Reliable encoders for safe and accurate wind turbine applications
Meß und Regeltechnik, Messsysteme, Windenergieanlagen
Geared limit switches are safety and control systems intended to monitor both the pitch of the blades and the jaw of the nacelle in the wind turbines. They consists of a pinion gear, mechanical cams and encoder assembly and are designed both to limit the rotary travels (using the cams) and to give precise position, speed and acceleration feedback (thanks to the encoder). Thus they allow to always keep the blades and the nacelle in the most efficient and safe position and to provide the highest security level by warning in case of adverse weather conditions. This guarantees the maximum output and performance of the wind turbine and also reduces the overall fatigue loads on rotor, tower and foundation. Yaw control also prevents the cables from twisting inside the tower by controlling the number of turns of the nacelle.
Geared limit switches integrate incremental and absolute encoders for exact position, speed and acceleration control of the blades and the nacelle. Most compact encoders can be installed inside the housing thus reducing the overall equipment footprint. However integration into bus interface installations requires bigger-size encoders, so limit switch models with extended shaft and external absolute encoder are further available.
Because of their field of application (wind turbines turn out to be one of the most demanding testing grounds for innovative technologies), encoders in geared limit switches feature high-quality and rugged components and state-of-the-art encapsulation to always ensure dependable, efficient and unlimited operation. They must strive against the harshest weather conditions (wind, water, salt, UV rays …) in both freezing cold and sweltering climates yet demonstrate durability and reliability at all times, the whole lifetime of installation.
Lika Electronic offers customized solutions for each application in the geared limit switches and a very wide range of encoders and configurations to meet the most diverse customer requirements: incremental and absolute encoders, optical and magnetic scanning, hollow and solid shaft mechanical flanges with multiple mounting variants, standard electrical and bus interfaces, a variety of connections.
Miniature optical I41 and magnetic MI36 incremental encoders can be easily integrated inside the limit switch housing thanks to the ultra-compact enclosure (Ø 40 / 36 mm) with high IP protection rate (IP66/IP67). I41 is one of the most popular and widely appreciated incremental encoders from Lika. This optical encoder produces digital (square wave) signals with complementary and zero signals (AB0, /AB0) and supports various types of incremental electrical interfaces such as NPN, PNP, Push-Pull, Line Driver and Universal circuit. Output resolutions are available up to 5000 ppr. MI36 is the affordable choice offering magnetic scanning technology in a 36-mm diameter enclosure. Along with the 6-mm only solid shaft it ensures a perfect fitting in limited space and high resistance against shocks and humidity. Square wave signals (A, B, 0 and inverted) are available through NPN, Push-Pull and Line Driver standard circuits.
For the most sophisticated in-house installations, high-resolution multiturn absolute encoders can be provided. They ensure the greatest accuracy and real position availability also after power outage. MMC36 is the 36-mm diameter flange encoder with magnetic scanning and an overall 27-bit multiturn resolution (12 x 15 bits). It is fitted with a 6-mm diameter blind hollow shaft to reduce the outer dimensions. Synchronous serial interface (SSI) allows for a RS-422-based communication through six wires only and Gray or Binary codes.
Despite its small size, AMC36 is the superior encoder encompassing increased security and operation performances for wind turbines. It ensures IP67-rated protection (IP65 at shaft side) and unparalleled resistance to large temperature fluctuations (up to -40°C +100°C / -40°F +212°F). AMC36 offers refined optoelectronic and optimized signal processing derived from the highest (and yet biggest) Hx58 series. This yields an outstanding and reliable encoder able to attain high resolutions up to19 bits singleturn (524288 counts per rev.) and up to 12 bits multiturn (4096 rev.) and produce impressive accuracy even at highest speeds coming up to ± 0,01° (± 36 arc seconds) at 16-bit resolution. AMC36 is offered with synchronous serial interface (SSI) and all-digital BISS-C interface for high operating speeds, improved protection against electromagnetic interference (EMI) and enhanced bi-directional communication for subsequent controllers.
As stated, geared limit switches are also available with extended shaft for the external installation of absolute encoders. This gives the opportunity of expanding freedom of choice to a wide range of absolute encoders in the industry standard 58-mm diameter flange. Furthermore encoders with most common industrial fieldbus interfaces (EtherCAT, Profibus, CANopen, DeviceNET, Modbus) can be installed while maintaining a remarkably compact size.
HMCT is a high-performance multiturn encoder. Mechanically it affords standard 58-mm flange diameter housing with IP65 protection rate and through hollow shaft (Ø 14, 15 mm). It boasts high resolution up to 28 bits (16 x 12 bits) with additional incremental track and employs optical technology, thus it is insensitive to magnetic fields and does not require batteries. SSI and BISS-C serial interfaces allow for safe and interference-free transmission over long distances. To further increase operational performance and security it features an additional incremental track supplied in either sinusoidal or Push-Pull or Line Driver format.
EMC58 series and HMC58 series are the top solutions for cutting edge installations. They come in a very extensive variety of models, interfaces and configurations to successfully fulfill almost any requirement. EMC58 series is offered in a rugged housing with superior opto-electronics for dependable enduring service. Its mechanical properties along with the excellent encapsulation are designed to ensure robustness and durability even under the harshest operating conditions and provide IP67-rated protection and extended operating temperature range (up to -40°C +100°C / -40°F +212°F). Resolution is 13-bit singleturn and 14-bit multiturn; while output circuits are either serial SSI or Push-Pull parallel with additional incremental track. Modbus fieldbus interface will be available by the end of the year. In addition EMC58 PA is the fully programmable encoder with software-selectable voltage/current analogue outputs (0/5V, 0/10V, -5/+5V, -10/+10V, 4/20mA, 0/24mA, 4/24mA) suitable to replace outdated potentiometers while adding enhanced features. HMC58 series is the first choice for demanding limit switches. It has been devised for applications that require high resolution and great accuracy and is offered in 30-bit multi-turn version (16-bit single-turn + 14-bit multi-turn). HMC58 encoders can be supplied with either parallel and serial (SSI, BiSS) output circuits or a great variety of industrial fieldbus interfaces: EtherCAT, CANopen, Profibus, DeviceNet (and even Modbus soon). Fieldbus technology allows for bi-directional data transmission, enhanced programmability and comprehensive diagnostic information and further permits to simplify and standardize installation thus reducing the risk of errors and even costs. Today HMC58 encoder is also available in fully programmable version to maximize customization and flexibility and always match any unique demands. HMC58 PA offers impressive high resolution (singleturn up to 18 bits, multiturn up to 14 bits, configurable as needed) with either SSI serial or bit parallel programmable interfaces.
, Encoder Absolute
, Encoder Incremental
, Meß und Regeltechnik