SURFACE BLASTING SYSTEM
Apparatus is provided for activating a plurality of groups of electrical loads, such as electrical detonators used in blasting, after respective time delays. The apparatus comprises a master control unit which generates master control signals to initiate timing out of delay devices associated with each load. The apparatus further includes several auxiliary control units which are connectable to the master control unit. Each auxiliary control unit is adapted to control a respective group of remote electrical delay devices with associated electrical loads. Each auxiliary control unit includes local control means for generating local control signals from the master control signals which are synchronised with the local control signals of other auxiliary control units, for initiating operation of the delay devices, so that a large blast can be carried out in a perfectly synchronised manner. The master control unit may transmit master programming signals to the auxiliary control units, which each program the electrical delay devices of their respective group. Synchronisation of the local control signals can be achieved in a number of different ways. A method of activating a plurality of groups of electrical loads is also described.