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Elevators

This is a very common converter application. However, it requires extremely reliable input about the actual demand of the elevator motor. Most such elevators used in new construction in apartments, schools, churches, and for ADA retrofit applications are hydraulic. From the phase converter perspective this is simply a straightforward hydraulic pump application.

Kay Industries always recommends a rotary converter with automatic controls for elevators. This is because elevators by nature are subjected to many starts and stops and can run empty or fully loaded. A rotary converter is widely preferred over a static type because the rotary has far superior reliability over repeated start cycles and better performance over wide load variations.

The typical operating sequence for a converter operating an elevator is:

1. The converter starts upon executing the elevator call button
2. The converter starts in 2-5 seconds
3. A time delay relay in the converter closes an output contact
4. The output contact signals the elevator controller to start the motor
5. Another timer keeps the converter running for an adjustable period of several minutes after the elevator shuts down. This feature allows for the fact that elevator operations have a tendency to cluster and thus eliminates the need to restart the converter for closely spaced operations.

Critical Selection and Application Criteria:

Some brands of elevator motors carry horsepower ratings that are not consistent with national electric code tables for their full load current. For example a 20 HP motor may be represented as drawing 65 amps at full load. This current rating is actually closer to 25 HP than 20 HP. It is strongly recommended that the converter be sized for the HP equivalent of the full load amps rather than the stated motor HP.

Some elevator controllers include soft starters. A converter by nature provides a soft-start to a motor. We recommend across-the-line starting for elevator motors running on converters.