Electricity + Control September 2017

round up PLANT MAINTENANCE, TEST + MEASUREMENT

Oscillating beam rig tests low frequency sensors Accelerometers and velocity meters are used to measure a wide range of frequencies, includ- ing low frequency vibrations found in building maintenance. They occur at less than 2 Hz, and can also be useful in monitoring bearing wear in cooling tower fans and gearboxes for example. To characterise the performance of its low frequency sensors in that range, which is too low for most test shakers, Monitran, locally represented by Instrotech , has developed a new high displacement test rig that can generate oscillations accurately at frequencies as low as 0,2 Hz. The system allows real-time back to back testing between different devices and its own inbuilt, calibrated MEMS sensors. The horizontal linear beam oscillator has a powerful motion control system that incorporates a precision ac servo with 17 bit encoder feedback. Running on two precision rails, it uses mag- netic springs and magnetic damping to ensure smooth operation. Its software produces fast code, at 1,7 milliradians per step, which generates fine sinusoidal motion for the linear track driven by a rotary motor. The intelligent shuttle, which can carry a sensor payload of up to 0,5 kg, incorporates seven MEMS accelerometers, signal processing and a microcontroller to monitor its motion. It also includes a mechanical low pass filter and has an operating distance of up to 1 000 mm, exerting

up to 8 g acceleration to the de- vices under test. That amounts over 35 kilometres per hour peak velocity, down to nearly 1/20th of walking speed. “The new oscillating beam rig gives us accurate extreme low frequency data and is a highly useful addition to our accelerom- eter test and calibration capabil- ities,” said Andy Anthony, Moni- tran’s managing director. Enquiries: Instrotech. Tel. +27 (0) 10 595 1831 or email sales@instrotech.co.za

Double troubleshooting power lighter load Fluke, locally represented by Comtest , now has the Fluke 787B and 789 ProcessMeter that doubles the troubleshooting capabilities by combining the power of a safety-rated, digital mul- timeter and mA loop calibrator into a single, compact test tool. Based on the trusted measurement capabilities of the Fluke 87 DMM, the new 787B and 789 add the ability to measure, source and simulate mA with the accuracy and resolution that can be expected from a Fluke mA loop calibrator, giving users the ideal tool for troubleshooting and calibrating current loop applications. The 787B and 789 key features: • 20 mA dc current source/measure/simulate • Simultaneous mA and % of scale readout • DMM designed to meet 1000 volt IEC 61010 CAT III and 600 V CAT IV standards • Precision 1 000 V, 440 mA true-rms digital multimeter • Frequency measurement to 20 kHz • Min/Max/Average/Hold/Relative modes • Diode test and continuity beeper • Manual step (100%, 25%, Coarse, Fine) plus Auto Step and Auto Ramp • Externally accessible battery for easy battery changes The 789 has the additional features of 24 V Loop power supply and HART mode setting with loop power (adds 250 ohm resistor). Enquiries:Tel. +27 (0) 10 595 1821 or email sales@comtest.co.za

Electricity + Control

SEPTEMBER 2017

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