The new ABB Ability™ Safety Plus for hoists, SIL 3 Hoist Monitor (SPHM) provides accurate safely limited speed, position control, acceleration and deceleration for a mine hoist, replacing a traditional system. It uses PROFINET/PROFIsafe safety encoders connected to the AC500-S safety PLC.
SPHM is implemented using safe function block diagrams and Structured Text programming languages. Using Structured Text in safety programming reduces the development time because you can be much more flexible when creating complex safety logic, such as safe supervision of the speed, position, acceleration and deceleration of the mine hoist.
In addition, fast safe floating-point calculations and trigonometric functions enable the mine hoist to run extremely quickly, often up to 20 meters per second (m/s). This significantly increases the mine hoist productivity without compromising on functional safety.
Using the PLC’s high-performance safety calculations when controlling a hoist running at 20 m/s, requires a very fast feedback from the encoder. This can be easily implemented using PROFINET/PROFIsafe communication between the safety encoder and AC500-S safety PLC.
The AC500-S included within SPHP protects against overspeed and over- or under-winding by running within safe limits set by the control system. Should the control system fail to stay within the pre-defined safe speed, position, acceleration or deceleration range, the Safety Plus Hoist Monitor triggers the safe machine stop and applies the mine hoist brakes to bring the hoist to a safe stop. For drum hoists, additional safety protection is provided for functions such as correct coiling supervision and clutch monitoring.