The present invention relates to a system for spiking, i.e. exploring voltage in electric cables.

When preparing for cutting or connection operations of electric cables, e.g. medium voltage cables, it is essential to explore the presence or absence of electric voltage in the cable.

The voltage exploration operation is usually performed by means of an exploring apparatus called “spike tool”, which clamps a portion of externally isolated electric cable in a position which prevents a displacement of the single conductors of the cable, e.g. of the three individual conductors of a triplex, and which pushes a metal blade through the external insulation of the locked cable so as to put the individual conductors into electric contact with one another. If there is no voltage in the electric cable, the penetration of the metal blade into the cable has no effects except locally damaging the cable. If there is voltage in the electric cable, the penetration of the metal blade into the cable creates a short circuit and the formation of an electric arc which can be detected as an explosion.

A known voltage exploring apparatus comprises:two clamping jaws, shaped to receive a portion of an electric cable to be explored between each other,tightening means associated with the clamping jaws and adapted to allow an opening of the clamping jaws to receive the electric cable portion between each other and to tighten the clamping jaws against each other to clamp the electric cable portion in a clamping position,a metal blade connected to one of the jaws in displaceable manner between a retracted position, in which the blade does not interfere with the clamping position of the portion of electric cable, and an extended position, in which the blade extends through the clamping position of the portion of electric cable, so as to put individual conductors of the electric cable into electrical contact with one another,an explosive capsule associated with the metal blade, the explosion of which moves the blade from the retracted position into the extended position,a remote ignition device, connected by means of an ignition wire to the explosive capsule which can be actuated to explode the explosive capsule.

The known voltage exploring apparatuses allows, by virtue of the instantaneous effect of the explosion, an almost instantaneous (non-progressive) electric contact of the conductors of the explored electric cable. However, the need to store, transport and handle the explosive capsules is regarded as problematic and requires skilled and certified labor.

The exploration noise similar to a firearm shot and the explosion fumes are considered very annoying. Furthermore, after a limited number of explorations by detonation actuating, the exploring apparatus must be subjected to maintenance because of the destructive effect of the explosion on the blade and on the other components of the apparatus. Finally, the material connection of the operator with the electric cable during the voltage exploration, because of the ignition wire and the explosion of the explosive capsule itself are subjectively perceived as dangerous.

If the exploration operation shows no effect (presumably due to lack of electric voltage in the conductors) it is still necessary to check that the metal blade has truly penetrated in a complete manner through the electric cable. With the apparatus of the prior art, this verification requires a visual inspection of the position of the blade after the explosion of the explosive capsule and, hence, an approach of the operator to the cable damaged by the blade but without the absolute certainty that the exploration has been performed correctly and completely.

It is thus the object of the present invention to provide a system for spiking, i.e. exploring voltage in electric cables, having such features as to overcome at least some of the drawbacks mentioned with reference to the prior art.

These and other objects are achieved by means of a voltage exploring system according to claim1. The dependent claims relate to advantageous embodiments.

According to an aspect of the invention, a system for spiking, i.e. exploring voltage in electric cables, comprises:

A) an exploring apparatus having:

a first clamping jaw and a second clamping jaw, shaped to receive between each other a portion of an electric cable to be explored,a reversible tightening device associated with the clamping jaws and adapted to allow an opening of the clamping jaws to receive the electric cable portion between each other and to tighten the clamping jaws against each other to clamp the electric cable portion in a clamping position,an elongated metal blade connected to the first clamping jaw and which can be displaced between a retracted position, in which the blade does not interfere with the clamping position, and an extended position, in which the blade extends through the clamping position, so as to penetrate the electric cable portion and to put individual conductors of the electric cable into electric contact with one another,a hydraulic actuator connected to the first clamping jaw and configured to displace the blade, with respect to the first and second clamping jaws, from the retracted position into the extended position, in response to a pressure increase of a hydraulic liquid,a pump adapted to increase a pressure of a hydraulic liquid,a flexible pressure hose connected between the pump and the hydraulic actuator so as to communicate the hydraulic fluid pressure from the pump to the hydraulic actuator, the voltage exploring system further comprising:
B) a hand-held remote controller for remotely actuating and controlling the pump,
C) actuation communication means adapted to provide pump actuation signals from the remote controller to the pump,

wherein:the hand-held remote controller is physically separate from the exploring apparatus and from any accessories physically connected thereto, so as to allow a positioning of the remote controller at a safe distance from the exploring apparatus,the actuation communication means comprise a wireless connection which exceeds said safety distance.

The provided exploring system avoids the need to hold, carry and handle explosive detonators, and the related risks, reduces acoustic and air pollution in the voltage exploration site and physically separates (electric isolation barrier) the exploring apparatus from the operator, thereby protecting the operator from any risk of electrocution and also overcoming the even only subjective perception of operating in condition of risk. Finally, the wireless transmission of commands for actuating the exploring apparatus allows the operator to be effectively sheltered from the exploration zone.

According to an advantageous aspect of the invention, the exploring apparatus further comprises:a blade position detector connected to the first clamping jaw and configured to detect the arrival of the blade in the extended position and to provide a signal confirming the reaching of the extended position of the blade,exploring confirmation communication means connected to the position detector and adapted to transmit an exploring confirmation signal in dependency of the reaching of the extended position of the blade,
wherein the exploring confirmation communication means comprise a wireless transmitter and/or contactless signaling means.

This allows the operator to obtain information on the completion of the voltage exploration, even before approaching the pump or the explored electric cable, in order to be able to proceed safely with the subsequent operations of extraction of the blade from the electric cable etc., as well as to be able to promptly interrupt the pressurization of the hydraulic liquid and in this manner reduce the consumption of energy (battery) and extend the life of the mechanically stressed components.

