Energy tesseracts are sensitive to power being drawn on the other end; the entire Buildcraft energy network is sensitive.
Power mechanics differ between conduits and conductive pipes (although the latest revisions by CovertJaguar made them more similar than they were before).
Conductive pipes split power by the normal BC pipe splitting mechanic: an even split at every junction. So imagine you have a long line of conductivbe pipes between your tesseract and the engines. Now attach three consumers to the side of that long pipe. The first consumer gets 50%, and 50% passes on. The second consumer gets 50% of what's left (25% in total) and the rest (another 25%) passes on. The third consumer gets 50% of what's left (12.5% in total) and the remaining power (another 12.5%) reaches the tesseract.
However, this applies only in the case where each consumer can actually consume all the power they are eligible to receive. If you're pushing 100 MJ/t through the pipe, and the first consumer is a quarry, it will take the 50 MJ/t it's eligible for because a quarry can actually use 50 MJ/t (roughly). But if it's a powered furnace, and its internal buffer is full already, it will only take 2 MJ/t out of the 50 it could draw. So instead of 50 being diverted and 50 passing on, 2 will be diverted and 98 will pass on. There is no loss involved with machines rejecting power.
Redstone energy conduits, on the other hand, are much more comparable to a peer-to-peer network. Each conduit section that has an engine attached to it sees all consumers, and will split the power it receives from its engine(s) evenly between all of them. Meaning, with conduits, each of the three consumers and the tesseract in the example setup above would receive 25%, if they were able to consume that much.
In regards to burst output of Buildcraft compatible engines: both wooden conductive pipes and redstone energy conduits accept the entire burst from the engine and buffer it. Assuming that a Railcraft industrial steam engine strokes once per second (completely made up figure, don't quote it), it would burst out 8 * 20 = 160 MJ per stroke. The conduit or wooden pipe will buffer this and then transmit it at the rate the network can accept it. If only a single powered furnace is connected, it will send at 2 MJ/t; if there's a tesseract with full power draw and a powered furnace connected, it will send at 127 MJ/t (2 for the furnace, 125 for the tessearct which sends 100 and loses 25).
Both conduits and wooden pipes can fill up their internal buffers, and what happens then depends a lot on which version of Buildcraft and its various associated mods you use. In the current 1.5.2 ecosystem, engines will not be able to output anymore and will continue to fill their internal buffer, eventually topping it up. And what happens then depends on the engine in question - some go boom, some blow a valve and vent all their energy, some simply stall and require the player to fix it.
If you attach a Buildcraft compatible engine directly to a machine, then how much energy is transferred depends on the machine's burst input limit and the engine's stroke length. A Buildcraft pump for example has a burst input limit of 10 MJ per tick. If you attach an engine that outputs more than 10 MJ per stroke, that engine will start filling up on internal energy because it can't output anymore, even if the engine's power output is not too high for the pump. For example, while the pump can use 10 MJ/t (which happens to be identical to its burst input limit, but doesn't have to be), a stirling engine producing just 1 MJ/t strokes so slowly that it cannot possibly transfer all of its power because of its 52 tick stroke length.
However, when the stirling engine heats up, upon reaching the red stage its stroke length will drop down to 8 ticks, during which the stirling engine only generates 8 MJ but can transfer 10. Therefore, a single stirling engine powering a single pump by being directly attached will heat itself up to red and then flash back and forth between yellow and red, much like a redstone engine would (which it does because of similar reasons, except that in this case the redstone engine's own burst
output limit is so low that the engine must heat up in order to stroke fast enough).
Any other questions I can help you with?
