System Description

The Energizer is the core of the electric fence system. It produces the High Voltage Impulses. The energizer also produces Low Voltage impulses at near ground voltage level, but isolated from the ground. These HV and LV impulses are fed to the naked fence wires installed through Insulators, mounted on fence pickets. HV and LV impulses are fed on alternating wires, to increase the chance of an intruder getting a shock / disturbing the system, resulting in generation of alarms.

The energizer is powered by a 12 V Dc battery, kept in the monitoring cabinet. The monitoring cabinet also features an interface circuit, which monitors the alarm data sent by the energizer. The interface unit, then sends the alarm data to the Central Monitoring System (CMS) or to a Local alarm Unit or to both, as required by the system configuration.

Alarm Conditions

Alarm will be generated in the following events:
1) Cutting of Fence wires
2) Shorting of HV or LV wires to ground
3) Cutting / disconnection in the data cable or disruption in the wireless communication link
4) Detection of shock ( Similar to shorting the HV wire to ground via a 1000 Ohms resistor)
5) Shorting of two line of HV OR LV Lines (This loop detection facility is offered only by Sivananda Electronics)
6) Opening of cabinet door (Separate alarm)

Loop Detection facility

All energizers used for security fencing offer detection of cutting of the fence wire. This is facilitated by monitoring the continuity of the HVOUT and HV-IN leads from and to the energizer. The connection from the energizer is as shown in the adjacent schematic. If a potential intruder cuts the fence wire at any point, the continuity is disrupted, resulting in an alarm condition.

But, an intelligent intruder, can make shorting loop across the parallel wires, as shown in the arrow in the second figure. If a suitable HV insulated wire is used, making such a loop is very easy. In fact such a shorting loop can be made across any section of the fence. As the energizer controller can see the continuity via the shorting loop, the lectrified portion beyond the short becomes redundant, making it easy for the intruder, to cut the wires, carefully, completely breaching the fence.

Sivananda uses special loop sensors, which are installed across any two parallel wires. They, in conjunction with the sensor circuit in the energizer, detects any attempt to make a shorting loop.

System Components 

A. Fence Energizer
The fence energizer offers two independent High Voltage zones and Two Low voltage zones. The specifications are given as below.
Output Voltage     : 2, 4, 6 & 8 KV, selectable
Output energy      : < 5 J / < 7 J, factory Set
Pulse Interval       : > 1 second 2.2 seconds, nominal
Pulse Duration     : 300 micro second, nominal
HV out put             : 2 Zones
LV out put             : 2 Zones
Input Power          : 12 V DC, < 1.5 A, nominal
Op. Temp. Range : - 20 Deg C to + 55 Deg C
Humidity                : 95 % Non Condensing
IS specification    : IS 302 2 76
IP Rating                : IP54

B. Energizer Monitor

Energizer monitor does the important function of interfacing the energizer to the alarm circuit. It is fixed inside the energizer monitor cabinet along with the battery and the battery charger. The monitor also offers two LV zones (As Option), which can be used for monitoring auxiliary zones, if required. The energizer monitor can be connected to the Local Alarm unit or the Central Monitoring system, via data cables or via RF links, as per site requirement. It also offers relay output for connecting to a siren, in case of alarm.
Features
HV zones monitored : 2
LV zones monitored : 2 (Standard)
Additional LV zones monitored : 2 (Option)
Alarm indication : LED
Battery Indication : LED
Coomunication Indication : LED
System ON / OFF : Switch
Zone ON / OFF : Switch

C. Energizer Monitoring cabinet

The cabinet houses the following.
i. Energizer Monitor
ii. Battery, 12 V DC, 28 AH
iii. Battery Charger, 1.5 A
iv. Complies with IP 55

D. Local Alarm Unit ( option)

The Local Alarm unit, can be supplied as an option. In many cases, especially in military sites, a local alarm unit is required to be installed at the sentry post near the perimeter wall. Even if there is a central monitoring system, the local alarm unit offers immediate alarm indication to the sentry in the post. The CMS will offer alarm data for all he energizers around the perimeter. The Local alarm unit offers alarm data with an audio buzz, for one energizer, to which it is connected.
Specifications
i. Input : 12 V Dc
 

Central Monitoring System (CMS)
The CMS is basically a PC based system. In normal configuration, a LAPTOP is offered to facilitate better battery back up. If required, a Desk Top PC can be offered in lieu of the Lap top PC. The CMS is installed at the main control room.

The CMS software is menu driven and allows the user to put the area map in the back ground. The location of various energizers and the extent of each zones can be programmed for display in the CMS screen. It continuously monitors the alarm data from all the energizers and provides an audio visual alarm on intrusion or fault conditions. The menu offers supervisory password protection to facilitate operational security.

RF Link
Line of sight RF links, operating at 2.4 Ghz are offered as standard. They have a range from 500 mtrs – 2.5 Kms depending on location and transmission power offered.

Data Link
The data from the energizer monitor is sent to the Local Alarm unit via data cable, normally. If equired this data can be sent via RF links also. To offer better reliability, especially in areas where RF jamming is in practice, cable link is preferable.

Similarly, the data connectivity to the CMS is also through cables or RF links, as required. A typical solution will be to provide cable connection the the Local Alarm units and Rf connection to the CMS or Vice Versa, so that at least one connection is always available.

Note :
Our Electric Fence system is installed in most difficult terrain under extreme weather conditions, covering nearly 300 Kms of perimeter. Service Support is provided even in the remotest locations including the Line Of Control in J&K.