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Insulation Tester


This is a photograph of a 20 Tera Ohm Insulation Tester I made around 20 Years Back. It had even Polarization Index for Transformer Insulation.

Insulation Resistance Testing - AEMC

A regulated, low ripple, high voltage of very low current capability is applied by instrument on a DUT  (device under test). The leakage current in nA or pA (picoamps, nanoamps) is measured and readout, The Innovation i did was to measure the current in Vref and not Vin of ICL7107, this made the 1/x computation.

Also using the ICL7650 Chopper Stabilized amplifier must be done as shown in data sheets with grounded guard rings. pA will leak on the PCB itself if layout is not done keeping this in mind. 

Insulation Tester



Megohmmeter or Megger is a special type of ohmmeter used to measure the electrical resistance of insulators. Insulating components, for example cable jackets, must be tested for their insulation strength at the time of commissioning and as part of maintenance of high voltage electrical equipment and installations.

Multi-Instrument Digital Assistant

Megger BM0413 by Thorn EMI Instruments

Megger BM0413. The simple battery-powered models with analog display. It is still popular among electricians. You can Notice this can go upto 200 Mega Ohms. It can also measure wire/cable resistance in the lower ranges. This is an Analog Electronic Meter.

Megger BM0413 by Thorn EMI
                                      Instruments

Dana Tekno Crossmeg Insulation Tester

Dana-Tekno Crossmeg. Antik Danish manufactured insulation tester with cross-coil instrument . Viewer's position is random until crank (dynamo) turn. This is an Electromechanical Device with no Electronics.

Dana Tekno Crossmeg
                                      Insulation Tester

A Electromechanical Dynamo Generator produces a AC Sine Supply when Cranked and this is fed to a Step-Up Transformer of very low Power and Special Insulation. Generates 100V to 1000 V or More.

The Voltage is then Applied on the DUT - Device Under Test. The Leakage of current is measured by a Sensitive Moving Coil Ammeter.

LC Meter PIC 16F84 - Phil Rice VK3BHR

Later developments have used SMPS and Batteries for HV. The Leakage currents are then Measured by Opamp Circuits that drives Meters both Analog or Digital.



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