Available from Control Logic, Schmersal has released a heavy-duty switch called the ‘HDS’ with a Performance Level to PL e and IECEx certification. The fourth generation sets to unite a range of functions into a single platform for the first time to make it easier to select, install and retrofit a vast range of applications. The modular design boasts high-level communications with Dupline, and a kit of various actuating elements available for conveyor belt, positioning, level and pull wire emergency stop control.
The basis of the new platform is the standardised enclosure concept, which is available in two versions: thermosetting resin (Duroplast) or grey cast-iron body. The Duroplast version is resistant to aggressive media such as in the agricultural industry for the processing of fertilisers, minerals and phosphates. As well as port logistics applications in loading and unloading operations where reliability paramount, plus a wide range of other applications. The robust grey cast iron version is more suitable to mining or bulk materials, handling industries and extraction.
Designed for the most challenging of conditions, Schmersal has thought about every angle in a practical sense. The complete series comprises a closed cover over the switching shaft, cams and switch contacts to prevent contamination from dust and dirt. Regardless of version, the contacts are attached to a central terminal block ensuring repetitive and efficient wiring process.
More importantly, all switches have switching elements with at least two positive break contacts in accordance with IEC 60947-5-1, Appendix K. Furthermore, when an external force is applied to the actuating elements the positive-locking-fit opens the switch contacts. A critical feature in the event of a malfunction to ensure any kind of contact material fatigue or welding is separated by force which would signal a stop state to the safety system.
In terms of environment, the protection class is IP66 and IP67 for use in extreme environmental conditions, with the option for IECex zone 1 or 21 installations. For a gas explosive hazard as a mixture of air and combustible gases, vapours or mists is likely to occur in normal operation occasionally, such as outside of an unvented petrol tank or in ventilated coal mine shaft. For dust explosive hazard with an atmosphere in the form of a cloud capable of producing an explosive concentration of dust mixed with air, such as in the food and beverage industries for handling flour, coffee, powered milk, sugar, grain, rice, or mining industries where coal and sulphur dust are identified.
The function of the switch is divided into two versions as either latching pull-wire switch (RS655/RS656), or the momentary position monitoring (BS655/BS656) switch. The series is designed around three main applications for Emergency stop, position and alignment:
- PULL-WIRE EMERGENCY STOP SWITCH
Purpose designed for Emergency stop shutdown on conveyor belts and industrial systems where the emergency stop function can be triggered at any point on the wire rope. The maximum length of wire of 100 m on both sides of the switch greatly reduces the number of pull-wire emergency stop switches, and therefore minimises costs. Ideal for long conveyors with low risks where the wire can be installed at waist height in front of the conveyor, which provides an emergency stop if someone walks or falls towards the conveyor, hence pulling the wire. The switch also includes wire breakage detection to ensure a reliable emergency-stop function. If actuated, two-sided pull-wire emergency stop switches latch in the emergency-stop position and can only be unlocked when the reset button is pulled out.
In conjunction with an appropriate safe signal processing unit or safe network, the pull-wire emergency stop switch can be used up to Performance Level PL e in safety applications. As a status display, the pull-wire emergency stop switch is equipped with a mechanical status indicator that is visible when triggered. The switch can be reset with the blue Reset button integrated into the lever and satisfy the requirements of international standards IEC 60947-5-5, ISO 13850 and EN 620.
In terms of communication, Schmersal offers the integrated DuplineSafe® network solution that enables rapid and precise diagnostic, pre-wired normally-closed contacts and Dupline® connection terminals in/out up to 4 mm2. Dupline® is an industry standard 2 wire bus, that allows for connecting numerous switches and other equipment along one daisy chain cable, up to 10km. This negates the need to wire each switch individually to meet the necessary safety level and is especially cost-effective solution for long conveyor applications in resources industries where conveyors are typically in the tens of km’s in length.
- Position monitoring of moving parts on machines and systems
The standard switch model combined with a range of actuation elements offers a flexible means to detect the position and to monitor moving parts on rail-bound cranes, machinery, and plants. The standard switch includes an adjustment wheel on the switching mechanism, whereby the user can adjust the pre-set switching points between an angle of 10° and 35° angle. This greatly allows fine tuning the switch to suit the application at hand, but also reduces the need for numerous versions of the same switch. This lowers the effort required for storage, training and increases availability and commonality. Typical application areas include emergency-stop deactivation, end position monitoring in steel making and level monitoring in material silos.
- Alignment monitoring on conveyor belts (belt misalignment)
Belt alignment switches monitor belt alignment in the transport of bulk materials in mines, quarries, shipping ports and processing plants. The switches are typically arranged in pairs on either side of the transported material, close to the drive rollers and pulleys. In the event of position deviations of the conveyor belt, a staggered signal is generated as a pre-warning or to shut off the conveyor belt. This helps to prevent unwanted downtime because of belt drift and consequently rips and tears. Considering a conveyor belt costs $200 per metre, a 20-kilometre conveyor (40-kilometre belting) is an investment of $8 million, which by any accounting measure a Schmersal belt alignment switch with three Stainless steel levers to choose from, is an essential device to protect resource operations and significant conveyor belt investment.
Building your desired switch is a modular approach. First, you’ll need to select the base material and function, the switch elements includes either snap or slow action with the choice of 2 or 3 normally closed and normally open contacts. So that a total of either 4 or 6 contacts. Next, is an indication lamp on the top for local display of switch state, with a selection of 24VAC to 230VAC to choose from.
Finally, the actuating levers, that affix to the switch on a gear axel. This means the lever can be positioned in 10 different angle positions to get the best alignment for the application.
All switchgear satisfies the requirements of a safety switch, plus the HDS platform has a range of international approvals, including CE (Europa), UL (USA), CCC (China), EAC (Russia), Ex, IECEx (explosion protection, international) and INMETRO (Brazil, South America).
For more information contact Control Logic on 1800 557 705 or email our sales team at [email protected].
About Control Logic
Part of the IPD Group, Control Logic is one of Australia’s leading suppliers of industrial, electrical and automation products, services and solutions.
