8537 EX switches with customisable high-performance features

02 November 2011

Introducing the 8537 series of safety switches, R. STAHL presents the latest generation of a product line that has proven itself for decades.

The switches feature a rotary handle which allows users to easily disconnect frequency-controlled motors from the mains without requiring a qualified electrician.

The series includes a wide range of models with extensive equipment and a range of new features. R. STAHL provides switch inserts for rated operational amperages of 12/16 A, 25 A, 40 A or 63/80 A. The easy-to-install modules can be adapted without any effort and retrofitted at any time. The units, which feature switching contacts with individual flameproof encapsulation, are available as 3-pole and 6-pole models with optional additional neutral wire terminals. Their motor switching capacity is AC 3 and AC 23 according to IEC/EN 60 947-3. An early break contact (≥20 ms) ensures safe motor disconnection even during frequency inverter operation.

Depending on the type, several NO/NC configurations are possible. Apart from forced opening of the main contacts, the switches also provide isolator features according to IEC/EN 60947-1.

In the “OFF” position, they can be secured by means of up to three padlocks. The load break switches are suitable for circuits in areas with hazardous gas or dust atmospheres (zones 1, 2, 21 and 22). The units are qualified for international use through ATEX/IECEx certifications and further explosion protection classifications for various regions (such as NEC, CTB, PESO and CQST Ex).

They can be used worldwide in maritime applications, e.g. in deep sea drilling platforms. Various types operate reliably even in extremely cold environments with temperatures low as -50°C, and are not affected by heat with maximum temperatures of +55°C or more, if required.

The switches are installed in shock-proof, corrosion-resistant IP66 enclosures. R. STAHL provides enclosures made from polyester resin and zinc-coated and painted sheet steel. Optionally, stainless steel types are available as special versions. The explosion-protected main switches with an upstream contact ensure that machine drives can be quickly and safely stopped for cleaning, maintenance or other service works. The safety switches, which have undergone continuous updates since their introduction, are traditional products which have been very much in demand for more than 30 years.