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Rotating torquemeter

The dynamic torque measurement is done by means of dynamic or rotating torquemeter . CAPTRONIC offers to supply a digital telemetry system, including a transmitter encapsulated in a miniature housing (to protect from centripetal loads or vibrations), for the client to install on the shaft.
 
The inductively powered system comprises:
• Single channel high-speed telemetry transmitter (rotating shaft mounted), conditioning the full-bridge strain gauge;
telemetry transmitter smodule rotating shaft
Transmitter module
Dimensions : 37x21x5,5 mm
Mass of the module = 8 grams
• Inductive power rectifier (rotating shaft mounted), collecting power from the antenna wrapped around the insulating former and providing a regulated supply to the telemetry transmitter.
 
• Inductive power oscillator ground station (stationary) with ferrite excitation yoke (C-core);
 
• Single-channel high-speed telemetry receiver (stationary), to output the telemetry signal.
 
telemetry receiver module torque measurement
 
The strain gauge signal will be conditioned and sampled at a maximum rate of up to 30 kHz, allowing 15 kHz bandwidth, with 24-bit equivalent resolution (using a 16-bit ADC with 256 x analogue pre-amplification of the strain gauge).
Analogue pre-amplification (gain) is to be specified by the customer, based on maximum expected bridge-level output. The system supports a full-bridge strain gauge of any resistance (eg 120 Ohm, 350 Ohm, 1 kOhm).
The transmitter accepts a Hall-effect Tacho sensor to provide a 1 PPR output, if required.
 
The supplied transceiver will offer analogue outputs (0-5 V) to be interfaced to a third-party acquisition unit.
 A USB receiver, allowing streaming data to hard drive, is also available as a separate option.
It is advisable to use balancing resistors on the transmitter to perform balancing at bridge level before amplification and sampling. A multi-mode (dual colour) LED on the receiver indicates transmitter presence and gives health and warning indicators (such as low power).
 
All rotating electronics parts are encapsulated to protect against mechanical shock and vibration (capable of withstanding 10,000 g mechanical shock acceleration). The system is designed to operate within the standard commercial temperature range of -20 to +85 °C.
 
If an inductive power supply is required, CAPTRONIC will design and manufacture a suitable inductive loop former to be mounted to the shaft.
 
rotating shaft torque meausrement
Figure1 : Torque measurement on rotating shaft
Figure 1 shows a previously supplied system of similar specification.
The brown (Tufnol) clamped disc on the left of the shaft houses the inductive power rectifier, with the yellow wrapped wire serving as the pick-up antenna. Regulated power is then fed to the telemetry transmitter, housed in the black disc to the right hand side.
 
This black disc also covers and protects the strain gauge. This ‘two-disc’ approach separates the sensitive strain gauge output from the high-voltage, high-frequency inductive supply which may otherwise cause interference. It is highly recommended to use this approach if space permits.
 
Alternatively a more complex single disc can be manufactured, which screens the receiver from the rectifier compartment. It is also noted that tuning the inductive power supply (which requires fitting tuning capacitors and measuring the output voltage) can be a complex operation, and this task can only be performed once the system is installed on the shaft. It is therefore highly recommended that the shafts be sent to our premises for tuning and commissioning.
 
Alternatively, a technician can be sent to the customer’s site to provide on-site assistance with this task at our standard rates.