Reference Electrodes

A reference electrode is an electrode with a stable and reproducible potential, which can be used for other electrode potentials measurement. Stationary reference electrodes are used to monitor and control the level of cathodic protection.

STELTH stationary electrode is designed for underground operation and does not require special filling, as well as for water (liquid) and flooded areas operation. At the same time a reference electrode maintains stability in dry desert soils and high moisture soils. Freezing does not affect the efficiency of the reference electrode.

Advantages and features of RE-TST-STELTH-P40 reference electrodes.

  • Production tests of each reference electrode, based on 8 parameters.
    Each electrode has a serial number and a test certificate supplied with the shipment.
  • 100% Electrolyte Solid Chemical State Form (without inactive or inert carrier).
    The presence of a solid-state electrolyte is required to achieve a 30-year lifetime. There is no more need for support materials such as gel or gypsum, which reduce the useful volume and degrade the technical characteristics of the electrode.
  • Hydrogen sulfide sensor (a part of a reference electrode).
    It provides an opportunity to evaluate the reference electrode and its surrounding conditions under the influence of hydrogen sulfide with no need to remove the electrode, or send it to a lab for analysis.
  • Moisture retention membrane.  The MRM prevents contaminated ground water from entering the reference electrode.
  • Chloride Ion Trap. One of the main reasons for the reference electrodes fault is chloride contamination. The first line of protection is a membrane, which traps the chloride ions in contact with the membrane. The second line is ion trapping technology implemented in the chemical composition of the electrolyte, which serves as a “molecular sponge”, that traps chloride ions before they can affect the sulfate in the electrolyte.
  • Hydrogen Sulphide Ion Trap. Sulfides have an increasing destructive effect on the reference electrodes due to expansion of industrial areas and dumps, which leads to the formation of hydrogen sulfide (H2S) in the soil. Ceramic touch zone at all STELTH reference electrodes contains a special composition of the trap to neutralize these ions.
  • Large copper electrode surface square (123 mm2). Allows to reach high operating stability of the reference electrode, to reduce hysteresis and prolong its service life.
  • Large square of the sensitive surface (838 mm2). Allows to obtain a high sensitivity, to reduce the voltage drop across the resistance between the reference electrode and its surrounding soil.
  • Reuse. Without exception, all the reference electrodes have an indefinite shelf life and provide for the possibility of commissioning, decommissioning, and then re-use at any time sequence during the service warranty period.
  • Freezing up to -40 ° C.
  • High stability in desert and flooded soils.

RE legend:

1 – RE name/trade mark;
2 –  type of reference electrode:
– «Cu» symbol – copper-copper sulfate RE;
– «Ag» symbol –silver-silver chloride RE;
– «Zn» symbol –  zinc-zinc sulfate RE,
3 – model No, according to the table ;
4 – measuring cable length, m.;
5 – “AES ” symbols – presence of the coupon (not specified, if absent):
– “AE” – coupon;
– «S» – operating surface square, cm2.


Example of RE designation:

“Reference electrode RE – TST- Stelth – P40 -Cu-007-6- AE1 TU 3435-016-93719333-2013” .

 RE Types RE-TST-Stelth

Model No Application Conditions Type (electrolyte and bar materials) Moisture retention membrane
001 Stationary – Laying into fresh groundwater soil, not contaminated with chlorides Cu-CuSO4 Yes
002 Stationary – Fresh or potable water feed, rich soil, no chloride contamination Cu-CuSO4 Yes
003 Stationary – Laying into salt or hard groundwater soil with chlorides Ag-AgCl No
004 Stationary – Salt or hard water feed, rich soil, contaminated with chlorides Ag-AgCl No
005 Stationary – Laying into fresh water flood zone, no chloride contamination Zn-ZnSO4 Yes 
006 Stationary – Fresh or potable water feed, rich soil, no chloride contamination Zn-ZnSO4 Yes
007 Stationary – Laying into soil without chlorides Cu-CuSO4 Yes
007C Stationary – Laying into soil without chlorides for installation of above-ground storage tank Cu-CuSO4 Yes
008 Stationary – Laying into soil with the chloride contamination Ag-AgCl No
009 Stationary – Laying into soil without chlorides Zn-ZnSO4 Yes
019 Stationary in a concrete frame – Laying into soil in concrete frames, without chlorides Cu-CuSO4 Yes
020 Stationary in a concrete frame – Laying into soil in concrete frames, with chloride contamination Ag-AgCl No
021 Stationary in a concrete frame – Laying into soil in concrete frames, without chlorides. Zn-ZnSO4 Yes


Copper-copper sulfate reference electrodes


Sensitive surface square

838 mm2

Copper bar surface square

123 mm2

Average size of sensitive zone voids

17 mcm

Stability on 3 mcA load

5 mV

Internal resistance

48 Ohm

Operating temperature limits

– 18…+85 °С

Storage temperature limits

– 40…+85 °С

Overall dimension , length/diameter

20 cm / 5,1 cm

Min. projected service life

30 years

Shelf-life (without conditions limitation)



  • Square of operating surface – 1 сm2
  • Cable length – 7 m
  • Electrode material – pipe steel
  • Control parameters (PKM-TST subsystems):
    • Polarization potential;
    • DC (protective), structure – AE;
    • AC, structure – AE;
    • Density of DC and AC;
    • AC spreading resistance.