Fuel fillings and thefts can be detected only if a unit has fuel level sensors and has the Fuel level sensors option activated. Fuel consumption is calculated if there are fuel consumption sensors. The determination accuracy depends on the accuracy of the installed sensors as well as on their correct configuration. The parameters adjusted on this tab are used during the calculations. For your convenience, they are divided into several sections.

Fuel fillings/thefts detection

Minimum fuel filling volume

The minimum increase of the fuel level that should be considered a filling.

Minimum fuel theft volume

The minimum decrease of the fuel level that should be considered a theft.

Ignore the messages after the start of motion

This feature allows skipping the indicated number of seconds at the beginning of the movement when due to different factors the received fuel level data may not be very accurate. The beginning of the movement is registered when the minimum moving speed set in the Trip detection tab is achieved.

Minimum stay timeout to detect fuel theft

The minimum duration of the interval with no movement, followed by a decrease in the fuel level in the tank for more than the minimum fuel theft volume indicated above.

Timeout to separate consecutive fillings

The system can sometimes detect more than one fuel filling during a short time interval. In such cases, they can be combined in one if the time between them (timeout) does not exceed the time specified in the setting.

Timeout to separate consecutive thefts

This feature is similar to the previous one. Thefts are not summed up if the timeout is exceeded and if the fuel level has increased between them.

Detect fuel filling only while stopped

When this option is activated, fuel fillings are detected only at stops, that is, when the speed of the unit is lower than the minimal speed indicated in the trip detection. This allows reducing the number of false fillings which may be caused, for example, by fuel level fluctuations during the movement.

The initial fuel level is taken from the first message without movement or from the last message with movement.

If you type a certain value in the Timeout to detect final filling volume field, the system also detects fillings during this period after the end of the stop.

Timeout to detect final filling volume

in the process of filling there can be interruptions. This option appears if the previous one is selected and allows to set the duration of such interruptions. In this case to determine the fuel level after refuelling, not the last message that corresponds to a filling is used, but the one that follows the indicated timeout.

Detect fuel thefts in motion

Traditionally, fuel thefts are searched during the stops. This feature allows searching for them during the motion, too. For example, it may be useful for ships. However, in many cases, it may cause the detection of false fuel thefts due to probable fuel level differences while, for instance, moving on rough terrain.

Time-based calculation of fillings

It is recommended to use this calculation method for the units with high fuel consumption during the idling (generator, tower crane, etc.). When it is activated, the whole time period is taken into account regardless of trips/stops.

Time-based calculation of thefts

The feature is similar to the previous one, only applicable to fuel thefts.

Calculate fuel filling volume by raw data

With this feature activated, the initial and the final fuel levels on the interval corresponding to the fuel filling are replaced with the values from the messages before applying the filtration. This occurs only when the value from raw data exceeds the value obtained as a result of filtration.

Calculate theft volume by raw data

With this feature activated, the initial and the final fuel levels on the interval corresponding to the fuel theft are replaced with the values from the messages before applying the filtration. This occurs only when the value from raw data exceeds the value obtained as a result of filtration.

Fuel level sensors

When this type of sensors is used, the fuel consumption is determined on the basis of its level in the tank according to the following formula: [fuel level value at the beginning of the interval] − [value at the end of the interval] + [fillings] − [thefts] (if the Exclude thefts from fuel consumption option is activated in the report settings).

Replace invalid values with math consumption

If the feature is activated, in case of erroneous values on an interval they are replaced by the values calculated mathematically. The mathematical calculation uses the data indicated in the properties of ignition, relative and absolute engine hours sensors (option Consumption, l/h) and the value of the engine efficiency sensor.

Time-based calculation of fuel consumption

If the option is enabled, while calculating the fuel, all the time is taken into consideration, it does not matter whether the unit has been moving or not. If it is disabled, the fuel level during the intervals with no motion is not considered during the calculations.

Filter fuel level sensors values

This feature allows applying median filtering to the received values of the sensor to exclude data emissions (sudden increases or decreases). The minimum filtration level is 0 (zero) — with a smoothing of 3 messages. Then all the filtration levels from 1 to 255 are multiplied by 5 to determine the number of messages which are used for smoothing. Therefore, the higher the filtration level is, the more the fuel chart is approximate to a straight line, that is why it is not recommended using the filtration level higher than 8 (the optimum is from 0 to 3).

Impulse fuel consumption sensors

Two types of impulse fuel consumption sensors are used in Wialon: simple accumulative and with overflow (on reaching a definite value, the impulses counter resets and the calculation restarts from zero). It is not practical to use the first type, while the sensors with overflow are widely spread.

This calculation method takes into consideration the values of the sensors from the previous and the current messages: the previous value is subtracted from the current one and, if needed, the calculation table is applied to the received value. The sum of the values received on the interval corresponds to the amount of the fuel consumed.

Every sensor of this type must have a calculation table from impulses to litres (gallons).

Two options are available in this section:

Max impulses

If there is a limit after which the impulse counter is zeroed (overflow), it can be indicated in this field. However, with this limit adjusted in case of an emergency reset, the calculations will be meaningless.

Skip first zero value

If this option is activated and the value of the Max impulses field is 0, the difference between the current and previous sensor values is taken into account when calculating the fuel consumption. If the value of the Max impulses field is non-zero, the Skip first zero value option is not taken into account when calculating the fuel consumption.

Absolute fuel consumption sensors

The sensors of this type show the fuel consumption during all the period of vehicle operation. AbsFCS values increase all the time, so the overflow of such a sensor is not expected.

The fuel consumption is calculated in the following way: the sensor's value at the beginning of the interval is subtracted from the sensor's value at the end of the interval and, if needed, the calculation table is applied (to every sensor of this type individually).

Instant fuel consumption sensors

If this type of sensors is used, the hardware sends messages that contain the amount of the fuel consumed from the previous message till the current one. Accordingly, to determine the fuel consumption on an interval, the values of the InsFCS are summed.

For instance, the hardware has sent three messages with the following values: х1 = 0,01 l, х2 = 0,023 l, х3 = 0,048 l. The fuel consumption during this interval is: х1 + х2 + х3 = 0,01 + 0,023 + 0,048 = 0,081 (l).