Field of invention

The invention relates to a resettable safety device for suspended cables to disconnect and/or connect suspended electric or data cables having no support or service cable. The safety device disconnects a suspended cable and isolates it from electricity whenever the tension in the suspended cable reaches a threshold limit which may be due to an external object such as a tree or the like collapsing on the cable.

Background of the Invention

On electric poles with suspended cables having no support and/or service cables, there is a high risk of the cables snapping out due to increased tension caused by a tree collapsing on the cables. This results in the live wire falling on the ground, which is a potential threat to the lives of humans, and animals that accidentally come in contact with the live wire. A live wire may also cause other hazards such as an explosion due to the spark. The suspended cables mentioned here can refer to the cables between two electric poles and may also refer to the cables extending from a pole to a building.

When an external object, such as a tree, collapses on a suspended cable or if the electric pole collapses due to a natural calamity, the live wire gets snapped out of the suspended cables and falls on the ground. This is a potential for personal injury to a human or animal life or could even start a dangerous electric fire. The existing solution is to shut down the nearest power substation, which supplies electricity to this electric pole whose cable has snapped out.

US 4,698,717 discloses an electrical safety drop disconnect mechanism. However, the threshold tension in the suspended cables cannot be calibrated using this mechanism. In fact, the tension in the suspended cables has not been considered. Thus, if this approach is used to solve the stated problem, there is a high probability of failure. Moreover, the solution proposed in this prior patent is not suitable for high-tension electric cables, as the direction of electricity flow has to be considered while fitting this device. Any human error while deciding the direction of electricity flow while installing the device can be detrimental and the whole purpose addressing the problem is lost.

US 3,761,865 discloses a safety device for cables supporting electrical wires. This document discloses a breakaway connector for a suspension cable, which supports the electrical service, wires extending from power line pole to a building. It is not suitable for the cables suspended from one electrical pole to another.

Further, US 4,195,192 discloses a safety disconnect switch for suspended cables. This document discloses a device mounted on a utility pole to serve as an anchor at one end of a suspended service entrance cable extending to a remote building. Clearly, this does not address the technical problem of a snapping out of suspended cables between two electrical poles.

Object of the Invention

The solutions mentioned in the above-mentioned state of the art of disconnection of suspended cables are meant for service cables that are connected between the utility pole (electric pole) and the building. Clearly, these do not address the technical problem of a snapping out of suspended cables between the two electrical poles.

It is an object of the invention to provide a resettable safety device to disconnect and connect suspended cables having no support/service cable.

It is an object of the invention to provide a resettable safety device for adjusting to different tension ratings of the electric cables.

Further, it is an object of the invention to reconnect snapped cables for normal operation at a very less down time without having to disconnect the electricity supply to other consumers upstream.

Summary of the Invention

The invention relates to a resettable safety device including a mechanical fixture fixed on the electric pole. The suspended cable having no support/service cable is connected to this safety device. If the tension in this suspended cable increases beyond a certain limit due to external factors like a tree falling on the suspended cable, the safety device disconnects the cable mechanically, and thereby electrically. However, the cable still remains attached to the safety device. Thus, it causes no harm if the cable snaps out anywhere along the length, and falls on the ground while the other end is still attached to the safety device.

Also, if the cable does not snap out and the object such as a tree Is still hanging on the suspended cable causing sufficient increase in the tension, thereby reaching the minimum tension calibrated in the safety device, the safety device disconnects the cable mechanically, and thus prevents any harm to animal or human life that accidentally comes in contact with the hanging object. Also, the increase in the tension could be due to the adjacent pole falling due to natural calamity, in which case, the safety device ensures that the suspended cables get mechanically and thereby electrically disconnected. The reset feature of the device is used to put the device back in normal working condition. The threshold tension is configurable for different loads. The mechanism is enclosed to protect from environment.

Accordingly, the resettable safety device according to the instant invention is mountable on electric poles holding the power cables and in a normal scenario the cables are electrically connected through the device. The resettable safety device comprises a housing with contact rods passing through either sides of the housing at substantially the centre portion of the housing. The contact rods are capable of being detachable and re-attachable to each other at a contact point at the centre and at least a portion of the contact rods protrude outside the housing at opposite sides. The power cables are connected at the ends of each contact rod that protrude outside the housing. The resettable safety device can be imaginarily divided into a first side and a second side, wherein the first side has the same elements as the second side. The contact rod at the first side of the housing receives the cables coming in from the second side of the housing of a resettable safety device mounted on a previous electric pole. The second side of the housing transmits the cables to the first side of the housing of a resettable device mounted on the next electric pole. Each of the first and second side of the reset mechanism comprises a first tension plate and a second tension plate completely embracing the contact rod. The second tension plate is mounted between two ratchet mechanisms on opposite sides of the contact rod. A resilient member is connectively mounted above each ratchet mechanism and is inwardly and outwardly movable by operating the reset fastener, which is mounted on the wall of the housing. The resilient member and the reset fastener together form the reset mechanism of the device according to the present invention, which will be further elaborated below.

A second resilient member is fitted with tension between the first and the second tension plates. When a heavy object falls on the power cables suspended between two electric poles, the contact rods are pulled away and the second tension plate also moves together with the contact rod. This movement causes the contact rod to detach at its centre and causes the second resilient member to compress and remain in the compressed state until a user loosens the reset fastener to reset the device. The movement of the contact rod also causes the ratchet mechanism to expand outwards. The ratchet mechanism will assist in holding the second tension plate in still position thereby preventing the rods from reconnecting until a user loosens the reset fastener to reset the device. In this way the cables that get snapped due to the felling of the tree will be electrically I separated from the power before it breaks or hangs down and hence only a dead cable will lie on the ground. Therefore, if any living being comes into accidental contact with this cable, there will be no risk of hazard or accident. Upon loosening the reset fastener the ratchet moves and unlocks the second tension plate, which causes the second resilient member to expand and move the contact rods to re-attach and make contact at its centre.

The proposed solution with a reset mechanism has the advantage that the snapped cable can be reconnected for normal operation without having to electrically disconnect and thereby not affecting the electricity supply to other consumers upstream. Also, the time taken for resetting is considerably reduced when compared to other state of the art devices. The device is enclosed in a housing, which results in a foolproof device safe from unintended failures such as problems caused due to insects, severe weather conditions such as ice formation etc.

In another embodiment of the instant invention, the device is calibrated for a predetermined tension of the suspended cable above which the device disconnects the cable. Further, the threshold tension is configurable for different loads.

Accordingly, the invention relates to a resettable safety device for cables suspended between electric poles comprising: a housing, a first contact rod inserted through a first side of said housing and a second contact rod inserted through a second side of the housing, said first and second contact rods being detachably connected to each other at a central contact point, a part of said first and second contact rods protrudes from said first and second sides of the housing respectively to receive the cables suspended between said electric poles; each of said first and second contact rods being embraced by a stationary first tension plate and a spring loaded movable second tension plate, each of said spring loaded movable second tension plate capable of being independently moved in cooperation with respective contact rod in a direction of a pulling force experienced by said respective contact rod when a tension applied on said suspended cables exceeds a calibrated threshold tension; independently operable spring loaded mechanisms are provided within said housing to lock and prevent reverse movement of each of said second tension plates; and independently operable reset mechanisms engageably arranged with said spring loaded mechanisms to restore the position of each of said second tension plates and to reconnect said first contact rod and second contact rod at said contact point.

Brief Description of the Drawings

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same:

Figure 1 shows the normal scenario of the suspended cables used for power distribution,

Figure 2 shows a scenario where the suspended electric cables are snapped due to the collapse of a tree.

Figure 3 shows the resettable safety device of the instant invention mounted on the pole holding the power cables,

Figure 4 shows the resettable safety device of the instant invention in a scenario where the suspended electric cables are snapped due to collapse of a tree,

Figure 5a to 5c shows the front view, top view and side view respectively of the resettable device according to the instant invention.

Figure 6 shows the resettable device according to an embodiment of the invention,

Figure 7 shows the resettable device according to another embodiment of the invention.

Figure 8 shows the resettable device according to a further embodiment of the invention.

Figure 9a shows the resetting mechanism of the resettable device according to an embodiment of the invention.

Figure 9b shows a closer view of a resetting mechanism of the resettable device according to the present invention.

Figure 10 shows the resetting mechanism of the resettable device according to a further embodiment of the invention, and

Figure 11 shows the resetting mechanism of the resettable device according to a further embodiment of the invention.

Detailed Description of the Invention

Fig 1 to Fig 4 shows the example scenario in which the invention can be used.

Fig 1 shows the normal scenario of the suspended cables used for power distribution. The figure shows two electric poles (P) having electric cables (C) suspended between them. A tree (T) is found to be very near the electric poles, which has a risk of collapsing on the suspended cables In an extreme weather condition involving forceful wind.

Fig 2 shows a scenario where a tree has accidentally fallen on the live power- carrying cable. As a tree is a heavy object the cables are broken and lie on the ground. The broken cables are still live and carry power and this is a potential danger for any living being coming in contact with these live broken cables.

Fig 3 shows the resettable safety device (100) according to the instant invention in its normal state when mounted on the electric pole holding the power cables. In the normal state the cables are electrically and mechanically attached through the device.
Fig 4 shows the resettable device (100) in a problem state where a tree has accidentally fallen on the live power-carrying cable. As a result of the device according to the instant invention, the cables are electrically separated from the power before it breaks or hangs down and hence only a dead cable will lie on the ground, which is not a potential hazard for anyone who comes in contact with the cable.

The assembly and working of the resettable safety device in accordance with the instant invention will now be explained with reference to figures 5a -5c and 6 to 11.

As illustrated in figure 5a to 5c, the resettable safety device (100)(100) mountable on electric poles holding the power cables comprises a housing (8) closed on its sides by a cover plate (5) using removable fasteners (6). The housing is preferably substantially cylindrical to completely house the components of the resettable safety device (100). The device (100) can be visualized to have a first side (LS) and a second side (RS). The elements assembled in the first side (LS) of the device (100) can also be found in the second side (RS) of the device (100) and therefore the LS and RS are symmetrical. A first contact rod (3a) is inserted through the first side (LS) of the housing and a second contact rod (3b) is inserted through the second side (RS) of said housing. The first and second contact rods (3a, 3b) are inserted into the sides (LS, RS) of the housing (8) at substantially the centre portion of the housing (8). The first and second contact rods (3a, 3b) are capable of being detachably connectable to each other at a contact point (16) at the centre. Further, at least a part of the first and second contact rods (3a, 3b) protrude outside the first and second sides (LS, RS) of the housing (8) respectively. The power cables (1) are connected at the part of the first contact rod (3a) and the second contact rod (3b) that protrudes outside the first and second sides (LS, RS) of the housing (8). The first contact rod (3a) at the first side (LS) of the device (100) receives the cables (1) coming in from the second side of a resettable safety device (100) (not shown) mounted on a previous electric pole (not shown). The second contact rod (3b) on the second side (RS) of the device (100) transmits the cables to a first side of a resettable device (100) (not shown) mounted on the next electric pole (not shown).

The components assembled in the first side (LS) of the device (100) will now be explained in detail.

The power cable (1) is connected to the first contact rod (3a) through a first coupler (2a). A first stationary tension plate (7a) is provided to embrace the first contact rod (3a). The first stationary tension plate (7a) has a first tension adjustment collar (17a), which also acts as a guide for the first contact rod (3a). The first stationary tension plate (7a) is connected at its circumference to a first and second threaded tension adjuster (18a, 18b). The resettable safety device (100) can be calibrated for different load tension ratings using the first and second threaded tension adjusters (18a, 18b) and the first tension adjustment collar (17a). An operator can use an appropriate tool to rotate the first tension adjustment collar (17a) to set the desired tension threshold for the device (100). A tension scale (21) is printed on the first contact rod (3a), which indicates the threshold tension to which the device (100) is calibrated.

A first movable tension plate (15a) is provided to embrace the first contact rod (3a) at a distance away from the first stationary tension plate (7a). The first movable tension plate (15a) is placed between two independently operable spring-loaded linear or rotary unidirectional mechanisms (13a). Such a unidirectional mechanism can preferably be a ratchet or a similar toothed wheel. In its normal state the first movable tension plate (15a) is positioned at the end of the ratchet mechanisms (13a), which is closer to the contact point (16). A resilient member (12a) is placed above each of the ratchet mechanisms (13a) and is pressingly held at a certain force on the ratchet mechanism (13a) by respective reset fasteners (9). The reset fasteners (9) extend from a threaded portion (10) at the top and bottom walls of the housing (8) up to the resilient member (12a) as shown in figure 5a. As can be seen in figure 5a and 5c, the screw head of the fastener (9) protrudes outside the housing for easy access by an operator. In its fastened condition, the reset fasteners (9) on both top and bottom of the housing (8) press the respective resilient member (12a) with the respective ratchet mechanism (13a) at a certain force thereby holding the first movable tension plate (15a) in a first position between the two independently operable ratchet mechanisms (13a).

A first spring (14a) is fixed between the first stationary tension plate (7a) and the first movable tension plate (15a) in a free state. Thus, the first movable tension plate (15a) becomes a spring-loaded movable tension plate, which is capable of being pulled in the same direction as that of the first contact rod (3a).

The first contact rod (3a) and the first stationary tension plate (7a) are covered with insulating material (20) to prevent the device (100) from getting energized due to current. The insulating material (20) further eliminates electric shock while the device (100) is being manually handled. A grommet (4) is provided to surround the first tension adjustment collar (17a).
The components assembled in the second side (RS) of the device (100) will now be explained in detail.

The power cable (1) extending through the first contact rod (3a) passes through the second contact rod (3b) and further extends as a suspended cable through a second coupler (2b) to another resettable device (100) on the next adjacent electric pole. A second stationary tension plate (7b) is provided to embrace the second contact rod (3b). The second stationary tension plate (7b) has a second tension adjustment collar (17b), which also acts as a guide for the second contact rod (3b). The second stationary tension plate (7b) is connected at its circumference to a third and fourth threaded tension adjuster (18c, 18d). The resettable safety device (100) can be calibrated for different load tension ratings using the third and fourth threaded tension adjusters (18c, 18d) and the second tension adjustment collar (17b). An operator can use an appropriate tool to rotate the second tension adjustment collar (17b) to set the desired tension threshold for the device (100). A tension scale (21) is printed on the second contact rod (3b), which indicates the threshold tension to which the device (100) is calibrated.

A second movable tension plate (15b) is provided to embrace the second contact rod (3b) at a distance away from the second stationary tension plate (7b). The second movable tension plate (15b) is placed between two independently operable spring-loaded linear or rotary unidirectional mechanisms (13b). Such a unidirectional mechanism can preferably be a ratchet or a similar toothed wheel. In its normal state the second movable tension plate (15b) is positioned at the end of the ratchet mechanisms (13b), which is closer to the contact point (16). A resilient member (12b) is placed above each of the ratchet mechanisms (13b) and is pressingly held at a certain force on the ratchet mechanism (13b) by respective reset fasteners (9). The reset fasteners (9) extend from a threaded portion (10) at the top and bottom walls of the housing (8) up to the resilient member (12b) as shown in figure 5a. As can be seen in figure 5a and 5c, the screw head of the fastener (9) protrudes outside the housing for easy access by an operator. In its fastened condition, the reset fasteners (9) on both top and bottom of the housing (8) press the respective resilient member (12b) with the respective ratchet mechanism (13b) at a certain force thereby holding the second movable tension plate (15b) in a first position between the two independently operable ratchet mechanisms (13b).

A second spring (14b) is fixed between the second stationary tension plate (7b) and the second movable tension plate (15b) in a free state. Thus, the second movable tension plate (15b) becomes a spring-loaded movable tension plate, which is capable of being pulled in the same direction as that of the second contact rod (3b).

The second contact rod (3b) and the second stationary tension plate (7b) are covered with insulating material (20) to prevent the device (100) from getting energized due to current. The insulating material (20) further eliminates electric shock while the device (100) is being manually handled. A grommet (4) is provided to surround the second tension adjustment collar (17b).

It is to be understood that the functioning of the first side (LS) unit is independent of the functioning of the second side (RS) unit.

For maintenance purposes, the operator obtains access to the interior of the safety device (100) by removing the fasteners (6) using an appropriate tool.

Normal operative state

In the normal functioning of the resettable safety device (100) the cable (1) is connected to the first contact rod (3a) in the first side (LS) of the device (100). The first contact rod, through the contact point (16) in its centre, connects the cable (1) to the second contact rod (3b) in the second side (RS) of the device (100) and further to the adjacent electric pole (not shown). Thus complete connectivity of the cable (1) from one electric pole to the other is achieved through this device (100). As shown in figure 5a, the first and second couplers (2a, 2b) and a small part of the first and second contact rods (3a, 3b) extend outside the cover plate (5) on either side of the housing (8). The air/vacuum fills the space (19) within the housing as indicated in figure 5a and 5b. To set a desired threshold of tension for the device (100), the operator can use an appropriate tool to rotate the first tension adjustment collar (17a) and/or the second tension adjustment collar (17b). The normal operative state is said to exist for the device (100) if the minimum tension calibrated for the device (100) is not exceeded when a force is experienced by the suspended cable.

The first and second stationary tension plates (7a, 7b) and the first and second movable tension plate (15a, 15b) are provided to handle different loads of the cable (1). For example, to keep the first and second contact rods (3a, 3b) together in case of a high gauge cable, the tension plates (7a, 7b, 15a, 15b) need to induce enough compression in the springs (14a, 14b) to ensure that there is no loose contact at the contact point (16).

Different load (weight) of the cable can be due to either the gauge of the cable and/or the distance between the poles (length of the cable) and/or the material used for manufacturing the cable. The threshold tension of the cable should never be greater than the breakdown tension of the cable.

The tension adjust scale (21) indicates tension calibrated considering the threshold tension for separation as well as to keep the contacts intact to avoid loose connection.

In the first side (LS) of the device (100), the first stationary tension plate (7a) and the first tension adjustment collar (17a) are fused together. Similarly, in the second side (RS) of the device (100) the second stationary tension Plate (7b) and the second tension adjustment collar (17b) are fused together. Section A-A shown in figure 5c shows the cross section of the first side (LS) of the device (100), where the first tension adjustment collar (17a) is shown to have a square cross section and projects outside the housing (8). This projection helps in rotating the first stationary tension plate (7a) along the first and second threaded tension adjusters (18a, 18b) (towards or away from first movable tension plate (15a)) to adjust the tension of the first spring (14a), thereby, adjusting the force of the first contact rod (3a) at contact point (16).

Similarly, as can be visualized in a view (not shown but similar to figure 5c), when the cross section is viewed from the second side (RS) of the device (100), the first tension adjustment collar (17a) will also have a square cross section and would project outside the housing (8). This projection helps in rotating the second stationary tension plate (7b) along the third and fourth threaded tension adjusters (18c, 18d) (towards or away from second movable tension plate (15b)) to adjust the tension of the second spring (14b), thereby, adjusting the force of the second contact rod (3b) at contact point (16).

The first and second contact rods (3a, 3b) are not fused to each other but are rather held together with the help of the spring force of the first and second springs (14a, 14b). The connection at the contact point (16) between the first contact rod (3a) and the second contact rod (3b) is similar to a plug-and-socket type of arrangement.

Operation in an anomalous state
In a situation where an external factor triggers the collapse of a large and heavy object such as a tree, pole or the like on an electric cable suspended between two electric poles sufficient tension results on the cable to cause it to sag dangerously or to snap.

The resettable safety device (100) of the present invention, as illustrated in figure 6 ensures that the suspended cables get mechanically and thereby electrically disconnected, thereby leaving only a dead cable to sag or fall on the ground which does not carry any hazardous power.

Figure 6 shows a situation where a heavy object has collapsed on both the right and left side of an electric pole. As already mentioned the resettable safety device (100) according to the invention is connectable to cables on both sides of an electric pole. When a heavy object collapses on the power cables (1) suspended at both sides of an electric pole, the first contact rod (3a) and the second contact rod (3b) are pulled away from the housing resulting in the detachment of the first and second contact rods (3a, 3b) from the contact point (16). As mentioned earlier, the connection at the contact point (16) is similar to a plug-and-socket type of arrangement. The first contact rod (3a) and the second contact rod (3b) is guided through the first and second tension adjustment collars (17a, 17b) respectively. Since the first movable tension plate (15a) surrounds the first contact rod (3a), the first movable tension plate (15a) moves from its first normal position, in the direction of the first contact rod (3a), to a second position when the first contact rod (3a) is pulled due to a tension on the suspended cables that exceeds the calibrated threshold tension. Similarly, since the second movable tension plate (15b) surrounds the second contact rod (3b), the second movable tension plate (15b) moves from its first normal position, in the direction of the second contact rod (3b), to a second position when the second contact rod (3b) is pulled due to a tension on the suspended cables that exceeds the calibrated threshold tension. The detachment of the first and second contact rods (3a, 3b) from the contact point (16) results in the disconnection of the cable both mechanically and electrically.

In the first side (LS) of the device (100), when the first contact rod (3a) is pulled, the first movable tension plate (15a) is also pulled through the spring loaded mechanism (13a), preferably a ratchet mechanism, and gets positively locked between the teeth of the ratchet (13a) in the second position. This movement causes the ratchet (13a) to expand due to the resilient member (12a) present above the ratchet mechanism (13a) and to cause the first movable tension plate (15a) to be held in its second position thereby preventing the first contact rod (3a) from reconnecting until the device (100) is reset. Further, disconnection of the first contact rod (3a) causes the first spring (14a) to be fully compressed between the first stationary tension plate (7a) and the first movable tension plate (15a).

In the second side (RS) of the device (100), when the second contact rod (3b) is pulled, the second movable tension plate (15b) is also pulled through the spring loaded mechanism, preferably the ratchet mechanism (13b) and gets positively locked between the teeth of the ratchet (13b) in the second position. This movement causes the ratchet (13b) to expand due to the resilient member (12b) present above the ratchet mechanism (13b) and to cause the second movable tension plate (15b) to be held in its second position thereby preventing the second contact rod (3b) from reconnecting until the device (100) is reset. Further, disconnection of the second contact rod (3b) causes the second spring (14b) to be fully compressed between the second stationary tension plate (7b) and the second movable tension plate (15b).

Since figure 6 shows a situation where a heavy object has collapsed on both sides of an electric pole, it is seen that both the first side (LS) and the second side (RS) of the resettable safety device (100) has shifted from its original normal operative state position.
Figure 7 shows the front view and the top view of the resettable safety device (100) when there is a threshold tension occurrence due to a heavy object collapsing on the right side of an electric pole and hence the second side (RS) contact rod (3b) moves apart thereby disconnecting the cable electrically from the contact point (16).

Figure 8 shows the front view and the top view of the resettable safety device (100) when there is a threshold tension occurrence due to a heavy object collapsing on the left side of an electric pole and hence the first side (LS) contact rod (3a) moves apart thereby disconnecting the cable electrically from the contact point (16).

Resetting Mechanism

Figure 9a illustrates the resetting mechanism of the device (100) when the device (100) gets disconnected from both sides as shown in figure 6. To reset the device (100), the operator fully loosens all the reset fasteners (9) on both the first side (LS) and second side (RS) of the device (100) one by one. Once the reset fasteners (9) are loosened, the first and second movable tension plate (15) slips from the ratchet mechanisms (13a & 13b) since the force applied by the resilient member (12a & 12b) on the ratchet holding the first and second movable tension plates (15a & 15b) is removed. A lower wedge on notch (11) of the reset fastener (9) when operated, will move the respective ratchets (13a & 13b) outwards to unlock the first and second movable tension plates (15a & 15b) to facilitate the first and second springs (14a & 14b) to expand and to bring the first and second contact rods (3a & 3b) towards the contact point (16) thereby simultaneously bringing the first and second movable tension plates from the second position to the first position.

Figure 9b shows a closer view of the construction of one of said reset fastener (9) and its arrangement with the resilient member (12a) and ratchet mechanism (13a). In the normal operative state the upper wedge (11a) of the reset fastener (9) keeps the resilient member (12a) and the ratchet mechanism (13a) in its normal position by applying a downward force. During the reset operation the reset fastener (9) is unfastened along the threaded portion (10) on the housing (8) thus forcing an outward movement of the resilient member (12a) and the ratchet mechanism (13a) with the help of the lower wedge (lib). The reset fastener (9) and the resilient member (12a) are not fused and have a small clearance (11c) as shown in Section A.
Returning back to figure 9a, the first and second couplers (2a & 2b) act as a stopper for the respective first and second contact rods (3a & 3b) when they moves inward. If the operator rotates all the reset fasteners (9) the device (100) will come back to its normal position and first and second contact rods (3a & 3b) will become re-connected at the contact point (16). The fasteners (9) are then completely fastened to return the device (100) to its normal operative position.

Figure 10 shows a reset mechanism when the device (100) gets disconnected only from the right side as shown in figure 7. This may occur when a heavy object collapses only on the right side of the electric pole. If the operator fully loosens the fasteners (9) on the second side (RS), the resettable device (100) will come back in the normal operative position. The mechanism is similar to what was described with reference to figure 9a and 9b.

Figure 11 shows reset mechanism when the device (100) gets disconnected from left side as shown in fig 8. If the operator loosens up the left side reset screws (9), the device (100) will come back in the normal position. The mechanism is similar to what was described with reference to figure 9a and 9b.

Optionally, the resettable safety device (100) according to the instant invention may have a visible indicator when it is in a disconnected state so that an operator can identify the state of the device (100) from the ground without having to take the effort of climbing the pole to physically check the state of the device (100). For example, the first and second contact rods (3a, 3b) can be brightly colored and/or illuminated to indicate that the contact rod has moved from its normal position. This indication is to visually recognize the disconnection in the device (100) from a distance.

While the above paragraphs explain the various embodiments of the invention, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention.

WE CLAIM

1. A resettable safety device for cables suspended between electric poles comprising:
a housing;
a first contact rod inserted through a first side of said housing and a second contact rod inserted through a second side of the housing, said first and second contact rods being detachably connected to each other at a central contact point, a part of said first and second contact rods protrudes from said first and second sides of the housing respectively to receive the cables suspended between said electric poles;
each of said first and second contact rods being embraced by a stationary tension plate and a spring loaded movable tension plate, said spring loaded movable tension plates capable of being independently moved in cooperation with respective contact rods in a direction of a pulling force experienced by said respective contact rod when a tension applied on said suspended cables exceeds a calibrated threshold tension;
independently operable spring loaded mechanisms provided within said housing to lock and prevent reverse movement of each of said spring loaded movable tension plates; and
independently operable reset mechanisms engageably arranged with each of said spring loaded mechanisms to restore the position of each of said spring loaded movable tension plates and to reestablish connection between said first contact rod and second contact rod at said contact point.

2. The resettable safety device as claimed in claim 1, wherein said independently operable spring loaded mechanism includes a ratchet and a resilient member mounted above said ratchet, said spring loaded movable tension plates being placed firmly between at least two such independently operable spring loaded mechanisms positioned on opposite sides of respective contact rods.

3. The resettable safety device as claimed in claim 1 and 2, wherein said independently operable reset mechanism comprises a reset fastener having a notch with two wedge surfaces engageable with respective resilient member, wherein loosening of said reset fastener releases said spring loaded movable tension plate from said ratchets to facilitate said spring loaded movable tension plate and the contact rod to revert to a position where said first and second contact rods re-connect at said contact point, in which position said reset fastener is completely tightened.

4. The resettable safety device as claimed in any of the preceding claims, wherein said power cable is connected to said first or second contact rods through a coupler.

5. The resettable safety device as claimed in any of the preceding claims, wherein each of said first tension plate has a tension adjustment collar, which also acts as a guide for said first and second contact rods.

6. The resettable safety device as claimed in any of the preceding claims, wherein each of said stationary tension plate is connected at its circumference to a threaded tension adjuster.

7. The resettable safety device as claimed in any of the preceding claims, wherein said device is calibratable for different load tension ratings.

8. The resettable safety device as claimed in any of the preceding claims, wherein a tension scale is printed on said first and/or second contact rod, to indicate the calibrated threshold tension of the device.

9. The resettable safety device as claimed in claim 3,wherein said reset fasteners extend from a threaded portion provided at the top and bottom walls of said housing to respective first resilient members, and a screw head of said fastener protrudes outside said housing for access by an operator.

10. The resettable safety device as claimed in any of the preceding claims, wherein the first and second contact rods and the spring loaded movable tension plates are covered with an insulating material.

11. The resettable safety device as claimed in any of the preceding claims, wherein said device is mountable on an electric pole.

12. The resettable safety device as claimed in any of the preceding claims, wherein it comprises a visible indicator to determine the state of said device by an operator standing at ground level.

13. The resettable safety device as claimed in claim 12, wherein said first and second contact rods are brightly colored and/or illuminated to serve as said visible indicator.

14. The resettable safety device as claimed in any of the preceding claims, wherein said first and second contact rods and said first and second stationary tension plates are covered with an insulating material.