When performing maintenance, keep the workers safe by using Pilz’s key-in-pocket solution to stop an unexpected machine restart as long as employees are still in the risk zone.
In comparison with conventional lockout/tagout (LOTO) systems, maintenance safeguarding is implemented purely electronically via RFID keys with corresponding permissions. Mechanical interlocking devices and warning tags are thus not required.
The personal transponder key for the operator to the access permission system
The combination of the safety controller PSS 4000 and the access permission system PITreader ensures that a plant cannot be restarted until the last person has left the danger zone. Maintenance safeguarding is enabled via individually programmed RFID keys with corresponding permissions and a safe list in the controller. Operators use a personal transponder key to authenticate themselves on the safety gate via PITreader.
Their security ID is stored in a safe list in the Pilz controller PSS 4000. When the machine has stopped, it can be accessed to carry out work. The employee always keeps hold of the transponder (“key-in-pocket”). In order to put the plant back into operation, everyone must sign out via the PITreader after leaving the plant. This removes the security IDs from the safe list. Once the list is empty, the machine is enabled and can be put back into operation.
The maintenance safeguarding key-in-pocket solution function is implemented using function blocks/components in the Pilz controller PSS 4000 (PSSu PLC):
- The connection to the corresponding PITreader (up to 10 PITreader units can be managed in a safe list);
- The minimum permission required to sign in to the sign in list;
- The inputs for the LED pushbutton(s);
- The entry for the “sign out condition” (blind spot check). Where plants have no overall view, there is an additional “blind spot check” in accordance with EN ISO 13849-1 5.2.2. This requires a visual inspection of the plant in areas that are difficult to see. The machine can then be restarted;
- The outputs for “Enable (list empty)” and blind spot check.
An overview of the benefits:
- Authentication of personnel and safe restart protection against unintentional (machine) start;
- Certifications: PLd Cat. 3 in accordance with EN ISO 13849-1 and SIL CL2 in accordance with EN 62061;
- Full control and traceability of who has access to which machine; temporary permission is also possible;
- Up to 10 PITreader units can be managed in a safe list;
- Up to 20 people can access a machine at the same time;
- Considerably less expensive and more flexible than transfer systems made of metal;
- Simple blocking and reprogramming in the event that a transponder key is lost;
- Blind spot check in accordance with EN ISO 13849-1 5.2.2: The last person can be “forced” to acknowledge areas that are out of sight before the plant can be restarted;
- Authorised personnel can delete the safe list, “key list reset”;
- It is not necessary for people to exit the plant through the same gate by which it was entered;
- It is possible to show the safe list (people and telephone numbers for example) directly via the PASvisu.
