Rock 541™ — API 541 motors for oil and gas and chemical industries

Description

Rock 541™ — induction motors built to the requirements of the API 541 standard for oil refining, petrochemical and chemical plants. Each motor is designed for a specific application, combining solutions accumulated over more than 100 years with modern design methods: concurrent engineering, three-dimensional solid modelling, finite element analysis and a product data management system. Motors are produced in all API 541 configurations and can meet the requirements for the lowest vibration levels. All general-purpose Rock 541 motors provide: continuous operation or operation after a long shutdown in petrochemical production conditions; a winding retention system designed for well over 5000 full-voltage starts; a 'three cold starts, two hot starts' mode; solid heat-treated forged shafts for two-pole machines; induction brazing of the bars to the shorting rings up to about 10,000 hp; stainless steel screens; non-sparking fans; core electrical steel not lower than class C5. For all motors the following are available: reduced noise level, explosion-proof designs, ultrasonic inspection of shaft forgings, unbalance response calculation with damping, three-plane rotor balancing, and tests with a half coupling and a moment-of-inertia simulator. A number of solutions exceed API 541 requirements: instead of a single stator impregnation, at least two complete vacuum-pressure impregnations with epoxy varnish coating are performed; the squirrel cage is made only of copper or copper alloy, with no aluminum; shorting rings have no circumferential joints at any speed; all motors with sleeve bearings use spherical self-aligning bearing shells and non-metallic floating self-aligning shaft seals.

Stator windings use the proprietary Thermalastic® insulation system: mica insulation of the form-wound coils, vacuum-pressure impregnation of the wound and connected stator with solvent-free epoxy resin, and oven curing; the cycle is repeated to eliminate voids that cause corona. The insulation withstands long-term voltage stress, moisture, contamination, thermal cycling and chemical effects. The frame is a welded box construction, and the rotor is reinforced with a copper cage. Applications: centrifugal compressors, pumps, fans and other critical drives at refineries, gas processing and chemical plants. Large machines are manufactured and tested at the plant in Round Rock, Texas, USA, which has produced large DC motors since 1976, AC induction motors since 1977 and synchronous motors since 1978.

Technical specifications