HCV-S

Electrical level indicators

Features and performances

The HCV-S level indicators allow visual inspection of the level.

The HCV-ST indicators also provide an electrical signal when the maximum preset temperature value (80°C) is reached.

The HCV-STL indicators provide an analogue electrical signal of the oil temperature.

The lateral connector output allows the level of intervention of the sensor to be minimised.

Ultrasound welding to guarantee a perfect seal.

Maximum fluid level visibility even from side positions.

Lens effect for a better visibility of the fluid level.

In case of use of an extension with angled connector, the direction of the cable output is shown in Fig.1.

Technical data

In laboratory tests carried out with mineral oil type CB68 (according to ISO 3498) at 23°C for a limited period of time, the weld stood up to: 18 bar (HCV.76), 18 bar (HCV.127) and 12 bar (HCV.254).

For use with other fluids and under different pressure and temperature conditions, please contact ELESA Technical Department.

In any case we suggest to verify the suitability of the product under the actual working conditions.

 

Functioning of the sensors

• NO: Electrical contact closes when the preset temperature of 80°C is reached.

• NC: Electrical contact opens when the preset temperature of 80°C is reached.

Functioning of the temperature electrical probe (STL)

The working principle of the temperature probe is to measure the variation of resistance of a platinum element: 100 ohm = 0°C, 138.4 ohm = 100°C.

The function between temperature (T) and resistance (R) is approximately linear over a small temperature range: for example, if you assume that it is linear over the 0° to 100°C range, the error at 50°C is 0.4°C.

For precision measurement, it is necessary to linearise the resistance to give an accurate temperature. The most recent definition of the function between resistance and temperature is International Temperature Standard 90 (ITS-90). The function between resistance and temperature, obtained in laboratory tests, measuring directly the resistance value on the contacts is shown in the graph. We suggest, anyway, to set the system in order to compensate both heat dissipation and cable resistance.

The temperature variation of 1°C causes a 0.384 ohm variation in the probe resistance. Therefore, even a small error in the resistance measurement (for example, if the resistance of the cables connecting to the probe were not considered) translates into a significant error in the temperature measurement.

Because of the low signal levels, it is important to keep any cables away from electric cables, motors, switchgear and other devices that may emit magnetic or electrical noise. Using screened cable, with the screen grounded at one end, may help to reduce interference.

Furthermore, if long connection cables are used, make sure that the signal measurement and reception device is designed to compensate for the resistance of the cables themselves.

 

 

 

 

 

Special executions on request

• Level indicators with stainless steel screws, nuts and washers.

• Level indicators HCV.76 with screws M12.

• Level indicators for use with fluids containing alcohol.

• UV resistant transparent technopolymer level indicators.

• MAX temperature electrical sensor with trigger threshold at 70°C or 90°C.

Accessories on request

FC.M12x1: extensions with 4 pole M12 female axial connector.

Female connector assembly instructions

• Remove the connector from the indicator by unscrewing the set screw placed on the connector, take the contact holders out and loosen the cable gland.

• Insert the cable into the connector (standard connector) and connect the wires to terminals 3 and ground (4) of the contact holder.

• Assemble by pressing the contact holder into the connector in the required position.

• Screw the connectors to the indicator and then tighten the cable glands.