Smoother and more reliable motor control
January 2001
PLCs, DCSs & Controllers
Danfoss says that increasing numbers of engineers are turning to Cl-tronic soft starters for smoother, more reliable motor control. This device has proven to be a cost-effective way of eliminating the starting torque surge and significantly reducing inrush currents.
Technically advanced, the unit is easy to install and covers power ranges up to 18,5 kW. With a few adjustments, the MCI soft starters can accommodate most applications. Ramp-up and ramp-down times, together with the initial torque, are accurately but easily adjusted. For applications demanding a high breakaway torque, a special 'kick-start' feature can be activated.
When a ramp-down function is not sufficient, a brake is needed. The MCI 25B was developed for this type of application. Apart from the normal soft starting functions, the MCI 25B is equipped with an adjustable DC injection brake and a unique slow speed function. The brake is equipped with automatic stop detection that will safely bring the motor to a complete stop.
High inrush current is an inherent problem with most compressors. A star/delta solution is often unsatisfactory because of the high torque requirements. The MCI controller is good for this application, as the adjustable initial torque setting allows a smooth start on most compressors. On hermetic compressors it is essential that they reach full speed within a very short time. This is also possible; measurements show that soft-starting a compressor with only a 0,6 s ramp-up time still reduces the inrush current by approximately 50%.
Fans are another popular application for MCI soft starters. The smooth start eliminates belt squeal and prevents premature wear. On a typical cooling tower this reduces maintenance costs substantially. OEMs reduce the number of belts required on belt-driven machines also resulting in significant cost savings.
The MCI range of soft starters provides cost-effective solutions for a wide range of applications, as do the other products in the Cl-tronic portfolio: motor contractors and reversing contractors, analog power controllers and electronic contractors.
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