BS ISO 14839-2 pdf download Mechanical vibration — Vibration of rotating machinery equipped with active magnetic bearings — Part 2: Evaluation of vibration
This part of ISO 14839 sets out general guidelines for measuring and evaluating rotating machinery equipped with active magnetic bearings (AMBs) with respect to the following two indices:
— shaft vibratory displacement measured at or close to the AMBs, and
— working current and voltage measured in magnetic coils or power supply amplifiers.
Both indices are measured under nominal operating conditions in house and/or on site. These guidelines are presented in terms of both steady-state running values of these indices and any magnitude changes which may occur in these steady-state operations.
This part of ISO 14839 is applicable to industrial rotating machines generating or consuming nominal power greater than 15 kW, and is not limited by size or operational rated speed (i.e. comprising turbo-compressors, turbo-pumps, steam turbines, turbo-generators, turbo-fans, electric drives and other rotors supported by AMBs). This part of ISO 14839 establishes the vibration, current and voltage evaluation of the rotating machinery equipped with AMBs, specified by a comparatively large power capacity as described above, excluding small- scale rotors such as turbo-molecular pumps, spindles and flywheels.
This part of ISO 14839 covers both AMB-equipped rigid rotors and AMB-equipped flexible rotors.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 7919-1, Mechanical vibration of non-reciprocating machines — Measurements on rotating shafts and
evaluation criteria —
Part 1: General guidelines
3 Measurement and evaluation procedures
3.1 Description of rotor-AMB system
A typical rotor system supported by AMBs is illustrated in Figure 1. An AMB is located at each end of the shaft and includes an adjacent displacement transducer and an emergency (auxiliary) ball bearing. The axial AMB is omitted in this figure. The control network for driving the AMB device is shown in Figure 2. As shown in these figures, each displacement transducer detects the shaft journal position at the bearing locations and its signal is fed back to the controller. Deviation from the bearing centre is delivered to the controller. This controller might, for example, implement a proportional, integral and differential actions (PID) control algorithm. The controller drives the power amplifiers to supply the coil current. If the shaft moves downward, the upper electromagnetic coil is activated to lift the rotor upward by the magnetic force. Since, in this manner, the magnetic force acts upon the shaft so as to maintain the shaft at the neutral position inside the bearing, the AMB accomplishes both levitation and vibration control without mechanical contact.