In GIS substations

the intelligent secondary devices for protection are located either in the local control cabinet or near the GIS pipes.The devices for measuring and monitoring

such as electronic transformers

merging units

intelligent terminals

may fail during the operation of disconnector（DS）switching operations.The characteristics of the port disturbance voltage are indispensable for enacting the immunity requirements and protection measures.The onsite measurement is the unique approach to master the characteristics of the disturbance voltage

which may include: lots of high frequency components

ranging from several MHz to tens of MHz

even up to one hundred MHz;a short rise-time about nanoseconds;a duration time of a few hundreds of milliseconds.In this paper

by using the high speed digitizer as an alternative of the oscilloscope

optical fiber communication and the technical shielding box

a novel measurement system is developed.This system characterizes a smaller bulk

a lighter weight

a cheaper cost

a portable device and stronger anti-electromagnetic-interference.A series of tests

including DC high voltage

square wave

surge wave

and onsite measurement have been carried out to evaluate the performance of the system.These tests show that the system has specifications with max peak voltage 30 kV

risetime 5 ns.The system has been applied to measure in a 1 000 kV GIS substation.