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E + Source Target Prototype Update and Data to date. Status Torque transducer / motor control data Accelerometers. Current Status. Local guarding frame has been built Awaiting confirmation of sheet thickness Still stuck at 60 rpm
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E+ Source Target PrototypeUpdate and Data to date • Status • Torque transducer / motor control data • Accelerometers
Current Status • Local guarding frame has been built • Awaiting confirmation of sheet thickness • Still stuck at 60 rpm • Initial work by Chris Nelson (RAL) agrees with Lisle Hagler (LLBL) rotordynamic and thermal stress analysis • We have spoken to Jim Rochford (RAL) about magnetic modeling simulations in Opera/Electra: we may be able to do this in-house very soon! • 4 thermal cameras operational • PC seems to be able to cope with picoscope, torque software and CTscope simultaneously • Accelerometer hardware trip completed
Motor Control Torque Transducer (T12)
Encoder and requested rpm (y) time (x) CT motor control feedback data Encoder ( 0 – 655320) : shown divided by 1000 on plot Wheel continues spinning after motor switched off ENCODER POSITION RPM
Torque and rpm (T12) Speed shows oscilliatory behaviour 60 rpm seems to be peak speed, not even average Speed tails off after motor switched off TORQUE Nm RPM
Blue – requested rpm, Red – rpm from torque transducer, Green – encoder, Black – torque (Nm)
Torque drives speed change (matched but slightly ahead in time) Tosc = 1 sec @ 60 rpm = 1 rev per sec ( x-scale = milliseconds ) Speed and Torque overlaid only for shape comparison purposes (not same scales) TORQUE SPEED
Rpm (calc) and encoder (ct) Rpm calculated from encoder position change and time Oscilliatory behaviour seen before not very clear
Blue – calculated rpm from encoder, Red – rpm from torque transducer Difficult to convincingly show agreement, too few data points from encoder
Speed = 30 rpm • Oscilliatory structure far less clear • Not obviously 2Hz as expected • Speed well short of 30 rpm • Too slow for torque transducer? • Calibration? RPM
Torque @ 30 rpm • Highly oscilliatory • Behaviour after motor switch off not the same as 60 rpm
Torque @ 30 rpm 3 seconds of data = 1 ½ revolutions Spokes(5) are equally spaced but large troughs(6) are too far apart in time to be spoke edges either Unsure of cause :- ball bearings in bearing housing / motor, no. coils / windings / magnets ?
Accelerometers One accelerometer on table (control) and one on bearing housing
Motor off: background noise This is a static plot but frequent fluctuations seen on short time scales, all frequencies Something loud at 450Hz? Air con? 100 Hz? (see next plot) Red: on table in personnel area Blue: on bearing in machine area
Motor on at 0 rpm: rumbles rumble seen @ 420 Hz + 525 Hz ? trough at 200Hz likely a short-term fluctuation
Motor at 60 rpm Entire spectrum gets louder Very difficult to pick out any particular enhanced frequencies ( i.e. Hz ~ rpm )
HBM measurement training day • Torque transducer is just a set of strain gauges on a shaft • The twist alters the resistance which is measured by wheatstone bridges • To achieve the highest levels of accuracy, temperature and initial stresses must be considered Makes solid metal rig seem like a wobbly structure!
Summary • Progress is being slowed up by safety considerations • Most DAQ is in place and data taking is happening • As always there are a few teething problems and unexpected results • Proprietary software is largely black-box plug-and-play… Easy to set-up but difficult to cater for specific requirements of the experiment