Electrical Power Cable Is an Electrical Transformer

An Electrical Power Cable Is an Electrical Transformer

How does an electrical power cable work as an electrical power transformer? It may be your question. It’s true that we know electrical power cable works as a capacitor, because the condition to be a capacitor, two metallic components need to be placed in parallel. 

SURGE ARRESTERS SPECIFICATION FOR 132 KV & 33 KV LINE

Surge Arrester Specification

Surge Arrester Requirements for 132kV and 33kV Underground Cable Line Projects

 

Surge arresters shall be of the type employing non-linear metal oxide resistors without spark gaps. The Contractor shall demonstrate by calculations that the surge arresters will adequately protect the switchgear arrangement proposed.

JACK AND PLUG CONFIGURATION IN DIFFERENT COUNTRIES

Fig-Plug and Socket Types

Jack & Plug or Plug & Socket Configuration in Various Countries

There is no guy who hasn’t faced fixing an unmatched Plug & Socket or Jack & Plug, ever, you say. Especially you, who frequently visit different locations or live in an Asian country where not follow any specific standard, often face this problem when using a computer/laptop, mobile, etc., charger.

Alarm Equipment Details for HV & EHV Power Transmission System

Fig: Fire drill in an airport

Alarm Equipment Associate with the Power Control Panel in the Transmission Grid Station

Where an alarm system is specified in this article, especially for high-voltage transmission grid and normal Voltage Distribution substation, it should consist of an initiating device, a display unit, and push buttons mounted on the front of the appropriate control panel, together with a continuously rated audible warning device, flasher unit, and relays. The relays should, wherever possible, be mounted inside the same panel; where the number of alarms to be displayed makes this impracticable, a separate alarm relay cubicle or cubicles will be considered as an alternative.

Conductor Stranding Perspective of Power Cable Construction

Conductor Stranding Perspective of Power Cable Construction

Conductor stranding is a major aspect of cable construction that came long experience in different circumstances. 

The problem with larger sizes of solid conductors is too rigid for installation in curvy areas, jointing, and termination work. The solution to these difficulties comes from conductor stranding. 

The procedure of stranding is used depending on the metal temper and types. In general Copper conductor and Aluminum, copper conductors and aluminum conductors are used for power cable construction. Normally Aluminum is softer than Copper, so the use limit is higher than that of copper.

Fig: Conductor strands arrangement system

Switching and Earthing Operating Procedure

Switching and Earthing Operative Procedure in Electrical Energy Network

 

The keywords of this article are Switching & Earthing; we are not going to learn technical details about switching and earthing procedures in this piece, but we would like to keep in limit our focus on the key points for the safe operation of the switching & earthing system.

What Happen If Cables Placed In Magnetic Metal Conduit

What Happens If Cables are Placed In Magnetic Metal Conduits 

Do we know what happens if cables are in a magnetic metal conduit? Yes, at least we know that in any circumstances, the individual phase of an AC (alternating current) circuit is in a separate magnetic metal conduit. 

ARMOUR EARTHING ASSEMBLING FOR SINGLE CORE CABLE

Armour Earthing Assembly for Wire Armour Single Core Cable

33kV Cable Earthing System

Cable armour earthing is important for medium voltage (MV), high voltage (HV) and extra high voltage (EHV) system. 

Our discussion on this article is limited only single core plastic or paper cable wired armour earthing procedure for medium voltage (MV) system or 7.2 kV to 36 kV ranges.

The crystal clear step-by-step assembly figure shown the complete procedure of earthing system for wired armour cable.

If you follow the shown 9 step carefully, we hope you will be able to assemble the cable armour earthing successfully.

9 Step to Earth Cable Armour  

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1. First of all remove the over-sheath according to the dimension given the appropriate manufacturer Installation Instruction, Remove the armour according to dimension as per shown in the drawing. Clean the end of the over-sheath for a length of 250 mm.
2. Then slide the outer sleeve over the cable, and disassemble the clamping rings. Slide one clamping ring lug-downwards over the cable as shown in the figure 2.
3. Following the figure no-3 spread the armour wires as shown in the drawing and screw the other clamping ring loosely to the lugged clamping ring.
4. Install the termination in accordance with the Installation Instruction of termination manufacturer. Pass the end of the earth lead down through the clamping rings and connect it to one lug of the clamping ring. Tighten the clamping rings, refer to figure no-4.
5. With a small overlap and slight tension wrap two layers of sealant tape round the overs-heath for a length of 50 mm, just below the armour wire ends. Wrap two layers of sealant tape round the earth conductor so that it will be just below the armour wire ends. Attach the earth conductor to the other lug of the clamping ring as figure-5.
6. As shown in figure-6, bend the armour wires back and bind the ends to the over-sheath with a wire binder or plastic tape. noted that all sharp wire ends must be covered with plastic tape.
7. With a slight tension and small overlap wrap two layers of sealant tape over the lower end of the termination for a length of 50 mm.
8. Position the top end of the outer sleeve level with the top of the sealant tape. Shrink it into place starting at the center. Shrink the lower end first and work towards the upper end.
9. Yes, you have done; installation of earthing assembly for armour is completed.

This is the basic instruction for cable armour earthing, to do it physically you must follow the manufacturer installation instruction and necessary safety code. If it is helpful, then share with others to help them. 

What Is the Voltage Classification?

Nominal Voltage Classification in Transmission and Distribution System

To identify the voltage level effortlessly in a transmission and distribution system a significant voltage classification is essential. The voltage class is used not only to identify the level of system voltage, but the main importance is to classify the Apparatus voltage ranges for the operation and maintenance of an electrical energy transmission and distribution system.

Why Does Single-Phase Require a Neutral Conductor but not in Three-Phase?

Do you think about why single-phase electricity requires a neutral conductor while three-phase electricity does not?

In a single-phase electrical system, power is transmitted using two conductors: the live conductor (carrying current) and the neutral conductor (completing the circuit). The neutral conductor is necessary to complete the circuit and provide a return path for the current back to the source.

MCB: MINIATURE CIRCUIT BREAKER OPERATION BASIC

What is MCB?

MCB is a device designed to protect an electrical circuit's wiring from the serious damage which would be caused if it has to carry a current that is too high for the diameter of its wires.

The MCB or Miniature Circuit Breaker is actually working for both electrical circuits' make or break switch and protection device fuse.

Likely normal fan/light switches, MCB also can operate manually as circuit ON or OFF; its specialty is, it can break the circuit automatically to protect from overcurrent.

Fuse is the very first protection device for an electrical circuit. A fuse is actually nothing but a thin wire that is enclosed in a protective casing and plugged into the circuit.

Emergency Restoration System for EHV & HV Power Transmission

ERS is short for Emergency Restoration System, well known to the line crew of national grid, and utility companies, and associated with other power transmission and distribution companies. ERS structures are designed for quick bypassing and restoring the transmission line in an emergency.

Why ERS Structure Is Required?

ERS Tower

Damage or breakdown is always unplanned. So, always a pre-planned is necessary to overcome the breakdown within the shortest time. ERS structure is pre-fabricated for quickly and safely bypassing damaged permanent structures; also ERS structures allow us to rebuild or replace the permanent structures with minimum time constraints.

What Is Terrain ERS Tower?

The same ERS tower is not effectively used everywhere in the glove due to the geographical diversity in the world. So, ERS tower or ERS structure types are mainly considered:

       I.          support mountain-to-mountain span;

      II.          crossing the hot and hard-packed sands in the desert area;

         III.          Soft-soiled flood plains territory.

What Specification Should Consider for ERS Tower?

The following specification should be considered for selecting an emergency restoration system (ERS) tower:

                           i.          the column sections' workability of ERS;

                         ii.          the foundations for erection ERS;

                       iii.          the articulating gimbal joint of ERS tower;

                       iv.          the guy wire specification;

                         v.          the guy wire accessories;

                       vi.          the insulators;

                      vii.          the anchors to balance the load;

                    viii.          the guy plates to take sufficient tension;

                       ix.          the conductor hardware;

                         x.          Construction tools;

                       xi.          other spare parts;

                      xii.          computer software and trained personnel.

What Standard Should Follow for ERS Structure?

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ERS structure is principally used in an emergency situation. So, product quality considering safety must be the highest prioritized. Marinating international standard-there is the “IEEE Guide for the Design and Testing of Transmission Modular Restoration Structure Components”, including earlier or later versions. Strict conformance of IEEE 1070-2006 includes testing requirements, material requirements, fabrication requirements, and all other geometric and dimensional requirements listed in the IEEE 1070 standard, without exception.  The manufacturer shall submit with his proposal, a certified copy of the Design Test Report as required in Section 4 of IEEE Standard 1070-2006.

Feature Components of ERS Structure

ERS structure needs to contain the following feature components to make it easy and simplified various configurations to comply with emergency system restoration:

a.     light-weight to allow for manual transportation;

b.    different configurations;

c.     Comply with IEEE Standard 1070-2006, “IEEE Guide for the Design and Testing of Transmission Modular Restoration Structure Components”;

d.    minimizing the number of guy wires used to be;

e.     welding complies with Section 3 of IEEE Standard 1070;

f.      Testing complies with the IEEE Standard 1070-2006 “IEEE Guide for the Design and Testing of Transmission Modular Restoration Structure Components”;

g.     size and diameter of threaded fastener comply with IEEE Standard 1070;

h.    All used ferrous materials must be galvanized complying with standard ASTM A153;

i.       All Column sections must comply with IEEE Standard 1070;    

j.      All column sections must be tested in accordance with Sections 5.1 and 5.2 of IEEE Standard 1070;

k.     All Foundation Plates, Gimbal Joint, Guy Plates, Box Sections, and Insulators must be made in accordance with IEEE Standard 1070.

Listed Tools for Installation ERS Tower

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A number of hydraulic tools and hand tools are required to assemble and erection ERStower:

A.   Anchor Installation Tools

                           i.          gasoline hydraulic power unit;

                         ii.          hydraulic driving hammer;

                       iii.          hydraulic rotary hammer;

                       iv.          hydraulic proof testing unit;

                         v.          hydraulic hoses, rock drill bits, torque installation tools, etc.

B.   Construction Tools

                           i.          snatch blocks and rigging ropes;

                         ii.          A ½ ton hydraulic capstan winch with foot pedals;

                       iii.          high-quality 2-ton Tractel Tirfor-style grip hoists;

                       iv.          reversible ratchet;

                         v.          six (6) to three (3) ton reversible chain hoists;

                       vi.          pulling eyes;

                      vii.          automatic wire grips;

                    viii.          double loop 6x37 steel wire rope slings;

                       ix.          self-contained 6-ton hydraulic wire cutter;

                         x.          foundation stakes;

                       xi.         Aluminium conductor lifting hooks, etc.

Testing and Commissioning:

After installation must carry out the field testing and commission before going to operate. This test may include visual, equipment-oriented, or even software base computerization.

If you think it is helpful then share it with your friends or put your valuable comments to improve this article.

Voltage Drop Calculation for Electrical Power Cable

What is Voltage Drop for Cable?

When current flows in a cable conductor a voltage drop is developed in between the ends of the conductor which is the product of flowing current and the impedance of the cable.

Why Calculation Voltage Drop?

It is a common obligation for the designer to calculate the voltage drop as requirements are the main factor in determining the minimum conductor sizes (cross-sectional area) that can be used for a particular electrical circuit.

How to Calculate Voltage Drop?

Calculating the voltage drop of a circuit the designer has two options to choose of them depending on the project requirements. These pretty two options are as below:

Simple Design Approach

Accurate Design Approach

The simple design approach is a rough estimated one which sometimes leads to the use of larger conductor cross-sectional areas than are necessary for the project. If you consider a simple approach, then basically the following information is needed:

·        

•     Type of cable;
•     Conductor cross-sectional area;
•     Method of installation (for AC circuits only);
•     Circuit route length;
•    Type of circuit (DC, single-phase AC or three-phase  AC);
•     Load on the circuit.

Information is not needed for a simple approach:

•   Type and nominal current rating of the associated overcurrent device;
•   Ambient temperature;
•   Whether the circuit is run singly or grouped with other  circuits;
•    The power factor of the load.

On the other hand, an accurate design approach takes more into consideration conductor operating temperature. Above mentioned four “not needed information” for a simple approach should consider for a more accurate approach, especially two factors namely:

•    The ambient temperature
•    Whether the circuit is to be run singly or grouped with other circuits.

Calculate Voltage Drop Smartly:

We who work with cable system sometimes have to calculate voltage drop in short and very smartly. Considering this point of view following two formulas may be helpful for voltage drop calculation smartly.

Voltage Drop Calculation Formula for Single Phase Circuit:

V_d=2Il (R cos ø + X sin ø)  V

Voltage Drop Calculation Formula for Three Phase Circuit:

V_d=√ 3 I l (R cos ø + X sin ø)  V

Where

V_d = Voltage drop in Volt;

I = Load current in Amper;

R =A C Resistance in Ω/km;

X =Reactance in Ω/km;

cos ø = Power factor;

l  = Length in km;

X = ^ωL10-3

 ^ω=2 π f

L = from table mh/km

The limit of voltage drop depends on national code and standards which vary from country to country, and hope we got some basic idea on Voltage Drop for Electrical Power Cable.

ELECTRICAL PANEL WIRING AND TERMINAL BOARDS CONNECTION PROCEDURE

Guide to Electrical Control Panel Wiring and Terminal Board Connection Procedure

This document provides a guide for the service provider on a high voltage and medium voltage transmission line power project from the employer site to ensure that all electrical equipment mounted in switch-gear, panels, kiosks, and desks, etc. must have readily accessible connections and be wired to terminal blocks for the reception of external cabling.

Of course, all wiring be situated of adequate cross-sectional area to carry prospective short-circuit currents without any risk of damage to conductors, insulation or joints.

Important to consider that selecting the wrong wire types may cause operational problems and could render the unsafe for human and equipment. Some of the important factor of such as:

·        Size of the conductor;

·        Insulation of material;

·        Made of;

·        Whether Solid, standard or flexible etc.

Panel Wiring Cable Selection Guide

All cable for panel wiring should be of type CR or CK to BS 6231 unless the design of the plant requires the cabling to withstand more onerous operating conditions in which case cabling should be suitable for these conditions.

The minimum cross-section of panel wiring cable or wire should be 2.5mm² for all secondary wiring associated with current transformers of the nominal secondary rating of 0.5A or higher.

The size of wiring cable for circuits other than CT (Current Transformer) secondary wiring should not be less than 1.5mm² cross-section.

The minimum strand diameter of copper or tinned copper flexible conductors should be 0.20 mm for flexible cable, the minimum cross-sectional area should ensure 0.5mm² for all control cables.

 The wiring within panels on circuits not directly associated with circuit breaker protection and control, having a continuous or intermittent load current less than 1 amp, the use of smaller line down to 0.25mm² may be permitted subject to Engineer’s Approval.

Where an overall screen is used, this should be a metallic screen or low resistance tape with drain wire as above.

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Control Panel Wiring Procedure

Wiring should be supported using an insulated system which allows easy access for fault finding and facilitates the rapid installation of additional cables.

Small wiring passing between compartments which may be separated for transport should be taken in terminal blocks mounted near the top of each compartment, separately from those for external cable connections.

Terminal Board Connection Procedure

Both ends of every wire should be fitted with ferrules of insulating material complying with BS 3858 or equivalent National Standard and engraved in black. The identification numbering system used for the ferrules should be to the approval of the Engineer.

Where new equipment must interface with existing equipment double ferrule should be employed if the two numbering system is not compatible.

Connections to apparatus mounted on doors, or between points subject to relative movement, should be made in cable type CK to BS 6231, arranged so that they are subjected to torsion rather than bending.