Capacitive fuel level sensor EPSILON EN is intended to measure the fuel level in the vehicles tanks. Sensor keeps all the functions of EPSILON ES sensor alongside with new functions. In the EPSILON EN there are modifications with digital RS-232, RS-485, frequency, analog (with FV-1x converter) inputs.
Main advantages of the EPSILON EN sensor:
- Modular construction.
- Measuring head is mounted and dismantled independently of the fuel probe that allows easily and quickly to change, if necessary, the measuring head without re-calibration of the tank;
- Presence of the inclinometer. Designed to provide information about tilt angle of the vehicle. Inclinometer allows to get information about validity of measurement and to perform correction and compensation using 3D model of the tank;
- Built-in concentrator. Possibility to plug in multiple sensors with digital interfaces and to determine the total fuel level in several tanks of the vehicle;
- The measuring part is isolated galvanically;
- Explosion-proof type 1ExsiallCT6 X;
- Wide range of possible probe length. The sensor with the length of 770mm can be cut down up to 30mm;
- Non-standard length up to 3000mm; Supports a version of the absolute linear scale and a version of the relative measurement of the capacity of the tank (the measurement with only two extreme points of calibration);
- Remote update of the configuration parameters and firmware;
- The possibility to choose a “string in tube” or “tube in tube” construction.
Sensor description
Inside the sensor measuring head is the level converter, digital signal processing circuit, the data exchange device, voltage regulator and circuit, providing the necessary protection for the input and output circuits. Connection with external devices is provided via cable.
The measuring of the fuel level is provided by the measuring head with the probe, which is immersed into fuel. The probe is a coaxial capacitor formed by an aluminum tube (outer electrode) and insulated copper string (inner electrode). The necessary tension of the string is supported by a spring which is located in a contact connector of the probe.
The mounting of the sensor is performed using self-drilling screws, flange fixing probe (together with a gasket) on the tank. Tightness of the measuring head is provided by O-ring seal located in the front groove.
Protection of the interface cable from mechanical effects is provided by a flexible metal hose.
Safety of the sensor is provided with the application of:
- intrinsically safe measuring circuit with normalized values of voltage, inductance, capacitance and resistance;
- multi-layered security and front-end supply chain;
- metal shell of the measuring head with a proper degree of protection (IP-68 according);
- compound filling the shell of the measuring head.
Operation principle
Sensor probe immersed in the fuel acts as a variable capacitor, whose capacity is linearly dependent on the level of its filling with fuel.
The sensor measuring head performs a linear transformation, capacity of the probe into a digital code-level fuel, processing of the digital data by averaging the results of measurements, temperature measurement of fuel tank and issuance of data in a uniform protocol for EDE RS-485 or RS-232 or analog signals (only the level), depending on the model.
Data on the fuel level may be issued in the form of 10-and 12-or 16-bit value, the temperature data - in the form of an 8-bit value.
Calibration procedure is performed by specialists of RCS or its authorized dealers to install the sensor on the vehicle.
Installation of the sensor
The sensor is mounted in the center fuel tank, as shown in the figure. Only in this case, the tilt acceleration or deceleration of the vehicle fuel level in the measuring point of the least subject to fluctuations. The probe should be oriented vertically downward.
If the tank top difficult to obtain, it is necessary to remove the tank from the vehicle to perform proper installation the sensor.
The sensor is screwed into the threaded hole of the flange as shown in the figure. Tightness is ensured by a rubber O-ring groove located at the end of the measuring head.
After the installation the sensor is sealed:
Tank calibration
To ensure accurate monitoring of fuel, the tank should be calibrated: initially empty (full) tank is filled (merged) in equal portions, with fuel, and with the help of special software ES Install it is measured and recorded by the sensor after adding (draining) the each serving.
To achieve the most accurate performance of the probe is desirable to “train” the sensor. It is desirable to perform the calibration procedure not immediately after installing the sensor, but some time later, after the vehicle's mileage is corresponding with the expenditure of fuel in the 50 ÷ 70% of tank capacity. During this time, normalized by mechanical clearance, provided by a rubber gasket flange and a polymer sealant, and the entire surface of the probe forms a stable dielectric layer of fuel.
If the "training" of the sensor is not possible, then before the calibration of the tank, by the method of filling, using a new sensor (the probe) to immerse the probe into the fuel, remove and allow the fuel to drain for 20 -30 minutes. If the calibration is performed by draining, then the specified procedure is not needed. At the time of calibration of the sensor must be disconnected from the onboard controller and connected to the PC. At the end of the calibration connection to the onboard controller should be restored.
The result of calibration in the form of tank calibration tables and the credentials of the work performed is saved in PC format, which provides data transmission in the control software.
Technical characteristics
| Description | Unit | Value | Notes |
|---|---|---|---|
| General | |||
| Valid values of electrical conductivity controlled by the fuel, not more then | cm/m | 10-8 | 2 |
| Temperatures range | °C | -40...+75 | |
| IP level protection of probe head | IP68 | сертификат взрывозащищенности | |
| Measurments | |||
| The range of measured values of the position of the controlled fuel | mm | От 10 до 910 | 1,3,4,5 |
| The resolution of the measurement of diesel fuel in the static mode, not worse then | mm | 0,05 | 6 |
| The basic allowable error level measurement in a static mode, not more then | mm | 0,5 | 7 |
| The average period of measurement results in dynamic mode | с | 8 | |
| Bit code representation of measurement results | bit | 10/12/16 | Level (8) |
| 8 | Temperature | ||
| Power Supply | |||
| Supply voltage, the operating range | V | +12-4 ÷+24 +12 | Nominal |
| +80 | Limited | ||
| Current consumption | mA | 5,5±0,5 | With 12V |
| 2,5±0,2 | With 24V | ||
| Mode | Constant | ||
| Acceptable impact of pulsed voltage on power circuits | ± 200V, 1s ± 1100V, 1 ms |
9 | |
| Interface | |||
| Digital | RS-485 | General | |
| RS-232 | 10 | ||
| Analog | 11 | ||
| Installation size and weight | |||
| Execution of planting flange | SAE, 5 holes d=5mm |
12 | |
| Type the thread probe | М25х1,5 | ||
| Size of the hexagon wrench for the measuring head | mm | 36 | |
| The height of the measuring head over the surface of the tank, including the planting flange, not more then | mm | 29 | 13, 14 |
| Weight of the sensor, not more then | gr | 250 | 4, 14 |
