Brief Description of the Set-Up and Activities of the Power and Telecommunication Coordination Committee (ptcc)




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Telecommunication Research Center

  1. Shri Tej Singh, Asstt. Director (SE)


(ii) NTPC

  1. Shri M.Barat, Engineer (T)

  2. Shri R.S. Moni, Engineer (PS-HVDC)

  3. Shri Rebati Dass, Engineer (PS-HVDC)



(iii) Central Electricity Authority

  1. Shri D.M. Rao, Dy. Director (PTCC)

  2. Shri Ram Swarup, Dy. Director (PTCC)

  3. Shri D.K. Malik, Asstt. Director (PTCC)

Appendix VIII to Chapter 1

(Refer Para 6.2.6)
Recommendations Based On the Minutes of the Meeting Held between Delhi Electric Supply Undertaking (DESU) and Department Of Telecommunications Held on 23rd March 1987


  1. (i) Para 6.3.2, Page 16 of IS: 1255/1983

Due to various practical difficulties, particularly the aspect of pushing up the cost of laying of cables in case of increased depths, depths as proposed by Telecommunication Department, are not accepted. The existing depths as provided on Page 16 of IS: 1255 may stay.


(ii) For Road crossing of all Cables.
The cable shall be laid through the adequate size of pipes crossing the road.
Along the roadside concrete covers with marking on all cables of 11 KV and above shall be provided. (The present practice is that for 11 KV cables bricks are provided to cover the cable, which is considered not an efficient and durable arrangement).
2. (i) Para 6.3.3 – Clearance

In Delhi it may be difficult to obtain proposed clearance of 0.6 meters between Power Cable and Telecommunication Cable due to pressure on space allocated for routes to provide various underground services, hence it may not be possible to achieve. However, in other places in India wherever it could be achieved should be provided. Accordingly, it was agreed that Para on Clearances should be reworded as under:


- Power Cable to Preferably 0.6 meters but not less than 0.3

communication cable meters at any point.




  • For identification of the underground cable provision for route markers should be made suitably to read as under




  • Route Markers – Suitable route markers/indicators indicating disposition of the cable be provided.


Note: Para 6.3.2 and 6.3.3 of IS: 1255/1983 is reproduced below for ready reference.
6.3.2 Depth
The desired minimum depth of laying from ground surface to the top of cable is as follows:
High voltage cables, 3.3 KV to 11 KV rating : 0.90 m

High voltage cables, 22 KV, 33 KV rating : 1.05 m

Low voltage and control cables : 0.75 m

Cables at road crossings : 1.00 m

Cables at railway level crossings (measured

from bottom of sleepers to the top of pipe) : 1.00 m


6.3.3 Clearance
The desired minimum clearances are as follows:
Power Cable to power cables : Clearance not necessary; however,

Larger the clearance better would be current carrying capacity.


Power cables to control cables : 0.20 m
Power cable to communication cable : 0.30 m

Power cable to gas/water main : 0.30 m


Inductive influence on sensitive control cable on account of nearby power cables should be checked.

Appendix IX to Chapter 1

(Refer Para 6.3.7)
Protection of Telecommunication Line from

High Induced Voltage with Gas Discharge (GD) Tubes

by using 20 GD Tubes Formula


    1. Introduction

Owing to vast expansion in Power & Telecommunication sectors number of power lines happen to run parallel to telecommunication lines. Telecommunication lines, therefore, need to be protected from low frequency induction in the event of single line to ground fault on paralleling power lines when the induced voltage exceeds the prescribed safe limit of 430 volts. Telecom personnel working on these circuits and the equipment installed need also to be protected from the influence of hazardous potentials.


One of the measures commonly adopted is the installation of Gas Discharge (GD) Tubes on telecom lines in paralleling section. Under the normal conditions, the telecom line is kept insulated from earth by it. When the induced voltage exceeds the striking voltage of the GD tube, it conducts and offers low resistance path to earth, bringing down the induced voltage to safe limits.
Dividing the induced voltage by 300 volt and rounding them off to next higher number generally arrive at the number of GD tubes installed. One GD tube each is installed at both ends and the remaining are placed at equidistance intermediate points on telecom line in the paralleling section. This procedure is adopted where the induced voltages are in the range of 430 to 2000 Volts. When the induced voltage is 2000 Volt or more then the number of GD tubes is to be arrived at by using 20 GD tubes formula.
2.0 Formula
As per 20 GD tubes formula, the number of Gas Discharge Tubes required to be installed on telecom line for protection against induced voltage can be calculated as under:


  1. For high reliability power line (more than 33 KV) :

  2. For low reliability power line (up to 33 KV) :

Where E = Induced Voltage in volts.

N = Number of Gas Discharge Tubes required

Z = Total Impedance of effected portion of telecom line in ohms.
Again

where is Impedance per kilometer of telecom line in ohms per km.



is Length of parallelism in km.

is in ohms per km. for different wires:
5 AWG ACSR 0.65 ohms/km

7 AWG ACSR 0.704 ohm/km

300 lbs/mile copper 0.66545 ohms/km

242 lbs/mile copper weld 0.89 ohms/km

300 lbs/mile iron wire 1.522 ohms/km

100-lbs/mile-iron wire 4.27 ohms/km


The above cited formula was accepted by Department of Telecommunications vide DG P&T letter No. 130-21/83-TPL (TX) dated 6th August 1983.


    1. Limitations




    1. This formula should be applied only in such cases where the induced voltage is 2000 V or above.




    1. By applying this formula, the maximum number of Gas Discharge Tubes, which could be permitted to be installed on a telecom line for protection against induced voltage, is restricted to 20 (Twenty) only. Provision of more than 20 GD tubes on a telecom line leads to degradation of ‘Quality of Speech’ including increase in ‘Cross-talk’.

If the number of GD tubes exceeds 20, it becomes a case of re-engineering in which either the affected telecom lines are to be shifted to a safer distance to bring induced voltage within permissible limit or media of communication is to be changed.


3.3 Since increase of Noise and Cross-talk up to installation of 20 GD tubes is within permissible limits as tested by TRC, New Delhi, Department of Telecommunications, Government of India, has permitted the use of 20 GD tubes for protection because power sector were vehemently pressing for increase of induced voltage limit from 2000 to 6000 V.


    1. Example

DANTEWALA - SUKMA LINE

1 pair - 5 AWG
Length of parallelism with high reliability power wire = 35.18 miles
Induced voltage on telecom line due to

high reliability power line = 2430 volts


Calculation for ascertaining requirement of GD tubes to bring induced voltage within permissible limits.



Line Impedance = 0.65 ohm/km.


L = 35.18 x 1.6 Kms.


Z = 35.18 x 1.6 x 0.65















`

Say, 10
Substituting for


=243 9(1+ 1.6532)
= 644.73685

Say, 645 Volts


Thus number of GD tubes required to be fitted on telecom line to bring induced voltage within permissible limits = 10 (Ten) only.

Appendix X to Chapter 1

(Refer Para 6.4.6)
Chief General Manager, T&D Circle, Jabalpur Letter No.TD/LP-2091 Dated 23.4.1982
Subject: ‘Time Limit’ for Various Steps Involved in PTCC Clearance
Reference: Para 3.13 of the Minutes of the Central PTCC Meeting No.4/81-82/Ranchi dated 31.3.1982 Circulated vide TD/LP-2015 dated 8th April 1982.
The Central Power and Telecommunication Co-ordination Committee meeting held at Ranchi on 24th February 1982 has approved for adoption the Recommendation No. PTCC/BY/Sub-committee/Misc dated 23rd November 1981 of the Sub-committee in respect of Time Limits to be observed by different agencies for completion of various steps involved in the clearance of cases referred to PTCC.
These recommendations are given in the Annexure to this letter. It is requested that the concerned field units of your Circle District may kindly be apprised of these and directed to adhere strictly to these time limits forthwith and thereby ensure speedy clearance of cases referred to Power and Telecommunication Co-ordination Committee.
Sd/-

DET(P)


For General Manager

Annexure to TD/LP-2901 Dated 23rd April 1982 – ‘Time Limits’



  1. For obtaining PTCC route approval




  1. For Approval of 11 KV Lines – Approval by the respective DEs (Telecom)

  1. 8 weeks if the power line proposal pertains to single case.

  2. 12 weeks if the cases are referred in-group.


(ii) For 22 KV/33 KV Power Lines – Approval by the State Level

(a) Furnishing the telecom details by P&T/ 10 weeks

Railway/Army etc.
(b) Examining cases and computing the 3 weeks

Induced Voltage (IV) calculations and

forwarding the same to Railways, if required.
(c) Forwarding recommendations by Railways 4 weeks
(d) Final examination and issue of certificate 3 weeks

(iii) For 33 KV D/C and above up to 132 KV Power Lines (Central Cases)
(a) Furnishing telecom details by P&T/ 12 weeks

Railway/Army


(b) Scrutinizing the details, preparing copies 2 weeks

& forwarding to concerned Electricity

Board by DET PTCC.
(c) Furnishing I.V. calculations by Electricity 10 weeks

Board and endorsing copies to all concerned


(d) Furnishing recommendations by Railway /Army 4 weeks

(e) Final examination & Issue of certificate 4 weeks


(iv) For Approval of Power Lines above 132 KV (Central Cases)
(a) For furnishing telecom details by 12 weeks

P&T/Railway/Army.


(b) Scrutinizing the details, preparing 2 weeks

additional copies and forwarding to

Joint Secretary Power.
(c) Furnishing Induced Voltage 10 weeks

calculation by Joint Secretary Power &

endorsing copies to all concerned.
(d) Furnishing recommendations by Railway/ 4 weeks

Army.
(e) Final examination and issue of certificate 4 weeks





  1. For approval of Cases from P&T/Railway/Army for the construction of Telecom Lines, laying Coaxial Cables etc.




  1. For marking and furnishing power line

details of various categories of power

lines separately to the AE (PTCC)

(up to 33 KV) to the concerned Electricity

Board authority (for cases of 33 KV D/C

and above up to 132 KV) and to the Joint

Secretary (Power), C.E.A. (for cases

above 132 KV) 12 weeks

(b) Computing Induced Voltage calculation

by AE (PTCC)/Electricity Board/Joint

Secretary (P). 10 weeks


(c) Furnishing recommendations by Railways/ Army 4 weeks
(d) Final examination and issue of certificate 4 weeks.


  1. For protective works after the PTCC approval




  1. For quoting the charges and furnishing

Estimate 8 weeks

(b) Arrangement for payment 8 weeks

(c) Execution of protective works by P&T 10 weeks

(d) Execution of protective works by Railways 10 weeks


Notes:


  1. In general, the time schedule recommended for the various functions shall not apply to cases where re-engineering is involved. Even for such cases the appropriate authorities may quote the reasonable time required for the re-engineering.




  1. The period for implementing the protective works has been recommended assuming the essential materials for those works would be available in reasonable time.




  1. If the protective works are to be undertaken by the Department or Agencies other than the Unit submitting the proposal, every attempt should be made for speedy completion of the protective works. However, energization shall not take place if the protections are not completed.




  1. The time prescribed may be taken as maximum.




  1. For watch and monitoring




  • Cases below 33 KV: - Necessary monitoring and watching would be done by the respective State Level PTCC Committees.




  • The Standing Sub-committee will examine badly delayed cases of 33 KV D/C and above.




  • Information pertaining to such cases would be called for in the prescribed form from the various DETs (PTCC) for review by the Sub-committee.

PROFORMA

Appendix XI to Chapter I

(Refer Para 6.4.7)
Government of India

Power & Telecommunication Co-ordination Committee
No………… Date…………

Certificate of Approval to the Route of Extra High Tension (EHT) Power Line / Telecommunication Line

Approval of the Power & Telecommunication Co-ordination Committee is hereby conveyed to the route of …………………………….EHT Line/Telecommunication Line/Cable particulars of which are given in Annexure I.


The approval is for the route only and is subject to the following conditions.
1. The approval is based on the Power system/Telecom system conditions’ details as reported by the Power supply authority/Telecom authority at present. Any changes either to Transmission line or the Power system or the paralleling telecommunication lines which are likely to alter the low frequency induction from the estimated at present should be reported to PTCC for its prior approval.


  1. The Power and Telecommunication authorities shall be required to adopt such measures as may be recommended by PTCC for counteracting any interference that might arise when the EHT line is in normal operation.




  1. Each crossing should satisfy the condition as laid down in Para 6 -10 of PTCC Code of Practice for crossings.




  1. The angle of crossing shall be 90 degree but in no case less than 60 degree.




  1. The power line shall be equipped with protective switchgear such that the duration of earth current shall be as short as possible but never exceeding 0.5 seconds.




  1. The power line shall be energized within a mutually acceptable time limit after obtaining a Certificate from concerned Telecom and/or Railway authority regarding completion of provision of all protective measures as recommended by PTCC and also under specific clearance from the Telecom and/or Railway authority maintaining the Telecom system.




  1. The energization of Extra High Tension power lines would not be held up for want of installation of GD tubes on telecom lines when the induced voltages are in the range of 430 to 650 V.

  2. The telecom line shall be commissioned within a mutually acceptable time after completing provision of all protective measures as recommended by PTCC and also after obtaining a specific clearance from Power authority, if certain measures as recommended by PTCC are to be carried out on power system.




  1. The later entrant in the field shall bear entire cost of providing GD tubes and their fitting as recommended by PTCC including 15% spares and/or any other protective measures as recommended by PTCC.




  1. The route approval shall be subject to special condition as laid down under Annexure II.

Joint Secretary (Telecom)

Power & Telecommunication Coordination Committee.

Note:



  1. Proforma for Annexure I, separate for Power Lines and Telecommunication lines is given in the following pages. For Cables, the same proforma may be used with suitable modifications, where necessary.




  1. Special conditions, if any, may be separately listed and enclosed as Annexure II.


Annexure I

(For Power Lines)


  1. (a) Name of the Power Supply authority seeking approval

(b) Reference number & date:

(c) Probable date of energization:




  1. (a) Name of the power line:

(b) Route map number & date:

(c) Operating voltage:

(d) Length of HT line:

(e) Number of circuits:


3. (a) Names of paralleling telecom lines:

(b) Length of parallelism:


4. Average value of earth resistivity in the region:

5. Whether LF test necessary:


6. Fault Current & induced voltages etc:


Sl.

No


Name of the Telecom Line/Circuit

Length of Parallelism in Kms

Maximum Fault Current in Amps

Mutual Coupling in Ohms

Net Induced Voltage in Volts

Safe Separating Distance in Metres





















Annexure I

(For Telecom Lines)


  1. (a) Name of the Telecom authority seeking approval:

(b) Reference number & date:

(c) Probable date of energization:


2. (a) Name of the telecom line:

(b) Route map number & date:

(c) Length of telecom line:
3. (a) Names of paralleling power lines:

(b) Length of parallelism:


4. Average value of earth resistivity in the region:
5. Whether LF test necessary:
6. Fault current & induced voltages:


Sl.No.

Name of the Telecom Line/Circuits

Length of Parallelism in Kms.

Mutual Coupling in Ohms

Estimated Fault Current in Amps

Likely Induction in Volts.




















Appendix XII to Chapter 1

(Refer Para 6.6.7)
Comments of Secretary, Central Electricity Board

(Circulated as Annexure VII to Agenda for Central PTCC Meeting

Held at Jaipur on 6th November 1986)
1. Section 32 of the Indian Electricity Act 1910, stipulates that every person generating, transmitting, supplying or using energy shall take all reasonable precautions in constructing, laying down and placing his electric supply lines and other works and in working the system so as not to injuriously affect whether by induction or otherwise the working of any wire or line used for the purpose of telegraphic, telephonic or electric signaling communications or the currents in such wire or line.
The disputes arising out of contravention of the above mentioned provisions contained in Section 32(1) are required to be referred to the Central Government who may direct the owners of the power line to make such alterations and additions which may be necessary for the compliance of these provisions, provided that the telecommunication lines were already in existence prior to the coming of the power lines.
In cases of default in complying with the provisions of this Section, the owners of the power lines shall make full compensation for any loss or damage incurred by reason thereof.
2 Rule 87 of the IE Rules 1956 provides for compliance with the Code of Practice or the guidelines prepared by Power and Telecommunication Co-ordination Committee. It has been further stated that all works to be done by or under Rule 87 shall be carried out to the satisfaction of the Inspector.
Section 47 of the IE Act 1813 provides for punishment for non-compliance with the provisions of Section 32 except where the Court is of the opinion that the case was one of emergency and that the offender complied with the provisions of the Section as far as was reasonable in the circumstances. Similarly, penalty for breach of Rule 87 pertaining to compliance with the regulations of PTCC has been stipulated in Rule 141 of the IE Rules. It may, however, be pointed out that the provisions of Rule 87 of the IE Rules can be relaxed by the State Government or the Central Government as the case may be to such an extent and subject to such conditions as it may think fit.
The above-referred list of power lines erected/energized without PTCC approval includes cases, which are more than 10 years old. No information is available in respect of the following points:


  1. Whether the concerned Electrical Inspector has given approval without ensuring compliance with the provisions of Rule 87;




  1. Whether in any particular case the State Government/Central Government had granted relaxation from the enforcement of the provisions contained in Rule 87;




  1. Whether in each of the cases under reference the telecommunication lines were in existence prior to the coming up of the power lines and the dates of erection of both the power lines as well as telecommunication lines.

After ascertaining in each of the cases that the provisions of Section 32 had not been complied with and for which a reference had not been received from the Telecommunication Department, the Central Government may direct the owner of the power lines to comply with the provisions of Section 32 of the IE Act read with Rule 87 of the Indian Electricity Rules.


Launching of prosecution against the defaulting persons can also be taken recourse to, if considered necessary.
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