Menzel Elektromotoren has been certified for the manufacture of large squirrel cage motors with type of protection Ex p pressurised enclosure for operation in Zone 1 hazardous areas in which an explosive gas-air mixture may occur during normal operation.
The test specimen, a compressor motor for the oil industry, was subjected to a gas displacement test (test of the air purging system), leak test and pressure test. The German TÜV Nord comprehensively tested and certified the design. For approval, the manufacturer had to prove that it is able to control the purge air flow for all its relevant motor series in such a way that no gas bubbles remain in the motor housing. Menzel can apply this manufacturing process to bearing motors in a wide performance range and is therefore able to offer cost-effective Ex p motors in product categories 2G and 3G flexibly and quickly. Pressure motor construction is typically suitable for squirrel cage motors from 400 mm shaft height. It is available for all voltage ranges and with air-to-air or air-to-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 to maintain 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 that they cannot 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 specializing in large electric motors always configures motors for the individual application and installation conditions. Likewise, the air purge system for pressurized motors is individually calculated and implemented, ensuring that the finished systems meet the highest safety standards.
For a 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 an oil refinery is labeled II 3G Ex pzc ec ic IIC T3 Gc for zone 2. It has a rated voltage of 6000 V and a rated output of 1635 kW. Before shipping, the motor was rigorously tested in the company's inhouse test facility, including load and type testing.
Menzel's Ex p motors were named the Product of the Year in the 2023 AEMT Awards.