Essen balancing pit – dynamic balancing of rotors A rotor’s balance essentially contributes to the service life of rotating machines. Unbalanced masses cause radial forces that strain bearings, casings, base plates, and not least foundations as well as building structures. Therefore, balancing of new and refitted rotors is an inherent part of the production and revision process. In this context we offer balancing solutions for a wide spectrum of rotors. Especially the potential of performing electrical measurements on rotors of electric machines during the balancing process considerably shortens throughput time. Figure 1: Low-pressure steam turbine rotor 27 tons/3,000 rpm Essen balancing pit Requirements for a balancing pit as to geometry, weight, and speed of rotors are very different. In order to optimally meet the requirements for turborotors (figure 1) and for rotors of electric machines (figure 2) in industrial applications, the Essen balancing pit (figure 3) was developed for rotors with the following specifications: Figure 2: Generator rotor 20 tons/3,000 rpm Rotor maximum weight approx. 32 t 1) maximum diameter approx. 3.1 m maximum length approx. 10.5 m 2) maximum speed 16,000 U / min maximum oil flow/bearing 375 l / min 3) maximum bearing journal diameter 400 mm maximum number of bearings 4 Figure 3: Essen balancing pit – crane and vacuum chamber 1) Higher weights after technical release 2) Longer rotors after technical release 3) Higher oil flows after technical release Answers for energy. Driver unit (figure 4) DC motor maximum power/speed 1.35 MW / 1,300 U / min direction of rotation left/right gear ratios: shift gear transmission 1:1/1:4 turbo gear transmission 1:3,5 shifting steps: low-speed high-speed Figure 4: Driver unit – direct current motor, shift gear, turbo gear 1:1/1:3.5 0 - 4,550 U / min 1:4 /1:3.5 0 - 16,000 U / min Main control room The main control room of the balancing pit (figure 5) comprises three operator terminals: vibration measurements and control process control electric measurements For the vibration measurement the Schenck-Systems CAB690 and Cabflex++ are used ensuring the following standards are met: International ISO 1940, ISO 11342 Standard Organization American Petroleum Institute Published by and copyright © 2008: Siemens AG Energy Sector Freyeslebenstrasse 1 91058 Erlangen, Germany Siemens Power Generation, Inc. 4400 Alafaya Trail Orlando, FL 32826-2399, USA For more information, contact our Customer Support Center. Phone:+49 180/524 70 00 Fax: +49 180/524 24 71 (Charges depending on provider) e-mail: [email protected] www.siemens.com/energy-support Order No. A96001-G90-B188-X-4A00 Printed in Germany 1386 J DA 0208 1. All rights reserved. Subject to change without prior notice. Printed on paper treated with chlorinefree bleach. Trademarks mentioned in this document are the property of Siemens AG, its affiliates, or their respective owners. The information in this document contains general descriptions of the technical options available, which may not apply in all cases. The required technical options should therefore be specified in the contract. API 617 In order to simulate realistic conditions, balancing at operating temperature may be carried out for rotors of electric machines by means of electric heating. For a final inspection, documents of frequency analyses, amplitude/phase diagrams, shaft vibration measurements are compiled in accordance with the respective guidelines. Figure 5: Main control room – vibration measurements, process control, electric measurements (f.l.t.r.) The interaction of the plant components (oil system, vacuum system/chamber, and driver unit) is controlled by a modern control circuitry system (WINCC) via pointand-click. For rotors of electric machines, the following electrical measurements may be carried during the balancing process: impedance measurement insulation resistance/high voltage testing ohmic resistance