A drone deployable power line fault detection sensor. The sensor can include a clamp mechanism having a clamp ring with first and second ring portions movably connected to each other and a resilient member positioned to urge the first and second ring portions toward a closed configuration. A latch can be positioned to retain the first and second ring portions in an open configuration whereby the sensor can be positioned on a power transmission line with a drone. A trigger can be coupled to the latch and operative, under the weight of the sensor, to disengage the latch thereby releasing the first and second ring portions to close around the transmission line under the force of the resilient member. One or more sensors are carried by the clamp mechanism and positioned to detect a line fault on the power transmission line, which is reported to a power station control system to de-energize the power transmission line.