This thesis describes the development of the device which observes transients on surge protection devices. The device, which is named ProSECIII (Surge Event Counter), measures current amplitude and stores it in a memory with time and date stamp. It also has many features like LCD for history reading, wireless communication, remote contacts etc. The thesis describes research and development of analogue part of a circuit, which is based on Rogowski principle for current measurement. After design and implementation phase, the tests procedures follow. There is also a chapter about shielding the device to be immune to electromagnetic interference.
The main feature of this device is providing information about transients which passes SPDs and SPD status.