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RoadTests & Reviews

11 Posts authored by: three-phase
Introduction What is a Data Acquisition System? Market Review Cost of Ownership Module Types Build Quality Power Consumption Tests Performance Tests Operation with the BenchVue software. Summary Introduction  This is my opening blog on the DAQ970A data acquisition unit that I was lucky enough to be selected to road test. This is a general blog, with my intention to introduce the DAQ970A.   I didn't really do an unboxing as they don't do an awfu ...
During my review of the Megger  MIT420/2 insulation tester in Blog 9, I tested a 120MW Generator rotor winding that actually failed the insulation resistance test. Following this issue, the bedplate heaters for the generator were reconnected and placed back into service. Around 4 weeks later, I returned to the generator to carry out a further insulation test with the expectation that the heat would have driven out the moisture from the winding and a healthy insulation reading would be obtai ...
You will all be thankful to know that I have finally reached my last blog in this road test review of the Megger  MIT420/2 Previous blogs have covered bench reviews and tests a teardown and insulation testing from electrical panels on motors and air circuit breakers In this blog I will cover the testing of generator rotor windings from a 92MVA and a 145MVA turbogenerator.     This is the main function of my job and the reason why the road test was of great interest to me. I cur ...
Up to this point the on site tests carried out with the  MIT420/2 have been based around motor tests either from a control centre or direct at the motor terminals Unsurprisingly the instrument has performed very well with the only issues really being around making connections to specific items during the earth test on a large motor and when using the supplied test lead to short out the winding after the tests These are all minor issues and relatives easy to overcome   This blog introd ...
In the previous blog some motors that had been refitted after maintenance were tested from their respective control panels I found that the  MIT420/2 had a few quirks whilst using it but nothing that became a major issue or prevented the instrument from being used In the next blog I am off to the other end of the cable and test out some motors at the actual terminal box Actually I am cheating a bit as I have access to motor stores so I tested a new 4kW motor a refurbished 90kW motor and two ...
The bench tests and desktop review have all gone well for the MIT420/2 Insulation Tester. In the next blog, I carried out some phase balance and insulation resistance tests from a low voltage (400V) motor control centre (MCC) for a gas turbine. The motor control centre is a large panel with two main feeders and then split down into multiple direct-on-line starters for various pumps and fans that the gas turbine requires to operate. The motors had been removed for maintenance work and then refitt ...
The last two blogs covered the bench tests applied to the  MIT420/2 and found that it performed better than expectations with all values obtained significantly within the manufacturer's specified tolerances However working on high energy electrical circuits has many safety implications so before I take the  MIT420/2 out into the field to do some real work I wanted to take a quick look at some of those safety features   As standard with most electrical instruments these days the ...
Part A of the Bench Tests reviewed the performance of the auxiliary functions on the insulation tester and found them all to be well within the specified tolerances. In this second part of the Bench Tests, I will concentrate exclusively on the insulation testing function.   The MIT420/2 has five fixed voltages of 50V, 100V, 250V, 500V and 1000V and then a variable output function from 10V up to 1000V. This is not a voltage ramp function, the output voltage is set in the settings menu to th ...
In Blog 2 I opened up the  MIT420/2 insulation tester and found a well designed instrument with good quality construction and design methods to improve the robustness and safety of the instruments In this blog I will carry out some bench tests on the instrument to ascertain its functionality and accuracy This blog will concentrate on the auxiliary continuity resistance capacitance and voltage functions Any of the manufacturer's tolerance I have quoted in this blog can be found from their da ...
In the last blog I took an overview approach to the  MIT420/2 Insulation Tester package that I have been sent to review In this blog I plan to concentrate on the instrument itself to review its build quality and design features   To gain access inside the meter, the battery and fuse compartment lids are removed. As these are subject to more wear and tear, Megger have used steel screws captivated within each compartment lid that screw into brass inserts in the meter body which should ...
I have been selected to road test the Megger MIT420/2 for the element14 community and this first blog is an introduction to the various elements of the package that has arrived and what I intend to do for the review.   The first item, often overlooked, is the case. For an engineer, such as myself, that travels from site to site, protection of the instrument during transit is extremely important. The meter sells for around £500 in the UK, not including VAT, so damage would be an expe ...

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