Solid-State Decoupler (SSD)

I. Overview

With the more and more extensive use of cathodic protection technology for buried steel pipelines, the stability of the cathodic protection system has also attracted much attention.

However, electromagnetic interference is ubiquitous in real production life, and the influence of electromagnetic interference on pipeline cathodic protection system also exists. Because electromagnetic interference causes cathodic protection function failure, accelerated corrosion, damage to the applied current equipment cases are common, so the solution to the interference problem has become one of the very important issues in the cathodic protection system.

Usually, the solution of electromagnetic interference is to install discharge device on the pipeline, which can effectively solve the electromagnetic interference problem and limit the pipeline potential to a reliable level. However, there are some problems with the existing current discharge device, for example, it can only tolerate electromagnetic interference with a relatively small amplitude, and it cannot solve the interference of strong energy such as direct lightning current and induced lightning current.

Solid state decoupler can well solve the high voltage line fault ground short-circuit current, high voltage line on the upper end of the lightning line by lightning introduction of ground current, train through the railroad when the stray current. This product can protect the over-voltage or over-current generated by the above situations on the cathodic protection of pipelines, prevent pipelines from electromagnetic interference and aggravate corrosion, and play an effective role in protecting pipeline equipment.

Practical Application

1. Electrical Equipment Grounding System Decoupling
   The cathodic protection systems, which are commonly applied on buried pipelines, underground storage tanks or other metallic structures, prevent galvanic corrosion by applying a low voltage negative DC bias to the structure. However, required safety grounding systems connected to the structure short this CP current to ground and may compromise the efficiency of the CP system.Installed between the protected structure and the grounding system, our solid state decoupler isolate or block the flow of DC current to the grounding system or other equipment, thereby eliminating any negative influence on your CP system caused by the grounding materials or neighboring equipment.
2. Insulated Joint Over-voltage Protection
   Isolation joints often need over-voltage protection against lightning and AC fault current, and in some cases, steady-state induced AC voltage. The AC fault current generated by a failure of nearby equipment can be transmitted through a pipeline, endangering personnel or causing damage. When an AC fault occurs, our solid state decoupler instantly conducts fault current to ground, taking the AC current away from the pipeline for immediate protection.
3. Lightning Protection
   When a lightning strike occurs, it presents a safety hazard to personnel and pose a risk to nearby pipelines. The solid state decoupler behaves in the same way as it does during an AC fault. It channels the high voltage DC current of the lightning to ground, safely protecting nearby workers and the pipeline. As soon as this event has ended, the solid state decoupler automatically switches back to its DC isolation mode.
4. AC Voltage Mitigation
   Many pipelines are usually buried along a shared right-of-way with overhead high-voltage power lines, inducing AC current in the pipeline. It normally causes corrosion and related issues. Our solid state decoupler can collapse the steady-state voltage between the connection points to a negligible level by continuously conducting induced AC current to ground, while simultaneously leaving your cathodic protection system unaffected.

II. Cited standards

·IEC61643.1-2005

“Surge Protectors for Connection to Low Voltage Distribution Systems Part 1: Performance Requirements and Test Methods”

·NACE RP0177

“Measures to mitigate the effects of alternating current and lightning on metal structures and corrosion control systems”

·GB18802.1-2011/IEC61643-1

"Surge Protectors (SPD) for Low Voltage Distribution Systems Part 1: Performance Requirements

and Test Methods".

·GB/T19271.1

"Protection against Lightning Electromagnetic Pulse (EMP) Part 1: General Principles".

·GB50057  Lightning Protection Design Code for Buildings

·GB50251  “Gas Transmission Pipeline Engineering Design Code”

·GB50253  “Design Code for Oil Pipeline Engineering”

·GB4208 “Case Protection Level (IP Code)”

·GB/T2423  “Environmental Tests for Electrical and Electronic Products”

·SY/T0032-2000  “Technical Standard for AC Discharge Protection of Buried Steel Pipelines”

III.Performance Parameters

IV. Technical specifications

V. Installation instructions

1、Connect one end of the product to the pipeline and one end to the grounding network,

and the grounding resistance value of the grounding network should be controlled within 4 ohms.

2、This product can be installed in explosion-proof environment by adopting explosion-proof

box structure.

3、This product adopts sealed structure and can be installed in wet place.

VI. Maintenance

This product is a maintenance-free product, but in the event of direct lightning and other strong current impacts increase in the number of times (more than 15 times), the product will have the possibility of deterioration, deterioration that is, the product is damaged and out of action.

The product should be opened periodically to check the resistance of the product terminals at both ends, if the resistance value of the ohm level, the product should be overhauled or replaced in a timely manner.