HCK-E-S Electrical level indicators

Features and performances

The HCK-E-S level indicator with lateral connector output allows the level of intervention of the sensor to be minimised.

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 for a relatively limited time with the following liquids at a temperature of 23° C: mineral oil type CB68 (according to ISO 3498) for HCK, mineral oil type CB68 (according to ISO 3498) water or water/glycol-based solutions ( 50%) for HCK-GL, the resistance values were much higher than 35 bar.

For use with fluids other than mineral oils and under particular 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 MIN level electrical sensor

• NO: the electrical contact closes on reaching the minimum level.

• NC: the electrical contact is opened when it reaches the minimum level.

 

 

 

 

Functioning of the MAX temperature sensor

• NO: the electrical contact closes when the pre-set temperature is reached at 80°C.

• NC: the electrical contact opens when the pre-set temperature at 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

• Column level window in transparent methylmatacrylate (PMMA) for max 70°C use.

• Polyamide based technopolymer float (from HCK.127) red colour.

• NBR float (from HCK.176) black colour with AISI 316 stainless steel spiral for special executions, viscous liquids, high temperatures.

• Indicators with level visibility (quota) up to 1429 mm and fixing holes with centre distance (quota f) up to 1500 mm.

• Packing rings in special material depending on the customer's needs.

• Special screw with nickel-plated brass tap to be fitted to the lower assembly end for any maintenance operation requiring the indicator exclusion.

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.

• a) HCK-E-ST: insert the cable into the connector (standard connector) and connect the wires to terminals 1 and 2 for the operation of the MIN level sensor, to terminals 3 and ground (4) for the operation of the MAX temperature sensor. b) HCK-E-STL: insert the cable into the connector (standard connector) and connect the wires to terminals 1 and 2 for the operation of the MIN level sensor, to terminals 3 and ground (4) for the operation of the temperature probe

• 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.