Refrigerated container monitoring
At around 5,000 worldwide container ships with around 2 million TEU - reefers pitches.ids there are different systems of refrigerated container monitoring for preservation of functionality. Loaded refrigerated containers are monitored on the ships and at container terminals in the port by the four-wire monitoring system or carrier frequency systems known as power cable transmission.
Refrigerated container monitoring
Refrigerated containers require personnel on the ships and at the container terminal in the port to control the refrigerated container units and the temperatures of the refrigerated cargo. In order to check and document the condition of the individual refrigerated containers, several inspections are carried out every day.
Four-wire monitoring
Remote monitoring of refrigerated containers, known as so-called four-wire monitoring, was developed at an early stage to save personnel. For at is Container an outlet connected to the controller installed in the additional signal wire is connected to the cooling container. The signal cable leads into the ship's office or the engine control room of the ship and shows whether the refrigeration compressor is working or whether the evaporator is being defrosted. It is also reported whether the temperature is within the permissible range. Originally, more than 75% of all refrigerated containers were equipped with it, with a downward trend.
Power Cable Transmission
A technically more sophisticated solution was implemented with the carrier frequency systems , which additionally modulate the information to be transmitted via one or more carrier frequencies onto the power supply line that is always present. It is known as powerline communication. In shipping it is commonly referred to as Power Cable Transmission (PCT).
The advantage of this method is that there is no additional signal line, which also reduces the work involved in connecting the refrigerated containers on board and in the container terminals. A significant advance is that this method allows information to be transmitted in both directions. This means that the setting values such as the temperature setpoint can also be changed remotely by authorized persons. It is even more interesting that the pre-trip inspection (PTI) of the empty refrigerated container on board or in the port can be carried out remotely, which saves costs.
These advantages mean that the previous method of four-wire monitoring is largely superseded. The PCT method requires a modem as additional equipment in every refrigerated container. Several master modems are also installed on the container ship or terminal; the number depends on the number of refrigerated container spaces. The data from the master modems are transmitted via a bus system to the master computer in the ship or terminal, which saves and displays the data and, if necessary, triggers alarms.
See also
Individual evidence
- H. Dakir: For data transmission when monitoring refrigerated containers via the ship's on- board network . Dissertation TUHH M4. Publishing house Dr. Hut, Munich 2011, ISBN 978-3-8439-0210-6 .