EHW3-LS4 JOLA hanging electrode

Description

EHW3-LS4 The JOLA hanging electrode signals via an electrode relay the presence of a liquid medium due to, for example, a burst pipe. Floor electrodes are designed for use in dry rooms.

EHW3-LS4 with integrated galvanic separation:

• prevents interconnection of electrode circuits
• prevents the formation of earth loops when more than one detector is connected to a common power supply circuit.

The EHE -… and EHW -… conductive hanging electrodes must only be used in normally dry environments. They should be mounted in hanging mode from above (or in the case of the EHE -… type, in an upright position with a mounting stand) so that the sensor electrodes are only slightly above the floor to be monitored.

In the conductive hanging electrode EHE -… the metal housing and the concentrically arranged electrode rod in the housing form an electrode pair; the conductive hanging electrode EHW3 -… is equipped with two separate electrodes in the form of two electrode rods: 1 control electrode and 1 earth electrode. As soon as the conductive liquid creates a conductive path between the control electrode and the earth electrode, the switching state of the leakage detector shall change.

Conductive measurement principle

The principle of conductive measurement is used to detect electrically conductive liquids. Not suitable for the detection of electrically non-conductive liquids.

Electrically conductive liquids are usually aqueous solutions of salts, acids or alkalis. In water, the molecules of these substances separate into positive and negative ions, which give the aqueous solution its electrical conductivity. The conductive leak detector detects the presence of an electrically conductive liquid and then sounds an alarm.

The measurement process uses alternating current to ensure accurate response sensitivity and to prevent galvanic processes at the electrodes. The conductive leak detector shall have an integrated electronic evaluation unit with galvanically isolated circuits. This prevents the electrode circuits from interconnecting and forming earth loops if more than one of these leakage detectors is connected.

Reliable detection of liquids with poor electrical conductivity, such as condensate or demineralised water, is ensured by the factory-set sensitivity response of the conductive leak detector.

EHW3-LS4 features

• design: leak detector with relay output
• electrode plates: 2 bars of 316 Ti stainless steel, other materials (e.g. titanium, Hastelloy, Monel or tantalum) on request
• Housing: PP, other materials (e.g. PVDF or PTFE) on request
• electrical connection: four-wire connection via 4 x 0.5 connecting cable, 2 m long; equipped with halogen connecting cable on request
• supply voltage: only for connection to extra low voltage SELV or PELV! (see datasheet)
• Energy consumption: approx. 0.5 VA
• Output: potential-free quiescent current contact (NC), max. load AC/DC 5 … 24 V (very low voltage SELV or PELV only); AC/DC 1 mA … 3 (1) A; wire colours: black and dark grey
• switching condition without supply voltage: output relay de-energised, output contact open
• switching capacitor for condition detection not activated: output relay energised, output contact closed
• switching capacitor for state detection is activated: output relay de-energised, output contact open
• cable break control: control of cable breakage due to quiescent current
• galvanic isolation: only for connection to extremely low voltage SELV or PELV! voltage resistance > 500 V between capacitor circuit, supply circuit and output circuit
• max. no-load voltage across the sensing capacitors: 5 Veff 15 kHz
• max. short-circuit current on sensing capacitors: 0.2 mA
• response sensitivity: approx. 30 kΩ or approx. 33 μS (conductivity)
• temperature range: – 20 °C to + 60 °C

For more technical information, please refer to the datasheet attached under the Documentation tab.

Use case EHW3-LS4: monitoring false floors in a server room using a cable electrode and a panel electrode in an adjacent room.

Welcome to the article ”Conductive Measurement of Liquids”