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39
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
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