The inductor-based resistance meter is an instrument used by electricians to test proper insulation of cables conducting electrical current. Devices of this kind are used on construction sites, in residential and industrial buildings, with electrical power networks and telecommunication installations. The presented instrument measures the value of resistance thanks to the built-in crank inductor. It can operate independently of a power source, because the voltage required for making the measurement is generated by the user himself. In modern metres, analogue measurement of this type has been replaced by electronic systems, and the device is battery-powered. The presented device is manufactured by the German company Telegraphen-Bauanstalt von Siemens & Halske, which was founded by inventor Ernst Werner von Siemens and a precision mechanics expert, Johann Georg Halske in 1847. Initially, the company manufactured and refurbished telegraphs, over time its telecommunications and electrical engineering product range was expanded and new areas of production were entered. Finally, the company grew to be today’s International Corporation dealing with electrical engineering in the broadest sense.

References:
Siemens history, official Siemens website, https://new.siemens.com/global/en/company/about/history.html, accessed 2.06.2021.