Alarm system for detecting hazards due to power transmission lines

Abstract

An alarm system for detecting and warning of the risk of shock and electrocution is provided. The alarm system is adapted for use with mobile construction equipment, e.g., cranes, trucks, etc., that can be used around overhead power transmission lines. The present alarm system has a sensor that detects the presence of outside power at the equipment where current is flowing therethrough to ground. The sensor preferably includes a conductor and an inductive sensor such as a current transformer which limits the output signal on its low side that is sent to an alarm unit. In this manner, the system herein continues to properly function despite the presence of large voltages at the equipment such as when the equipment contacts a high voltage power transmission line. The sensor can include a cable that provides a path of least resistance for current flowing through the equipment which can be detected by the sensor. Preferably, the cable is attached across a moving joint of the equipment where potential differences readily can be found. Alternatively, the conductor can be a portion of the equipment itself through which current flows with the sensor detecting the flow through the equipment portion.