New speed monitoring modules and updated Configurator software (version 5.1.0) together result in additional monitoring functions for the Pilz PNOZmulti configurable safety controller. The first advantage of this development is that the PNOZmulti can now be used to monitor for broken shearpins on applications such as hoists.
Previously this might have required two encoders to be used - one on the motor and one on the driven shaft - to check for any speed differential, but the new speed monitoring modules can perform this function much more easily and at a lower cost. This is achieved by means of the usual encoder on the motor and a PNP sensor on the driven shaft. Software running on the PNOZmulti base unit analyses the signals from these two devices and initiates appropriate action in the event of a broken shearpin being detected.
One notable feature of this enhancement is that it allows the PNOZmulti and speed monitoring modules to be used for economical safety-related control systems conforming to the requirements of BS EN 954-1 Category 4.
The second new function added to the speed monitoring modules and software is a time delay for over-speed tripping on start-up. Some machines with high inertial loads will typically over-speed on start-up, before quickly settling back to their normal running speed. To avoid the speed monitor identifying this as a fault condition, the Configurator software can now be used to set an over-speed detection time delay following start-up.
Two versions of speed and standstill monitoring module are available for use with the PNOZmulti controller. While the PNOZ ms1p operates with a 5V encoder, the PNOZ ms2p accepts any incremental encoder input with a differential output from 0.5-30V, which gives machine designers a wider choice of encoders and makes it easier to upgrade existing machines on which encoders are already installed. Note that version 2 speed and monitoring modules must be used in order to perform the new functions, and the Configurator software must be version 5.1.0 or later.
A useful resource on the Pilz Automation Technology website is the list of current machinery safety standards. This has now been revised to reflect a number of recent updates and additions. To make it easy for users to find the information they need, the section is divided into four sub-sections covering: Machinery Safety Standards; CE Marking Guides; Published Documents; and Packaged Standards.
As well as the changes to bring the standards listing up to date, there is also now a link to the EC's New Approach website where there is a complete list of machinery safety standards harmonised to the Machinery Directive, 98/37/EC. This is particularly useful for designers and manufacturers of certain classes of machine for which Type C (product) standards are available in addition to Type A (basic) standards and Type B1 and B2 (group) standards.
Pilz is an official BSI Distributor, so any BSI document - whether or not it is listed on the Pilz website - can be ordered directly from Pilz.