The MAGNADET electric initiation system

CIM Bulletin, Vol. 75, No. 847, 1982

W.B. MORREY, Group Manager, Technical Services, C-I-L Inc., Explosives Division, Willowdale, Ontario

In recent years, the major effort in detonator development has been concentrated on "non-electric" systems. Existing types all involve some form of explosive reaction to transfer ignition energy from outside the borehole to the pyrotechnic delay element contained within the detonator. These may be based on low-energy detonating cords having grained or plasticized explosive cores, shock tube energy transmission principals and explosive gas ignition systems. Each has properties of internal and external effects not present in electric conductors. The MAGNADET System introduces transformer coupling into electric blasting circuits. Safety features with respect to current leakage, stray currents of AC or DC source, electrostatic energy and radio-frequency radiation are comparable to "non-electric" systems, with advantages in simplicity, speed of hook-up and range of application. The transformer device used is a small ferrite ring or toroid which is an integral part of each specialized detonator. The detonator legwires form the secondary side of the transformer winding. The primary side is a single wire loop common to all units within the circuit. Power is supplied from a frequency-tuned portable exploder with unique circuit-sensing features. The MAGNADET System is expected to have particular application to shaft sinking, raising and tunnelling where the protective features as well as speed and efficiency are critical factors. Applications of the 'MAGNA' booster in quarries, open pits and longhole deck charges offer control over vibration problems and elimination of surface noise.

Mots Clés: Magnadet, Initiation systems, Electric initiation systems, Blasting, Explosives, Detonators, Equipment, Transformer coupling.