ELECTRONIC MEASURING DEVICES FOR RATING AND MONITORING AMPACITY, AND FOR THE SAG OF POWER LINES; ELECTRONIC MONITORING DEVICES FOR POWER LINES; APPARATUS FOR RECORDING, TRANSMISSION OR REPRODUCTION OF SOUND OR IMAGES; BLANK MAGNETIC DATA CARRIERS; PRERECORDED MAGNETIC DATA CARRIERS CONTAINING INFORMATION IN THE FIELD ELECTRICITY, ELECTRICITY TRANSMISSION AND DISTRIBUTION; BLANK RECORDING DISCS; PRERECORDED RECORDING DISCS CONTAINING INFORMATION IN THE FIELD ELECTRICITY, ELECTRICITY TRANSMISSI...