Product category:
Loadcells, Force Sensors and Torque Sensors
News Release from: Industrial Measurements | Subject: MT series torque transducer
Edited by the Engineeringtalk Editorial
Team on 26 July 2005
Torque transducer survives maritime
duties
The latest version of the MT series torque transducer is fitted to vessels throughout the world, including the UK's own RNLI rescue vessels.
Almost 20 years ago, Industrial Measurements developed its first MT series torque transducer Responding to a need from ship's operators to closely monitor overall vessel performance, IML designed a rugged unit that could survive all the rigors of a marine environment, and still provide accurate torque measurement from the drive shaft of the ship, which in turn meant that power output and power consumption, could also be monitored
This article was originally published on Engineeringtalk on 14 Nov 2006 at 8.00am (UK)
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The new TLT torque transducer from Industrial Measurements is not the most accurate, not the fastest and not the cheapest in the world, but it's great value.
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The TB and TL torque transducers are designed for tool-testing applications but can be used in other situations.
Now, the latest version of the MT is fitted to vessels throughout the world, including the UK's own RNLI rescue vessels.
The system has many user benefits.
First, the use of a single stator coil for power transmission and data retrieval minimises alignment problems and the high frequency transmission enables large running gaps typically 10mm, can be accommodated thus avoiding any vibration problems.
Secondly, the 10kHz modulation signal can cater for bandwidths in excess of 200Hz, thus enabling torsional vibrations to be observed if required.
Thirdly, the rotating unit is simple in design and is easily fitted to various shafts.
Further reading
Torque measurement system copes with higher speeds
Retrofit torque measurement has become much more cost effective in recent years, and the latest system is designed to fit any shaft diameter from 100 to 250mm.
Portable torque analyser
IML's latest torque analyser, the DTM-1000, is the most portable unit the company have ever produced.
Brief history of torque measurement
Industrial Measurements explains the development of industrial torque measurements from a wrench to a handheld instrument in two decades.
The modular arrangement of the electronics allows easy replacement in the unlikely event of a failure occurring.
Fourthly, system calibration can be checked from any remote location, providing the shaft is stationary and not seeing torque.
Finally, the torque speed and power systems are totally contained within the stator housing.
Digital or analogue meters can be located virtually anywhere within the ship.
Frequency outputs are particularly useful and can be tailored to suit different performance monitors.
At the heart of the system are the strain gauges.
These are carefully bonded to the shaft at 45 degrees, and wired in a Wheatstone bridge configuration.
This ensures that only the effects of torque are measured.
Any bending or tensile stresses in the shaft will induce the same change in each gauge, thus cancelling the effect.
the signal from the Wheatsone bridge is therefore a direct linear indication of the torque in the shaft.
Initial range setting of the equipment is calculated knowing the diameters and shear modulus of the shaft.
Simulated torque levels can be induced into the system by offsetting the Wheatstone bridge with a known external resistor, and as the system is linear, the calibration over the measuring range is confirmed.
The frequency modulated signal and power transfer system developed by IML's Marine Division, has been used successfully for many years and it's proven reliability is known by many of the world's leading fleet operators.
The rotating unit consists of a rotor coil and electronics module, within which there is the straingauge amplifier, voltage to frequency decoder and regulated DC supply.
The output from the electronics module is a frequency modulated signal within the range 5 to 15kHz, given a maximum frequency shift of +/-5kHz.
This is fed to the rotor coil and transmitted across the air gap to the stator coil.
The stationary components consist of a stator housing, stator coil, speed pick up and decoding electronics.
From this unit, a variety of outputs are directly available, eg 4-20mA, 0-10V or frequency only, all accessed via 2.5mm rail mounted terminals.
A separate cabinet can be provided to house meters, but it is more usual for the DIN standard units to be incorporated into existing fascia panels.
A calibration check must be performed with shaft stationery and no torque applied.
This is possible by pressing a button mounted anywhere away from the shaft.
This momentarily interrupts the power supply to the rotating electronics, which is recognised, and a shunt calibration resistor is automatically introduced across the strain gauge bridge, for a predetermined period of time (approximately 20s).
During this time a crystal controlled oscillator can be switched into the system, thus providing a calibration check for speed and power.
Use of the MT series torque transducer, is by no means limited to marine applications and indeed new uses for this versatile unit develop on an almost daily basis.
40 or so are fitted to steel rolling mills around the world and there is even one at a clay mixing works in Cornwall.
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