Decoupling cells

Decoupling cells: overview

Decoupling cells protect insulating joints (kits or monobloc) and provide alternating-current mitigation by blocking the flow of cathodic protection DC current. On an installation, they reduce unwanted current consumption on adjacent earths.

They withstand a continuous current (AC/DC) of 100 A, an AC fault current of 2 to 50 kA (50/60 Hz, 30 cycles) and a lightning current of 100 kA (8×20 and 10/350 µs), with a DC blocking threshold of -3/+1 V or -2/+2 V optional, over a -45 to +65 °C range. The flameproof enclosures (T6, NEMA 4X, Class 1 Div 2, IP67) comply with UL, CSA, ANSI, ISA, ATEX and IECEx standards. They are installed in a box or directly on the insulating joint lugs.

The dilemma they solve

Electrical safety requires a pipeline to be connected to earth or to certain metal structures, particularly on either side of an insulating joint, to discharge faults and lightning. Cathodic protection requires the opposite, or its DC current leaks away to those structures. The decoupling cell reconciles both: it blocks the protective DC current while letting AC current, fault currents and lightning through.

When to install them

Across insulating joints exposed to surges, on pipelines running alongside high-voltage lines where induced AC must be drained, and wherever the pipeline must be earthed without losing its protection. Their certification allows installation in explosive atmospheres.

Decoupling cells: technical specifications

Decoupling cells: documentation