Pipeline Protection Device against induced AC

A high-voltage power line has a perilous impact on a steel pipeline, located nearby:

  • if a pipeline goes in parallel to a power line;
  • at intersection areas of pipelines and power lines;
  • at convergence and removal areas.
A perilous impact of a high-voltage power line on a pipeline is expressed as follows:
  1. A high-voltage power line creates an electromagnetic field which affects the underground pipeline. The result of this interaction is induction, which leads to the pipeline longitudinal electromotive force, which can lead to:
    • A threat to the personnel safety;
    • Electrical corrosion from AC;
    • Damage of electrical equipment, connected to the pipeline.
  2. In case of a high-voltage power line damage, the pipeline can be under voltage of several thousand volts.
  3. Power transmission towers are potentially dangerous in terms of atmospheric overvoltage (lightning), which requires the use of appropriate protection devices (lightning protection).
A pipeline protection device against induced AC is used to reduce a high-voltage power line impact.
A pipeline protection device is a part of pipeline electrochemical protection system against corrosion. It performs the following functions:
  • draining the induced AC from a pipeline through grounding;
  • prevention of electrochemical protection potential leakage as opposed to the standard pipeline grounding;
  • ability to measure drained AC current through the UZT built-in transformer;
  • availability of lightning protection device in accordance with GOST R 51992-2002.

Construction Description

The pipeline protection device consists of a post, an AC draining unit, a terminal block and a grounding device.

A post may be made of PVC or metal. The post is equipped with an anchor device, which prevents a test station from free taking out.

AC draining unit represents an electricity closet that contains the following devices:

  • a condensing unit for draining AC to the grounding device;
  • a lightning protection device – a gas discharger;
  • an electric transformer for drained AC measurement with 100:1 СT ratio;
  • a frequency filter (a standard version with 1100 Hz frequency); for preventing leakage of a fixed frequency AC, using the electrometric equipment.

A grounding device may consist of horizontal ground conductors, vertical ground conductors or their combination. Horizontal and vertical ground conductors represent connected sections made of stainless steel or zinc plated steel. Amount of ground conductors as well as number of sections in each of them are defined by a pipeline system project.

As an option, pipeline protection devices are made with the possibility of induced DC withdrawal. In this case, the maximum and minimum limits of permissible DC voltage are set.

Basic Specifications

Parameter Value
Maximum permissible DC voltage on a pipeline Umax[=], V 3,5
Rated drained current 50 Hz, IA [~], A (depending on UZT version) 40 or 80
Maximum drained current during 1 sec/50Hz, Imax [~], A 400
Maximum DC leakage current, if Umax= 3,5 V [=], IL [=], mA ≤1
Rated drained DC current Idc [=], A 40
Maximum rated drained DC current during 1 sec Imax [=], A 400
Operating regime Long-term,permanent
Case protection level IP34 по GOST 14254-96
Operating temperature limits:- “Md” climatic version- “Cl” climatic version from -40 0C to +60 0Cfrom -60 0C to +60 0C
Section of the grounding conductor, 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
Depth of a horizontal ground conductor, mm 4
Transient resistance of grounder and ground conductor joint, Ohm 0,05

 UZT legend:

UZT-ТSТ
XX
MC
PM/N
A/U
HkkVnnxmm
YY
MKI
K
MX
1
2
3
4
5
6
7
8
9
10

where:
1 – product name and manufacturer;
2 – XX – rated drained current, A;
3 – structural variations:

  • MC – in a metal electricity closet, fixed on a metal circular cross-section post;
  • Note: not specified, if a standard metal circular cross-section post is supplied;
  • PP – in a frame inside a PVC post of KIP square section (TU 3435-008-93719333-2012).

4 – modification with additional induced DC draining:

  • P – modification symbol
  • M/N – limits (max/min) of DC voltage on a pipeline, V.
  • Note: to specify only for modifications with additional induced DC draining.

5 – Post size: aboveground/ underground parts:

  • “1,8/0,7” – standard size, height of the aboveground part = 1,8 m,  burial depth = 0,7 m
  • “1,8/1,2” – longish size, height of the aboveground part = 1,8 m,  burial depth = 1,2 m

Note: not specified, if a standard 1,8/0,7 post is supplied.
6 – grounding characteristics:

  • H – horizontal grounder;
  • kk – number of sections in a horizontal grounder;
  • V – vertical grounder;
  • nn – number of sections in a vertical grounder;
  • mm – number of vertical grounders.

7 – YY – climatic version (Md1 – medium, Cl- cold, GOST 15150-69 (state standard)
8 – MKI – presence of a spark gap monitor module (not specified, if absent)
9 – K – distance mark (not specified, if absent)
10 – M – presence of marker plates
X – outer diameter of a pipeline, mm (not specified, if absent)
UZT are approved for operating at Gazprom and Transneft objects.