APPLICATIONS OVERVIEW 19 20 APPLICATIONS OVERVIEW
Figure 9 shows a more complex zone control system. Two machines are linked together by a common industrial conveyor system. The conveyor feeds pallet loads into and out of each potentially dangerous machine. The machinery system is surrounded by fixed fences with electrically interlocked gates giving personnel access to the machine in zone 1 and the machine in zone 2. Safety light curtains safeguard the conveyor feed areas. Figure 9 The electrical safety output contacts of light curtain (LC1) are connected to the ‘STOP’ circuits of the machine shown in zone 1. The safety output contacts of light curtain (LC2) are connected to the ‘STOP’ circuits of themachines in zone 1 and zone 2. The electrical safety output contacts of light curtain (LC3) are connected to the ‘STOP’ circuits of the machine shown in zone 2.The light curtain (LC1), at the infeed to zone 1, uses a parallel-beammuting system with the light curtain (LC3) at the outfeed from zone 2 providing an OUTFEED ONLY cross-beam muting system.The light curtain (LC2) positioned between zone 1 and zone 2 utilises control signals from the access gates and additional output signals from light curtains (LC1 and LC3) for muting and un-muting the light curtain.With both access gates closed and locked and light curtains LC1 and LC3 both active then (LC2) will be in a muted condition, allowing products to flow freely through the machine complex, but would instantaneously shut-down all machinery motion should a person attempt to gain access into the danger zones. If either of the access gates to zone 1 or zone 2 are opened then light curtain (LC2) will activate (turn-on). Similarly, if either light curtains (LC1 or LC3) become tripped then again (LC2) will become active.Interruption of the light curtain (LC2) will stop all machinery operation in both zones. The system described offers total safeguarding at both zones while allowing the flexibility of industrial safe access to personnel into one of the zones while allowing continuous operation of the machinery in the other zone. For example. An operator needs to enter zone 2 to remove a damaged package on the pallet. He gains access to the area via the interlocked gate at zone 2. Unlocking the gate will automatically stop the machine in zone 2 and activates light curtain (LC2). He can now enter zone 2 in complete safety even while the machine in zone 1 is operating. Should he attempt to pass into zone 1, through light curtain (LC2), then the machinery in zone 1 will stop. 8000 SERIES8000 SERIES