Indicator Lamps 

Indicating Lamps Selection Procedure for Electrical Distribution and Controlling Panel

Indicating lamps directly not affect electrical distribution network, means power not go breakdown; but it make sure the status of the electrical circuit or a part of that. Sometime it becomes prime issue for safety-induction.

What Should Become in Consideration to Select Indicator Lamps

First of all lifetime of indication lamps is an important issue to select lamps, not because of saving price but because of avoid hassle to replace dead lamp by new one.
So, it is expected, all new indicators should have a minimum continuous burning guaranteed life of 10,000 hours, at their rated voltage.
Indicators should be of the filament lamp, LED or neon type indicator lamps also may use, depends on user choice. It might considerable to LED indicators, should operate at not less than 20mA and red LED indicators should be of the high brightness types.
Indicator lamps placement should be easily replaceable from the front of the panel and be adequately ventilated.
The lamps should be clear and should fit into a standard form of lamp holder. The rated lamp voltage should be ten percent in excess of the auxiliary supply voltage, whether AC or DC. Alternatively, low voltage lamps with series resistors will be acceptable; however resistors should be dimensioned to avoid damage due to heat.

Indicator Lamps Colour Selection

To visualize indicator lamps properly is very important, less glowing or colour merging with vicinity may confuse to identify the status of electrical operation. Significantly colour selection of indicator lamps should comply the standard.
The lamp glasses should comply with BS 1376 and BS 4099 or equivalent National Standard and should be in standard colours, Red, Green, Blue, White and Amber.
The colour should be in the glass and not an applied coating and the different coloured glasses should not be interchangeable.
Transparent synthetic materials may be used instead of glass, provided such materials have fast colours and are completely suitable for use in tropical climates.


Indicator Lamps Energized Voltage

The prime purpose to presence of indicator on electrical panel to visualize presentation of electricity presence or absence. So, it must not be indicator lamp energized by same energy source.
Normally energized indicating lamps be energized from the station Low Voltage AC supply.
Lamps and relays incorporated in alarm fascia equipment should be arranged for normal operation from the station battery, subject to the approval of the Engineer.
Lamp test facilities should be available so that all lamps on one panel can be tested simultaneously by operation of a common push-button. Where alarm facias are specified, all alarm and monitoring indications should be incorporated in the facia.

Where specified every circuit breaker panel should be equipped with one red and one green indicator lamp, indicating respectively circuit closed and circuit open and an amber lamp for indicating auto-trip.
Where specified in the lines of mimic diagrams, indicating lamps may be of the three-lamp single-aspect type.
All lamps should be renewable from the front of panels without the use of special tools.
The variety of indicating lamps provided should be rationalized to reduce maintenance and spares requirements.

Story of Ancient Electricity

Bagdad Battery
The ancient battery in the Baghdad Museum

Ancient Electricity Generation and Using Procedure

Herein this article will try the understand the history of first electricity evaluation and ancient electricity generation procedure and the uses of electricity. We also introduce our-self to Bagdad Battery.

History of Electricity

In 600 BC Thales of Miletus (a Greek colony on the west coast of present day Turkey) writes about amber (elektron in Greek) with cat fur and picks up bits of feathers, becoming charged by rubbing - he was describing what we now call static electricity.

There is a tale, in 900 BC Magnus, a Greek shepherd, walks across a field of black stones which pull the iron nails out of his sandals and the iron tip from his shepherd's stuff. This region becomes known as Magnesia.


Baghdad battery

Some says electricity was originally generated and widely utilized in ancient Egypt, the Baghdad battery and the first arc lights were used at that time.

In 1936, during excavating wreck of a 2000-year-old village Khuyut Rabbou'a, near Baghdad in Iraq, archeologist workers found some extraordinary normal bottle type yellow clay vase. 

They got enough evidence to prove that this vase was used as electricity stuff, this is they called as Baghdad Battery, sometimes referred to as Parthian Battery.

In 1940, Wilhelm Konig, the German director of the National Museum of Iraq, published a paper wondering that Baghdad Battery may have been galvanic cells, perhaps gold used for electroplating onto silver. 

It helps Mr. Konig came to this conclusion because another vases which excavated from Sumerian sites in southern Iraq, were lightly tapped on it and a blue patina or film separated from the surface, which is like silver electroplated onto copper base. Mr. Konig’s this philosophy is a hypothetical understanding to the possibility of ancient electricity generation.

In latter, based on the Mr. Konig’s hypothesis some scientists make replica of Baghdad Battery and produce some electricity which prove his theory. 


The Store

The Site Materials Storage Protection and Handling Procedure

The service-provider should be responsible for providing his own storage area for the storage and protection against loss, theft or damage of plant, equipment and materials during the execution of the contract and until handover the plant.

The Service-provider should be responsible for the off-loading, transport and all handling of plant etc., supplied by him or his sub-service-providers.

The handling and storage of any plant at the site are to be at the risk and responsibility of the Service-provider and will not be the responsibility of the Employer. Watchmen should be provided by the Service-provider on own responsibility.

The Service-provider is to arrange for the protection of all material against corrosion and mechanical damage during storage and erection at the site, to the satisfaction of the Employer.

What Facilities Should be Provide at Site-store

The Service-provider should provide lockable cabinets in each of the individual substations, which are to contain the following:

v One set of paper prints of the complete record drawings for the section of the work. These should be arranged in a logical sequence in accordance with the drawing list contained in the O&M manuals. Record drawings are to be grouped into labeled pockets or binders to minimize disturbance in locating specific drawings. As-built drawings are to be stored in these locations prior to the issue of record drawings.

v Two complete sets of O&M manuals

v Volumes of factory and site test reports/certificates

v Copies of maintenance log sheets, record sheets etc.
v Space for stationery an operators’ log books

These cabinets should match other furnishings being provided in the substation and the location as such items is to be included in the design of the substation layout.



General Packing and Marking Specification for Engineering Plant and Equipment Shipment

Packing and MarkingThe purpose of this article to provide the general packing and marking specification and guideline to the suppliers, employers, vendors, transportation and erection contractor for an engineering plant and equipment shipment in an electrical power transmission line underground cable installation project under turnkey basis. The service-provider or the main contractor is the responsible to shift and transport the equipment and plant from abroad and within the employer country following the all rules and regulations.

This specification or guideline is the minimum requirements, the service-provider or vendor will ensure by his own experience using the nature of plant item and exact requirements in destination.

Packing and Marking Method

Each item is to be export packed and properly protected for shipment, transport and storage in the port area and for transport to and storage on Site.

All Plant provided under this contract shall have the packing marked in the following manner.

A green band shall be painted all around each package. The band shall be 8” wide or ¼ of the length of the packing whichever is the less. Each package should have the following information printed on it in bold letters:-

Port of Loading;
Name of Consignee;
Purchase Order Number;
Brief description of Stores;
Number of Package;
Gross, tare and net weight;
Contractors Name;
Contract Title;
Contract Number;
Port of Landing.

All members comprising multipart assembles, e.g. steel frameworks, are to be marked with distinguishing numbers and/or letters corresponding to those of the approved drawings or materials lists.

Colour banding and approved code is to be employed to identify members of similar shape or type but of differing strengths or grades.

Cases containing delicate items such as relays and instruments should carry a separate marking.

Sensitive equipment packages shall be opened in the presence of a representative of the Employer.


Handover a Project
Fig- EHV-HV Electrical Substation

The Handover-Takeover Procedure after Achievement a Turnkey Project 

The article furnished to prepare a project for final tusk just turn the key from service-provider to employer, after completion the all work to able the plant run successfully. Here denoted the procedure- commissioning the plant after finishing all physical works, the guideline for responsibility of any defect after handing over the plant and final acceptance procedure of the project.

Plant Taking Over Conditions after Completion the Work

After satisfactory completion of the tests on commissioning, the Engineer will issue a taking over certificate for the plant. 

The issue of any such certificate shall not however relieve the Service-provider of any of his responsibilities in respect of proving that the performance of the plant meets the guaranteed values.
The Taking over certificate shall make reference to a schedule of outstanding minor defects and omissions which have been accepted by the Engineer as not affecting the full and safe operation of the plant. 

The Service-provider shall rectify such defects and omissions not later than 3 months after taking over.
The date certified in the taking over certificate shall be the date on which the tests on completion were completed.


Responsibility for Defect after Taking over the Plant

Accordance with the General Conditions of Contract, the service-provider shall be responsible for making good defects or damage which may appear or occur during a 12 month guarantee period from the date certified in the Taking over Certificate.
Following any remedial work or replacement of any component part during the 12 months, the guarantee period for such a part shall be extended, commencing from the date at which the remedial work was completed.
Immediately prior to the completion of this period the Employer reserves the right to request the Service-provider to open up for inspection the whole or any part of the Plant. 

The Employer will provide the labour to works under the direct supervision of the Service-provider’s representative for the purpose of such inspection.
The Service-provider shall submit for approval the arrangements he intends making under this contract for the making good of defects and for providing the supervisory service detailed above.


Spare Parts
Fig- Fuse

The Spare Parts Provision and Condition Included as Obligation for service-provider

The Service-provider is to propose comprehensive schedules of spare parts requirement for 5 years service of the Plant.

Those Spare Parts required for routine maintenance are to be provided under the contract agreement.

The Service-provider should provide detailed schedules of those emergency spares he considers that it would be prudent for the Employer to purchase in schedule as Recommended Spare Parts.

The Service-provider should guarantee and provide certificate from the manufacturers that spare parts for all plant should be available for a minimum period of 10 years from contract completion.


Spare Parts Delivery and Handover Requirements

The local currency element should include all handling, local transport and delivery to a store or stores nominated by the Employer. Spares should be handed over to the Employer as soon as they arrive on site, and should be checked in the presence of the Employer’s representative. The Service-provider should obtain a receipt for the material at the time of delivery to the Employer’s stores.

Any spare material so ordered should be strictly interchangeable with the parts which it is intended to replace, packed and treated in such a manner as to be suitable for storage in the climate at the site for an indefinite period and each part should be clearly marked for identification purposes, outside the package where applicable.

Schedules of spare materials in triplicate should be handed over to the Employer arranged for the easy identification and checking of materials at the time of hand over. Prior to the handing over date for Service-provider spares, the Service-provider should be responsible for all security arrangements and the safe custody of the spare materials.

In addition to the contract spares listed the Service-provider should ensure that sufficient stocks of commissioning spares are available on site to enable the rapid correction of any defect discovered during site testing.


Commissioning Spare Parts Obligations

The provision of commissioning spares is the Service-providers responsibility and the cost of these is to be borne by the Service-provider. Contract spares are not be utilized as commissioning spares.

The Service-provider should submit to the employer’s representative, on a monthly basis, a complete schedule of the stock of commissioning spares available on site. In addition the service-provider should provide a monthly return on all items which have required replacement from the commissioning spares stock. The Employer or his representative may require the service-provider to return any item of defective plant to the manufacturer for a report on the cause of failure.

Current Ratings Correction Factors on Cable Laying Conditions

XLPE Insulated Copper Conductor Power Cable
Fig- Crossectional View of XLPE Power Cable

Continuous Current Ratings Correction Factor Varies on Different Cable Laying Conditions

Today we will try to find how various laying conditions of cable become a factor for current ratings of XLPE insulated copper conductor power cables, means depends on cable laying various condition current carrying capacity increase or decrease. Such as various ambient air temperatures, various ground temperatures, various thermal resistivity of ground and various depth of cable laying is the factor for cable current ratings. 

In our previous post Continuous Current Ratings of XLPE Insulated Power Cable we try to find the current carrying capacity for various sheathed like Aluminium, Lead or Copper wire shield XLPE insulated copper cable.

To determine current capacity for the various laying conditions than those indicated on the every table, multiply table values by the correction factors shown below.

Correction Factors for Various Ambient Air Temperatures
Air Temperature(oC)
20 oC
25 oC
30 oC
35 oC
40 oC
45 oC
50 oC
Rating Factors
Air Temperature(oC)
15 oC
20 oC
25 oC
30 oC
35 oC
40 oC
45 oC
Rating Factors
Thermal Resistivity of Soil (oCm/w)
Rating Factors

Correction Factors for Various Ground Temperature Correction Factors for Various Thermal Resistivity of Ground
Correction Factors for Various Depth of Laying


Depth of Laying (m)

Rating Factor

0.50 ~ 0.70


0.71 ~ 0.90


0.91 ~ 1.10


1.11 ~ 1.30


1.31 ~ 1.50



Insulative Materials

A Guide to Use Electrical Insulation Materials and Insulating Oil

Insulating materials should be suitably ended so as to prevent deterioration of their qualities under the specified working conditions. Account should be taken of international standard the IEC 85 and IEC 505 recommendations.

Ebonite, synthetic resin-bonded laminated material and bituminized asbestos cement-bonded panels should be of suitable quality selected from the grades or types in the appropriate British Standard, IEC Standard, or approved National Standard.

All cut or machined surfaces and edges of resin-bonded laminated materials should be cleaned and then sealed with an approved varnish as soon as possible after cutting.

Linseed oil and untreated materials of fiber, leatheroid, presspahn, asbestos or other similar hygroscope types of materials should not be used for insulation purposes. Untreated leatheroid and presspahn may be used for mechanical protection of winding insulation.

Wherever practicable, instrument, apparatus and machine coil windings, including wire wound resistors, with the exception of those immersed in oil or compound, should be thoroughly dried in a vacuum or by other approved means and should then be insulating varnish. Varnish with a linseed oil base should not be used.

No material of a hygroscope nature should be used for covering coils. Where inter-leaving between windings in coils is necessary, only the best Manila paper, thoroughly dried, which permits penetration by the insulating varnish or wax, should be used.

The List of Insulating Materials 

The insulating materials list may become very big, we can summarize as below:



How Comply the Insulating Oil (Transformer Oil) Requirements

This is denoting the requirements of insulating or transformer oil for a new project when supplying or installing plant and equipment rather than an operating an existing one.

Insulating oil should comply with the requirements of International Standard IEC 296. Insulating oil should be provided by the service provider for all oil-filled apparatus and 10% excess should be provided for topping up purposes in sealed drums. 

The service provider should satisfy himself that suitable oil treatment facilities are available at site for his use. If the service provider is unable to obtain written assurances to this effect he should provide such oil treatment facilities as required to meet the specification of the agreement.

How Effect Moisture on Transformer Oil Breakdown Voltage

The main purpose to use insulating transformer oil as a heat transfer and a good dielectric material. The insulating oil can act as an insulator up to a certain level of voltage. The voltage at which level fail to insulate is known as breakdown voltage.

The level of breakdown voltage depends on important factor of moisture particle into the oil like others factors such acidity, foreign particle, pressure etc. Effect of Moisture on Breakdown Voltage

The percentage of breakdown voltage relative to dry oil decrease as increase the percentage of relative moisture level. The typical sample graph shows the relationship between breakdown voltage and moisture saturation. This test must comply with the International Standard IEC 60156.

Short Guide to Transformer Oil Analysis

Moisture ingress into transformer oil is a big factor, along with others various factor it also cause of transformer breakdown; so keep the transformer on smooth operation, regular observation and test is required. The details test and observation for transformer oil should consider the points as below:

·        Appearance
·        Color
·        Corrosive Sulphur
·        Dielectric Strength
·        Density
·        Dielectric breakdown voltage
·        Dissolved gas analysis
·        Furfural and related compounds
·        Interfacial tension (IFN)
·        IFT-NN Relationship
·        Kinematic viscosity
·        Neutralization Number (NN)
·        Oxidation Stability
·        Sediment, sludge
·        Specific gravity
·        Suspended particles in oil, visual
·        Trace analysis
·        Water content
·        Additional expertise

How Comments on Oil Classifications

How say the transformer oil is good, bad or very bad; here in some features are given below that will help to comments on transformer oil good or bad.

Good Oils
 NN 0.00 - 0.10
 IFT 30.0 - 45.0
 Colour Pale Yellow
 OQIN 300-1500

  Proposition A Oils
 NN 0.05 - 0.10
 IFT 27.1 - 29.9
 Colour Yellow
 OQIN 271 – 600
Marginal Oils
 NN 0.11 - 0.15
 IFT 24.0 - 27.0
 Colour Bright Yellow
 OQIN 160 - 318
Bad Oils
 NN 0.16 - 0.40
 IFT 18.0 - 23.9
 Colour Amber
 OQIN 45 – 159

Very Bad Oils
 NN 0.41 - 0.65
 IFT 14.0 - 17.9
 Colour Brown
 OQIN 22 - 44
Extremely Bad Oils
 NN 0.66 - 1.50
 IFT 9.0 - 13.9
 Colour Dark Brown
 OQIN 6 - 21

Where, OQIN = IFT/NN