TÜV Certification for Ex P Motors
The test specimen, a compressor motor for the petroleum industry, underwent a gas displacement test (of the air purge system), leak test and pressure test. The German technical inspection service TÜV Nord comprehensively tested and certified the construction method. To win the approval, the manufacturer had to prove its ability to control the purging air flow for all its relevant motor series in such a way that no gas pockets remain inside the motor casing. Menzel can apply this manufacturing procedure to stock motors in a wide output range and is thus able to flexibly and quickly provide competitively priced Ex p motors featuring the product categories 2G and 3G. Pressurised motor construction is typically suitable for squirrel-cage motors from 400mm shaft height. It is available for all voltage ranges and with air-to-air or airto- water heat exchangers (cooling types IC 611, IC 616 or IC 81W).
An air-purge system allows potentially flammable gases to be removed from the motor frame before the motor is started and maintains a constant positive pressure during operation to prevent the ingress of explosive gases. The terminal boxes feature the ignition protection type Ex eb (increased safety).
Plant operators often face the challenge of not being able to find suitable replacements for obsolete motors. The choice of explosion-proof drive systems, in particular, is limited. Up until now, the only alternative was to buy a standard motor with the required explosion-protection rating and adapt the installation site and/or driven machine, sometimes at considerable time and expense. Menzel's certification for the construction and manufacture of protected motors now gives customers more freedom of choice and flexibility. The German manufacturer specialising in large electric motors always configures motors for individual application and installation conditions. Likewise, the air purge system for pressurised motors is individually calculated and implemented, ensuring that the finished systems meet the highest safety standards.
For one petrochemical company, Menzel has recently manufactured an Ex p compressor motor based on its MEBKSL series, which matches the original motor in all mechanical and electrical interfaces. The compressor motor – for use in an oil refinery – is labelled II 3G Ex pzc ec ic IIC T3 Gc for zone 2. It has a rated voltage of 6000V and a rated output of 1635kW. Before shipping, the motor was rigorously tested in the company's in-house test facility, including load and type testing.
Menzel's Ex p motors were named the Product of the Year in the 2023 AEMT Awards.