The AC drives manufacturer Vacon has developed an ATEX-certified thermistor input which is fully integrated in the drive. Certified and compliant with ATEX 94/9/EC, the integrated thermistor input is specially designed for the temperature supervision of motors that are placed in potentially hazardous areas.
In contrast to a typical system with a separate thermistor relay and contactor, a thermistor input can be fully integrated in the Vacon NXP drive. This unique feature simplifies the use of drives together with Ex motors, i.e. motors that are designed and certified for use in potentially explosive environments. If overtemperature is detected, the drive immediately stops feeding energy to the motor and thus further heating of the motor is avoided. As no external components are needed, the cabling is kept to a minimum. This improves reliability and saves both space and costs.
"As usual, designing an ATEX-certified thermistor input started from a customer need," says Mr Heikki Hiltunen, Executive Vice President, Vacon. Explosive atmospheres where supervision of motor temperatures is required are widely found in the chemical, petrochemical, marine, metal, mechanical woodworking, mining and oil drilling industries.
The thermistor input is available for the Vacon NXP drives in the power range of 0.75 kW - 5 MW in voltages 380-500 V and 525-690 V. This function is now certified to comply with the ATEX requirements. "However, the drives as such cannot be placed in a hazardous area," emphasizes Mr Hiltunen.
The ATEX directive 94/9/EC is about equipment and protective systems, intended to be used in potentially explosive environments. Named after the French words "ATmosphere EXplosible", the directive requires that all electrical and electronic devices installed in potentially explosive environments meet stringent and identical standards throughout the European Union. Environment can be potentially explosive due to gas or dust.
Vacon Group was founded in 1993 for one purpose only: to create, develop and provide AC drives worldwide. Our ambition is to meet the most demanding needs of customers looking for the ultimate in performance, ease of use and reliability. Vacon offers AC drives in the power range of 0.25 kW...5 MW. In 2005, the Group revenues totalled EUR 149.9 million.
