MEGGER resistance tester ordered from Germany*

MEGGER resistance tester ordered from Germany*
Megger Limited was founded in 1889 and is a professional manufacturer of power testing equipment and power system measuring instruments.
The company was initially known for its insulation testers, but now it also provides testing instruments in the following fields: transformer testing, circuit breaker testing, relay protection testing, cable fault location, grounding testing, low resistance testing, power quality, wire systems, multimeters, clamp meters, etc.
The company's logo is the letter Megger, with the red capital letter 'M', the remaining letters in black, and a white background.

MEGGER resistance tester ordered from Germany*
MEGGER resistance tester is a tool for electrical safety inspection and completion acceptance of grounding engineering. Including grounding resistance tester, insulation resistance tester, DC resistance tester, surface resistance tester, and loop resistance tester. The circuit resistance tester (transformer circuit resistance tester) is suitable for testing the contact resistance value of the main contacts of high and low voltage switches, as well as the DC resistance value of high and low voltage cable lines. The intelligent circuit resistance tester adopts 100A constant current output. The maximum output voltage of 10V (2-3 times that of conventional instruments) can be achieved through the use of thin test lines, greatly reducing the labor intensity of on-site testing personnel. The testing process is entirely controlled by a single chip and automatically implemented, with high accuracy, good repeatability, single button operation, simple and easy to implement, and LCD display of test data. Suitable for different work environments. The grounding resistance tester is a commonly used instrument for testing and measuring grounding resistance. In recent years, due to the rapid development of computer technology, the grounding resistance tester has also incorporated a large amount of microprocessor technology. Its measurement function, content, and accuracy cannot be compared to general instruments.
MEGGER DC resistance tester is a new generation of transformer DC resistance testing instrument. It can automatically select the test current according to different models of power transformers and display the test results at the fastest speed possible. The DC resistance tester has functions such as storage, printing, and discharge indication. It is equipped with a built-in power-off memory that can save measurement data. The use of a LCD display makes the instrument have a good human-machine interface and is an essential device for DC resistance testing

Working principle of MEGGER resistance tester
A megohmmeter measures resistance by exciting the device or network under test with a voltage, and then measuring the current generated by the excitation using Ohm's law. An excellent megohmmeter calibrator includes various optional resistors, which are not significantly different from the resistors provided by modern calibrators using synthetic resistor functionality. The difference between a megohmmeter calibrator and a DC/low-frequency calibrator lies in the required range of resistors and the ability to withstand different voltages. For example, compared to the ohmmeter function equipped on a digital multimeter (DMM), these electrical testers apply much higher voltage when measuring resistance. The voltage range used by a megohmmeter is usually from 50V
Synthetic resistor
The method of synthesizing resistors is excluded due to limitations in design cost and size specifications. The method used is a matrix of discrete high-voltage resistors, forming an array that can provide over 500000 resistance values for output. In this calibrator, there are 8 ranges of resistance values covering the range of 10 k Ω to 10 G Ω, and each range can provide a stable output of 4.5 bits.
Collecting suitable high-voltage resistors and integrating them into one instrument presents another challenge. This is a safety standard challenge related to the mandatory requirement of the Low Voltage Directive for EU CE certification. The standard related to instrument manufacturers is EN 61010- Safety Requirements for Electrical Equipment for Measurement, Control and Laboratory Use.
The low voltage command requires limiting the calibrator voltage to 1000 Vrms. So how to calibrate and test a megohmmeter with a voltage of up to 5 kV? This type of instrument has a wider dynamic range, can measure resistance up to 10 T Ω, and provides protective terminals as described above, allowing it to accurately measure very high resistance values. Fortunately, this protection configuration can form a resistance multiplier itself, effectively doubling a known resistance to 1000 times, as shown in the example in Figure 2 [3]. Equally important, as the multiplier is a separate, isolated, and independent device that can meet the high voltage requirements of the multiplier, it is no longer within the scope of the Low Voltage Directive.

MIT400, MIT410, MIT220, BM12, MIT230, MIT1020/2, BM227, SP1, 1000-761, MIT481
DLRO-10X, MIT310A, DET4TC2, MFT1815, PAT450-DE, MIT230, MTK320, MFT1720
1000-767、、1001-088、PAT350-BS、1000-748、1000-751、1000-752 、1000-770、1001-081
1001-064 1000-745, 1000-755, 1001-093, 1000-633, 1001-063, 1000-762, 1000-971