An electrician wrote on the Electricians & Electrical Forum, UK:
“URGENT HELP NEEDED!!
I have a client here in France who has a house in a remote location. The house has been broken into three times this year and I have been asked to install a GSM alarm with no outside or internal sounder, due to the fact that the last alarm system was just smashed off the wall. What I actually need is a lithium powered wireless alarm with a telephone dialler as the house it is to protect is remote and left unoccupied for long periods of time. The other problem is that the house does not have mains electricity, but a rather complex generator/battery set up which has been known not to auto-start.”
Indeed, where no mains power is available, classical alarm systems are not applicable. This is commonly the case in off grid military depots, private boats, holiday homes, builder sheds, farm sheds, aircraft hangars, etc.
There are also cases where mains powered alarm systems fail to operate after a power blackout, due to a backup battery failure or a disturbance caused by the outage.
Infinite’s autonomous RTUs, combined with new technology, ultra low power PIR sensors, offer highly reliable solutions in security. An SMS alarming system, consisting of a BSC-50D RTU and a low power PIR sensor for motion detection, can operate for over 10 years, powered only by one Lithium D-size battery!
Proposal
AERINOSTM BSC-50D battery powered RTU with an OPTEX EX-35R sensor is an optimal solution for long term, autonomous intrusion alarming. The EX-35R is an ultra low power PIR sensor, drawing only 3.5μA in standby operation. The PIR sensor is powered from the BSC-50D internal battery. A ‘Walk test’ option with LED indication can be selected, by a sensor internal jumper, for adjusting the detection range.
The sensor provides two Form C solid state switches (NO, NC, COM), one for motion alarm and one for tamper alarm. The sensor outputs are wired to the DI1 and DI2 BSC-50D digital inputs. The NO terminal is used for the Alarm input (DI1). For the Tamper input (DI2), the NC terminal is used, in order to include the case of cutting the cable. An ON-OFF switch, wired to BSC-50D DI3, is used to disable (On position) the GSM alarming (Disarm switch).
Up to 20 SMS recipients can be declared in the BSC-50D unit. The unit sends a Status SMS to the administrator on transitions between arm and disarm state. The unit can also send periodical status messages to the administrator, for verifying the system availability and GSM signal strength. A wireless RF Remote Control Switch, as the Velleman VM130 remote control set, can be applied in the place of a hand switch, for arming and disarming the alarm system remotely.
An additional digital input (DI4) is available for connecting door or window switches to the BSC-50D unit with a respective alarm annunciation.
The BSC-50D internal temperature sensor can be used to measure and record temperature with periodical data transfer. The unit can remain connected on the GSM network for a short period (up to 255 seconds) after sending a Status SMS, expecting a remote configuration SMS from the system administrator, e.g. add or remove a user, change timings and rates, etc.
Features
- SMS Alarming
- Autonomous operation for over 10 years
- Arm/Disarm capability
- Flexible user administration
- Periodically sending status messages
- Simple setup and installation
- Remote configuration capability
Battery lifetime
Different low power sensors can be used for indoor and outdoor applications. The lifetime of the BSC-50D internal battery (LSH-20) depends on the current draw of the applied sensor. In some cases extra batteries for the sensors must be provided for the proper system operation. In the following table, the battery lifetime is calculated for different low power OPTEX motion sensors:
| Sensor | Application | Sensor batteries | BSC-50E Battery lifetime [Years] | System operation [Years] |
|---|---|---|---|---|
| EX-35R | Indoor | – | >10 | >10 |
| CX-0702RS | Indoor | – | >10 | >10 |
| FTN-R/RAM | Outdoor | – | >10 | >10 |
| BX-80NR | Outdoor | – | >10 | >10 |
| VX-402R | Outdoor | – | >10 | >10 |
| AX-100/200TFR | Perimeter | 2+2 1) | >10 | >3 2) |
| SL-350QFR/QNR | Perimeter | 4+4 1) | >10 | >8 2) |
1) SAFT LSH-20 batteries are recommended from the sensor manufacturer for transmitter & receiver.
2) The transmitter’s batteries lifetime determines the maintenance free operation of the system.
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