To detect thefts the processed data is used (it is done on the Data preparation and Filtration steps).

The next options are crucial while detecting thefts:

• Minimum fuel theft volume;
• Detect fuel thefts in motion;
• Idling;
• Calculate theft volume by raw data.

Minimum fuel theft volume

Unit properties → Sensors → FLS properties → Filling settings → 'Minimum fuel theft volume'

This option defines the required drop of the fuel level minus the fuel consumption for motion/idling so that the theft is detected.

Detect fuel thefts in motion

Unit properties → Sensors → FLS properties → Theft settings → 'Detect fuel thefts in motion'

By default, this option is disabled. In case there is a necessity to control thefts in motion a user may use the option. But if sharp fuel level drop takes place then false theft may be detected.

Idling

Unit properties → Sensors → Sensor type 'Engine ignition' → 'Consumption, l/h'
Unit properties → Sensors → Sensor type 'Absolute engine hours' → 'Consumption, l/h'
Unit properties → Sensors → Sensor type 'Relative engine hours' → 'Consumption, l/h'

The option allows you to detect thefts on stops/parkings. The system finds the difference between the spent fuel volume according to the sensors and a mathematically calculated one. In case of a non-zero difference, which is equal to or more than the value set in the minimum fuel theft volume option, the fuel theft is detected.

Calculate theft volume by raw data

Unit properties → Sensors → FLS properties → Theft settings → 'Calculate theft volume by raw data'

Similar to fillings, the filtration may deviate the start and the end fuel level values of thefts. To ignore such deviations, the system uses unfiltered data while calculating the volume of theft. This option is applied only when the value before the filtration exceeds the value obtained as a result of filtration.

Special case: How is a fuel theft detected?

Time frame of a theft and its volume

A theft is being performed.

Let us suppose that the fuel volume in the current message is V_curr, the fuel volume in the previous message is V_prev. If the difference d for the current message (d = V_curr - V_prev) is negative, the message is considered the initial message of the theft.

Time passes. When the value d is positive for some message (that is the fuel volume in the current message is higher than in the previous one), the message is considered as the final message of the theft.

A theft may be registered in the system not upon receiving the final message, but later. This depends on whether the Filter sensor values and Timeout to separate consecutive thefts settings are used for the fuel level sensor. The higher the values specified in these settings, the longer it takes to register a theft.

The theft volume equals to V_final - V_init (the difference of fuel levels between the final and the initial messages).

Theft timestamp calculation algorithm

Now we are looking for the timestamp of the theft.

The system seeks a delta with the following message (d = V_next - V_curr) for every message within the theft interval. The delta shows the decrease in the fuel level between the current and future messages.

The message timestamp that has the highest delta is considered to be the theft timestamp (in other words, the left message with the biggest delta is selected from the pair of messages).