Pipeline systems and technologies

Inducted current protection device of AC / DC impact

Electrical transmission line (ETL) has a hazardous impact on a steel pipe, located nearby:

  • if a pipeline goes with parallel with ETL;
  • at intersection areas of pipelines and ETL;
  • at convergence and removal areas of pipelines and ETL.

A perilous impact of a high-voltage power line on a pipeline is expressed as follows:

1. As a result of ETL AC and DC electromagnetic field, the induced electrical voltages and currents occur in the pipeline which can lead to:

  • threat to the personnel safety;
  • electrolytic corrosion from AC and DC;
  • damage of electrical equipment connected to the pipeline.

2. In case of ETL damage the pipeline may be directly under voltage of several thousand volts.

3. ETLs are potentially dangerous in terms of atmospheric overvoltage (lightning) which requires the use of appropriate pipeline protection devices (lightning protection).

To reduce the impact of electrical transmission line a device for AC and DC pipeline protection (ICPD) is used.

Functions

Inducted current protection device is a part of pipeline cathodic protection system (CP) against corrosion and performs the following functions:

  • drains the AC / DC induced by ETL through grounding device;
  • prevents the CP potential leakage;
  • allows to measure drained AC / DC through the built-in ICPD transformer;
  • completed with lightning protection device.

Construction Description

The ICPD consists of a post, an AC / DC draining unit, a terminal block and a grounding device.

1. Post

A post may be made of PVC or metal as per the Client’s request. The post is equipped with an anchor device, which prevents a test station from free taking out the soil. 
ICPD unit modification for installation into the TS square-cross section ICPD unit modification for installation into the TS square-cross section

2. AC / DC draining unit

AC / DC draining unit contains the following devices:

  • a condensing unit for AC draining to the grounding device;
  • a protection device of atmosphere overvoltage (lightning protection) – a spark gap;
  • an electric transformer for drained AC measurement with 100:1 СT ratio;
  • a frequency filter (a standard version with 1100 Hz frequency); to prevent AC leakage of a fixed frequency when using the electrometric equipment at the pipeline.
Horizontal and vertical grounding universal connection Horizontal and vertical grounding universal connection

3. Grounding device

A grounding device may consist of horizontal ground conductors, vertical ground conductors or their combination. Horizontal and vertical ground conductors represented by sections of stainless steel or zinc plated steel connected to each other. Quantity of ground conductors as well as its sections number are defined by a pipeline system project.

As an option

As an option, ICPDs are produced with possibility to drain AC / DC. In this case, the maximum and minimum limits of permissible DC voltage are set.

Main technical characteristics:

General:

Operating temperature limits:

— “Md” climatic version

— “Cl” climatic version 

 

from – 40°C to + 60°C

from – 60°C to + 60°C

Maximum DC leakage current, if Umax= 3,5 V [=], IL [=], mA ≤ 1
AC drained unit:
Nominal drained current 50 Hz, IA [~], A (depending on ICPD version)  40 or 80
Maximum drained current during 1 sec/50Hz, Imax [~], A  400
DC drained unit:
Nominal drained DC current Idc [=], A  40
Maximum drained DC current during 1 sec Imax [=], A 400
Maximum permissible DC voltage on a pipeline Umax[=], V 3,5
Grounding device:
Grounding conductor cross-section, mm2 35
Length of a vertical ground conductor section (bar), m 1,5
Diameter of a vertical ground conductor, mm 16
Length of a horizontal ground conductor section (bar), m 2,0
Width of a horizontal ground conductor, mm 40
Thickness of a horizontal ground conductor, mm 4