These were based on the fact that accuracy decreased significantly as the length of the pyrotechnic delay
elements increased and that the downlines may be severed (cutoffs) during a blast before the firing signal reaches the detonators, leading to dangerous misfires.
The electronic detonator, instead of having a pyrotechnic delay (effectively a chemical burning reaction which has a certain time to burn), incorporates a chip inside the detonator.
Back in the mid-1970s, Orica (and indeed back through ICI and ICI affiliates which were the predecessors of the Orica group) began development of an electronic blasting system to try and improve on the accuracy being achieved at the time with pyrotechnic delays.
1% of program delay -- comparable to 1 - 10% for standard pyrotechnic delays, or an order of magnitude improvement.
For example, a pyrotechnic delay
with a nominal 500-millisecond (ms) delay might have a coefficient of variance of 1% to 2%, which translates into (15 ms for three standard deviations or a range of 30 ms, which may be unacceptable in production blasting situations," said Watson.