ISO 16079-2:2020 pdf download – Condition monitoring and diagnostics of wind turbines — Part 2: Monitoring the drivetrain.
6.2 Descriptor types The descriptors are chosen based on the FMSA, which has provided a range of characteristics of specific faults. The most common descriptor types utilized for fault detection on the wind turbine drivetrain can be grouped as follows and derived from: — process parameters, — rotational speed, — vibration signals, — on-line oil analysis. The most common types are descriptors based upon vibration. Descriptors derived from process parameters such as rotational speed, wind speed and actual power are often used for compensating vibration-based measurements with respect to varying operating conditions. On-line oil debris measurements are used for detecting ferrous or non-ferrous particles in the oil. Figure 4 provides an example representation of the development of a mechanical failure.
6.3.2 Measurement of process parameter descriptors Process parameters are usually provided by: — 4-20 mA current loop signal: the 4-20 mA current loop is a common method of transmitting sensor information in many industrial process-monitoring applications. Transmitting sensor information via a current loop is particularly useful when the information must be sent to a remote location over long distances as the current loop is able to compensate for the voltage drop on the signal line. Many older wind turbine controllers can provide process parameters via a 4-20 mA output. — Voltage: some controllers provide a voltage signal proportional to the process parameter. However, this is not as common as the 4-20 mA current loop and not suited for transmitting signals over long distances. — Via LAN: process parameters may be acquired directly from the controller, or from the SCADA system via network protocols. High level protocols such as Modbus TCP/IP or OPC are very common. Some vendors have their own proprietary network protocols. 6.4 Measurement of rotational speed and descriptors based on rotational speed 6.4.1 General Measurement of the rotational speed is important for compensating other descriptors for variation in the rotational speed of the turbine. Many descriptors used for indicating failure modes on the drivetrain are speed dependent. This means that they are not measured at a certain fixed frequency but are measured at a frequency which is a certain ratio to the running speed. Gearbox descriptors such as the vibration level at the tooth meshing frequencies are typical examples of speed dependent descriptors. The raw speed signal can be stored as a time waveform, or as time stamps related to trigger points related to shaft position. (1/rev or n/rev). This data can be used for further processing of rotational- speed-related descriptors and in detailed diagnostic investigations.