Encoders for the elevators of the future: KCI 419 Dplus and LINA 200

The KCI 419 Dplus inductive elevator rotary encoder delivers far more than position feedback for motor control on traction elevators. It can also detect the brake stroke without additional microswitches and measure the brake temperature. The KCI 419 Dplus is therefore optimally suited for brake monitoring. Via the EnDat interface, it even provides diagnostic data to downstream electronics, which can then derive the brake status (released or engaged) and the level of brake wear.

The new KCI 419 Dplus not only offers greater availability and safety; it also significantly reduces the time and effort necessary for installation, cabling, adjustment, and maintenance. The following capabilities are integrated in this device:

• Motor feedback
• Brake release monitoring
• Wear indication data
• Temperature monitoring
• Online self-diagnostics
• Digital data transmission

By virtue of its direct proximity to the motor and brake, the KCI 419 Dplus rotary encoder for elevators also provides meaningful temperature monitoring data without the need for additional sensors. These temperature data can then be used to infer the presence of malfunctions.

Because all of these parameters are transmitted on a single cable via the purely digital EnDat 2.2 interface, overall system cabling is greatly simplified. Further benefits include improved remote monitoring and predictive maintenance capabilities.

In addition to these completely new innovations, the KCI 419 Dplus also includes all of the familiar strengths of classic rotary encoders from HEIDENHAIN. Its inductive scanning method is highly immune to contamination and vibration, and is renowned for its operational reliability.

Envision an elevator car not pulled by cables while capable of both vertical and horizontal travel—HEIDENHAIN is offering the encoder technology to make this possible: the LINA 200 absolute inductive linear encoder. It consists of two tracks with different signals periods, from which the absolute position value is then calculated.

A special feature of this scale is that the two tracks are not located in one plane; instead, they face each other. The resulting U-shaped scale allows the measuring standard to be scanned from two sides. At the same time, a double-wall design protects both the graduation and the scanning process from mechanical and electromagnetic interference. This structural configuration also combines maximum stiffness with low weight.

The LINA 200 thus delivers reliable, highly accurate position feedback for the cableless elevator’s motor control. Yet it also provides sufficiently wide tolerances for real-world mounting inside the elevator shaft and for the compensation of building displacement. At low speed, as well as during the deceleration and acceleration phases before and after a stop, the high-resolution position feedback (18 bits) at a measuring length of approximately 600 mm ensures very comfortable and gentle motion.

The scanning head signals of the LINA 200 are so robust and reproducible that the diagnostic values for signal quality defined in the EnDat protocol can also yield information about whether the guide rails are within tolerance. The LINA 200 thus serves not only as a linear encoder but also provides data for continuous diagnostics and condition monitoring of the larger mechanical system. As a result, lateral deviations during operation can be detected.

The high-accuracy position values are transmitted purely digitally to the subsequent electronics via the EnDat 2.2 interface. In this particular application, however, EnDat 2.2 provides another important and safety-relevant benefit pertaining to the strong magnetic fields that surround linear motors: the EnDat 2.2 interface features high electromagnetic compatibility and, unlike conventional analog signals, ensures reliable data transmission even in this kind of environment.

In the cableless elevators of the future, the change in direction from vertical to horizontal will be performed within the elevator shaft at rotational joints driven by high-powered torque motors. The position data required for controlling these motors will be provided by angle encoders such as the AMO WMK. Alternatively, exposed linear encoders such as the HEIDENHAIN LIC series can be used as well.