Extreme Motor Performance

DN Staff

July 20, 2009

2 Min Read
Extreme Motor Performance

Vacuum and radiation-hardened gear motors and resolvers are utilized bythe Australian Nuclear Science and Technology Organization (ANSTO) on researchinstruments at the organization's Bragg Institute research facility. To performreliably in the extreme conditions, all the organic materials used in thestandard motor design needed to be evaluated against specific radiation doserequirements.

Everything from the magnets and bearingsto the glue and lubricants was analyzed. Radiation-resistant materials were substituted,if required, to withstand the radiation generated to test materials andequipment. Teflon motor lead wires, for example, don't perform well underradiation and were replaced with a specialized material called peek to maintainhigh system reliability.

In the final design, specialty motors andresolvers from Empire Magneticsare being used in ANSTO's TAIPAN and SIKA 3-axis spectrometers, its PELICANcold-neutron time-of-flight spectrometer and the QUOKKA small angle scatteringinstrument. These instruments perform neutron scattering, and are essentiallyscientific research tools for physicists, engineers and chemists. Theinstruments allow the atomic, electronic, and magnetic structure of materialsto be analyzed on a resolution and depth not possible with any otherinstruments.

The TAIPAN instrument is a triple axisinstrument used for measuring phonons or "solid state waves" which can givescientists insight into processes such as high temperature superconductivity.This instrument is closest to the core of the nuclear reactor and has a momentof inertia of 15,000 kgm2. High torque, high inertia motors areneeded to function in a radion environment with a high degree of reliabilityand quality.

In a nuclear research facility, all electricalcontrol components are subjected to extreme environmental conditions, includinggamma and neutron radiation. Components are embedded inside radiation shieldingthat is keyed together in large monolithic slabs. If a motor fails, the instrumentis shut down and engineers wait up to a week for the radiation to die down. Theradiation shielding is then removed; the motor is replaced; and the shielding iskeyed back together, a process that can take up to two weeks.

Empire Magnetics' radiation-hardened motorsare available with continuous output torque ranging from 15 to 400 inch-lb (1.7to 46 Nm) or momentary peak torque from 30 to 1000 inch-lb (3.4 to 113 Nm). Motorsare rated for a total standard accumulated dose of 2x108 rads (radiationabsorbed dose), with ratings to 1x109 rads available on a custom basis.

An anti-backlash, radiation-hardened resolver with gearing provides precision encoding in a radiation environment. Using a precision spring to eliminate backlash in the encoding system allows accurate values to be sent to the motion control system.

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