One particular feature of the new range is feedback-stabilised test voltage, which means the test voltage you select is the voltage the instrument uses. You may have assumed that this was always the case and if so, you might be surprised to know that the IET Wiring Regulations actually allow a variation of up to 20% on nominal insulation test voltages.
That means when you set an ordinary insulation tester to 500 V, you could actually be testing at just 400 V or, possibly even worse, at as much as 600 V! Stabilised test voltage is convenient as you know for sure, without having to check, that the test voltage will always be within 2% of the value you’ve selected.
While we’re talking about test voltages, it’s fair to say that most insulation tests are carried out at standard voltages – 250 V, 500 V or 1,000 V for example. But there are cases, particularly with electronic items, where the manufacturer specifies some other voltage. With the new Megger MIT400 Mk 2 testers, this isn’t a problem, because many models allow the test voltage to be adjusted in 1 V steps over a very wide range.
And then there’s battery life. Insulation test sets can be notorious battery gobblers, and the batteries always seem to run out at the most inconvenient time. This means that the extended battery life offered by the new testers – a minimum of 3,000 tests from a set of six ordinary AA batteries – is a very useful feature.
Some Megger MIT400 Mk 2 series testers go even further by accommodating rechargeable cells that can be recharged without removing them from the instrument. These are a very convenient source of power and, over the life of the tester they will save a lot of money.
It’s a fair bet that most users will actually carry out more continuity tests than insulation tests! For this reason, a continuity test function with a fast reaction time is very important. Even a delay of 100 milliseconds or so soon becomes annoying if you’re carrying out a lot of continuity checks.
Megger’s new instruments not only offer fast-reaction continuity checking, they also offer a choice of continuity test currents – 200 mA and 20 mA. They’re not the only testers that do this, but for most others the maximum circuit resistance for a 200 mA test is just 10 Ω. With the latest Megger instruments, this limit is extended to a much more useful 20 Ω.
Naturally, the new instruments incorporate all of the features traditionally associated with Megger products, including robust construction, reliability, convenience, ease of use and outstanding value for money. With all of this in mind, it may well be time to think again about your existing insulation tester. Is it past its prime? Are its limitations starting to show? And would your life be easier with a newer model? If your answer to any of these questions is yes, an instrument from Megger’s MIT400 Mk2 range is the right choice for you!
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