P3 sensors
The purpose of the P3 sensor is to continuously monitor P3. In cases where there are multiple critical points, a P3 sensor will be installed on each of them. The pressure data is stored in the P3 sensor's 2Mb memory and sent via the GSM network once a day to the i2O server. This data is required for creating and continuously improving the algorithms and also for monitoring P3 against P3ref. If P3 falls below P3ref, an alarm is sent immediately to the server.
Key Features
Compact - The P3 sensor at 120mm by 220mm is extremely compact and designed to be installed in small valve chambers or boundary boxes.
Robust and water-proof - The environment in which the P3 sensors are installed can be very demanding with high levels of moisture, temperature variation, vibration and flooding. They may also be installed in chambers in the road which can fill with gravel or sand. Traffic driving over the chamber cover may then transmit considerable loads to the sensor. All P3 sensors are therefore installed in robust and watertight enclosures to IP68 and have been thoroughly tested in the harshest of environments.
High Accuracy - Unlike most conventional loggers which normally have a resolution of 0,5m, the P3 sensor has a resolution down to 0,05m. This enables more accurate measurement of P3 and improved pressure control
Large memory - At 2Mb, the unit has a much larger memory than most conventional loggers. This is particularly important if GSM communication is not reliable due to weak signal strength. It also enables fast logging of P3 pressure to take place.
Fast logging - The interval over which the unit measures P3 can be adjusted remotely from 0.1 sec upwards. In normal operation, the system generates 1min data but regular periods of faster logging can be programmed in order to detect any pressure transients or spikes in the system.
Advanced power management - Remaining battery life is one of the parameters that is calculated and regularly reported. This gives enough warning to replace batteries during planned maintenance or inspection visits. An alarm is also sent back to the server once a battery change is needed urgently. Should the main battery fail or become empty, the unit switches automatically to its back-up battery. P3 continues to be measured and stored in the unit’s 2Mb memory but there is no further transmission until the main battery is replaced.
Low power consumption - A number of design strategies have been employed to achieve exceptionally low power consumption. The length of time between battery changes depends on the number of data transmissions per day. Under normal circumstances there would be one transmission per day which would give a battery life in excess of five years.
HTTP protocol - All transmissions to and from the P3 sensors are made using the standard HTTP protocol. For setting up or manually retrieving data, it may sometimes be necessary to connect a PC or PDA to the sensor via USB, Bluetooth or GPRS. The benefit of using HTTP is that the PC or PDA can view or send data using a standard internet browser such as Internet Explorer. Data files can also be transferred easily to and from the sensor using Microsoft Explorer.
GPRS - Where there is an adequate GSM signal, the P3 sensor will use GPRS to communicate with the central server. This enables it to transmit and receive enough data each day to update the main algorithms and for reporting purposes. The GPRS transmission is initiated by the sensor or controller once each day.
SMS - Where signal strength is limited, the P3 sensor may use SMS to communicate with the central server as an alternative to GPRS.
Bluetooth - It may sometimes be necessary, during set up or if GSM is not available, to connect a PC or PDA directly to the P3 sensor. Bluetooth makes this very convenient as the sensor or controller does not need to be disturbed or uninstalled nor do any covers need to be removed to access physical connectors.
USB - A USB interface is also provided as back-up to the Bluetooth and for use during servicing of the unit.
Antenna technology - The latest antenna technology is used which in most cases will enable the antenna to be mounted within a valve chamber. However, in areas with low signal strength, a remote antenna can be used. This can be installed in a variety of different ways depending on the environment. Common solutions are to mount the antenna on a lamp-post or in a bollard at the side of the road.
Alarms - If pressure goes outside acceptable limits, an alarm is sent in real time direct to a specified mobile phone or email address as well as the central server.