Distrubution Lines and Substation Equipment Maintenance and Testing Procedure

Fig-Distribution Lines and Substations Equipment

Maintenance and Testing of Electrical Distribution Lines and Substations Equipment

This article contents as per Bangladesh Electric distribution codes that follow in electrical energy distribution lines and substation equipment maintenance and preventive maintenance works.

The level of performance of all line and substation equipment shall meet the standards of performance for the Distribution Licensee specified by the Commission.

Construction & Maintenance Practices

All electric supply lines and apparatus shall be of sufficient ratings for power,

insulation and estimated fault current and of sufficient mechanical strength, for the duty which may be required to perform under the environmental conditions of

installation, and shall be constructed, installed, protected, worked, and maintained in such a manner as to ensure the safety of human beings, animals, and property.

The relevant code of practice of the Bangladesh Standard and Testing Institution

(BSTI) including National Electrical Code if any may be followed. The material and apparatus used shall conform to the relevant specification of BSTI where such specifications have been already laid.

The Licensee, if already not have, shall prepare and observe the Construction &

Maintenance Manuals for various equipment/ works like 33 kV Lines, 11 kV Lines, LT Lines, 33 kV substations, 11 kV Pole Mounted and other types of substations.

The Construction & Maintenance Manual shall be prepared to take into consideration the following:

(a) Technical Standards for the construction of electrical plants, electric lines and

connectivity to the grid specified by the Commission;

(b) Safety requirements for construction, operation, and maintenance of electrical plants and electric lines specified by the Commission and/or competent authority;

(c) Construction Standards and Standard design layouts of the Licensee;

(d) Institution of Engineers, Bangladesh (IEB) Publications on Code of

Practices, if any;

(e) Code of Practices issued by a competent authority including BSTI for

various equipment and maintenance practices; and

(f) Instruction Manuals for installation, operation, and maintenance issued by

standard equipment by the manufacturer concerned.

The standard tables for conductor size, fuse size, wire gauge, electrical clearance, ground wire size, insulation resistance and earth resistively, etc. shall be included in the Construction and Maintenance manual. The distribution Licensee shall ensure that its construction and maintenance staff strictly observe these Manuals. A copy of the Construction & Maintenance Manual shall be furnished to the Commission.

Preventive Maintenance Schedule and Inspection Manual:

The Distribution Licensee shall prepare a Preventative Maintenance Schedule and Inspection manual for various line and substation equipment installed in the distribution system. The Preventive Maintenance Schedule and Inspection Manual shall include the following important equipment:

a) Power Transformers and Distribution Transformers installed indoors;

b) Power Transformers and Distribution Transformers outdoor installed;

c) Pole Mounted Distribution Transformers;

d) 11 kV & 33 kV Circuit Breakers;

e) 11 kV & 33 kV Overhead Lines including Gang Operated Switches & Drop

Out Fuses;

f) 11 kV & 33 kV Overhead Lines including Gang Operated Switches & Drop

Out Fuses;

g) 11 kV & 33 kV Cable & Cable Boxes;

h) LT Lines; and

Service Connection.

The Preventive Maintenance Schedule and Inspection Manual shall have sections

covering the following:

(a) Recommended Schedule for inspection;

(b) Recommended Schedule for preventive maintenance; and

(c) Recommended Schedule for overhaul.

The inspection schedule and preventive maintenance schedule shall have daily,

weekly, monthly quarterly, and annual periodic activity to be carried out for various equipment.

Maintenance Record:

The Distribution Licensee shall maintain records of periodic inspections carried out in the standard formats prescribed in the Preventive Maintenance Schedule and

Inspection Manual. Records shall be maintained in respect of the following amongst

others:

(a) Power Transformers and Large Distribution Transformers installed indoors;

(b) Pole Mounted Distribution Transformers;

(c) 11 kV & 33 kV Circuit Breakers;

(d) 33 kV and 11 kV Lines.

Regular testing of all the equipment such as transformers, switchgear, protective relays, etc., should be carried out as recommended by the manufacturer and the relevant code of practice issued by the competent authority. 

These shall be carried out at the prescribed intervals and the test results shall be recorded in the maintenance registers. Wherever the test results indicate a decline in the insulation resistance and/or deterioration of the equipment, preventive maintenance shall be carried out to ensure serviceability, safety, and efficiency.

The Distribution Licensee shall maintain well-trained hot-line personnel and all the required tools in good condition and conduct maintenance work by using the hot-line technique, wherever possible, to reduce the period of interruption.

The consumers shall maintain their apparatus and power lines at all times conforming to the Electricity Rules, 1937 and these shall be suitable for connection to the distribution system in a safe and reliable manner.