Datum Electronics Series 420 Marine Torsionmeter System provides an accurate tool to assess and monitor propeller shafts on ships by measuring shaft speed, torque and power. This Torsionmeter System was designed specifically for use on the Royal Navy Hunt and Sandown Class Vessels.
DEFSTAN Specifications
The above Marine Torsionmeter System had to be approved and conform to Royal Navy standards. The Series 420 system has been through a rigorous MOD testing programme for use on board Royal Navy Vessels. The Series 420 has been tested and verified in a number of marine conditions including: Shock & Vibration, Heat & Hummidity, Salt Atmosphere and Water Ingress. It is the ultimate system for the most harsh of environments:
DEFSTAN 59-41, 61-5, 08-123 (NES 1004)
Single or Dual Shaft Measurement
The Datum Electronics Series 420 Torsionmeter System can either be a dual or a single shaft system to provide highly accurate non-contact torque measurement of shaft torque, speed and power.
System Setup
The Series 420 Marine Torsionmeter System includes a shaft Unit which is fitted to the ship shaft to measure torsional strain and rotational speed. A separate stator unit is then fixed inline with the shaft and transmits the data off shaft to the control unit.
A Control Unit to provide power to, and take data from, the shaft units, to calculate calibrated torque and shaft power (as a function of measured torque & speed). The Control Unit also records & displays accumulated running hours for each shaft.
An optional Remote Display Unit to display, Torque, Rotational Speed (and direction ‘AHEAD’ or ‘ASTERN’) and Calculated Power from Both Shafts.
Marine Torsionmeter Shaft Specifications
The Series 420 Marine Torsionmeter System fits ship shaft diameters between (160mm - 1100mm). The shaft installation comprises a standard stator unit that provides power to the on-shaft electronics and conditions the output signals. The stator housings are manufactured to cater for a range of shaft sizes.
Size 1 - shafts 160mm – 250mm
Size 2 - shafts 250mm – 350mm
Size 3 - shafts 350mm – 500mm
Size 4 - shafts 500mm – 650mm
Size 5 - shafts 640mm – 800mm
Size 6 - Shafts 800mm – 1100mm
Marine Torsionmeter Installation
The Torsionmeter System has a shaft installation supplied as a rotor sub-assembly and a stator sub-assembly. The installation on to each shaft comprises a dual bridge strain gauge installation. The installation of the rotor is followed by the installation of the stator.
The rotor sub assembly is split into two halves and bolted over the strain gauge installation. The rotor houses the rotor electronics module, acts as a carrier for the rotor coil and physical protection for the strain gauges. To maximise the vibration tolerance between the shaft and the stator the stator should be centred about the shaft to a tolerance of +/-1mm, this will allow an additional vibration tolerance of +/-6mm.
On larger shafts this vibration tolerance is between +/- 2.5 to 3.5 shaft diameter. The Control Unit is supplied as a complete assembly; it requires four physical mounting points for easy installation and 9 off connection points. The optional Remote Display Units are supplied as a complete assembly, with four physical mounting points and 2 off connection points.
Accurate Measurement of Shaft Performance
The Datum Electronics Series 420 Marine Torsionmeter System accurately measures the on-shaft torque (kNm), speed of the shaft rotation (rpm) and the power (kW) that is going through the shaft. The data is transmitted from the shaft in a digital format that can be processed and scaled off-shaft. The data transmitted contains the torque level, the shaft speed and diagnostics data such as the on shaft voltage and power.
The System provides actual data on the power delivered that can be compared with the expected design performance, together with ongoing data, that will indicate any changes to this expected performance level. Condition monitoring of a system of this type is important to any modern day vessel. Being able to accurately measure and record the ships power and speed data can help towards determining equipment condition and efficiency. It’s a pro-active measure with the specific purpose of improving performance and efficiency through a ship transmission system.
Series 420 Marine Torsionmeter System
Data Sheet (Adobe Reader required)