
  • If that is a factor then it should be part of the answer, it shouldn't matter, I'm asking how it works.
    – Ender
    Oct 22, 2013 at 20:56
  • Yes, of course. But I'm gathering data to make sure something else isn't going on. If it's outputting 2000 EU/t and you're not using an HV transformer, that's important to know before answering. Oct 22, 2013 at 21:03
  • Ahh, I understand, no I tested it using only 4 single Uranium Cells
    – Ender
    Oct 22, 2013 at 21:05

1 Answer 1


The size of output packets is determined entirely by how much EU/t the reactor is putting out, which in turn determines whether and which transformers are needed.

An HV transformer is typically used because MV equipment maxes out at 128 EU/packet (regardless of EU/t), and a reactor design can easily scale up beyond that. The HV transformer is unusual in that it can accept any size of packet, which allows it to handle the typical High Voltage or Extreme Voltage that a reactor can put out.

Technically, a piece of equipment or wire can exceed its rated voltage if there are multiple sources of packets – two 32 EU/t sources will put 64 EU/t into the wire, but since the packets are only 32 EU each it still counts as LV. This makes using an EU meter to figure out wiring tolerance not actually very accurate, and you simply have to know what everything is outputting instead. So, a reactor being a single source, you can know its EU/packet will always match its EU/t, and you can figure out how big the packets it outputs are by measuring its EU/t.

For reference:

  • LV is up 32 EU/packet
  • MV is up 128 EU/packet
  • HV is up to 512 EU/packet
  • EV is up to 2048 EU/packet, but is confusingly also used to refer to greater voltages too
  • so how much eu\t can i get befor its considered 32EU\packet?
    – Ender
    Oct 23, 2013 at 19:20
  • @Ender Does the edit clear that up? Oct 23, 2013 at 23:57
  • that more than clears it up, you've also instructed me some on how Eu works period, thanks alot!
    – Ender
    Oct 24, 2013 at 0:17

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