(1) These observations were supported by the use of sound level and oscillograph records.

(2) Pressure and length gauge traces, electrocardiograms, and epicardial electrograms, at a frequency response of 30 to 250 Hz, were displayed and recorded on a multichannel oscillograph at paper speeds of 100 to 150 mm/s.

(3) The oscillographic data were also fed to computers and stored using data acquisition software (Biopac, US).

(4) The protection elements in the relay are complementary to those found in existing designs with major enhancements afforded by digital technology such as oscillography and sequence of events reporting.