This paper presents problems related to transient detection and monitoring in electric power systems. It consists of two parts. Firstly, a problem of frequency characteristic of real impulses is considered. Parameters of the selected transient and notching disturbances are determined after extracting disturbances by pass-band filters with various cut-off frequencies. Further, results of wavelet transform application for estimation of selected disturbances are presented. Secondly, basic features of the prototype of original multi-parameter instrumentation for power quality assessment are shown and its transient monitoring capabilities are described on the basis of laboratory research of the testing signals. This new measurement instrument utilizes the digital signal processor (DSP) technique.