What Happen If Cables Placed In Magnetic Metal Conduit

What Happens If Cables 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  

Sponsored:

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.

ALARM EQUIPMENT DETAILS FOR HV & EHV POWER TRANSMISSION SYSTEM

Fig: Fire drill in an airport

Alarm Equipment Associate with Power Control Panel in 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.

Multiple Alarm Tone

Where it is necessary to differentiate between the urgency of alarms then various approved alarm tone devices should be provided in this Contract. In addition and where specified an alarm beacon to the approval of the Engineer should be provided.

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.

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.

Arresters shall be designed and tested in accordance with the requirements of IEC 99 4. Any departure shall be the subject of agreement between the Engineer and the Contractor. Routine tests shall be carried out in accordance with the requirements of Section 15 of this Specification.

Surge arresters shall be housed in porcelain insulators designed to withstand extremes of the environment described. The insulation shall have a minimum creepage distance of 25 mm/kV rated system phase-to-phase voltage. Porcelain shall comply with IEC 233. The method of sealing against the ingress of moisture shall be of a type well proven in service and the manufacturing procedures shall include a practical leak test which can be demonstrated to the inspecting engineer if required.

The internal components of arresters shall be arranged to minimize radial voltage stresses, and internal corona and to ensure minimal capacitive coupling with any conducting layer of pollutant on the outside of the porcelain housing except where approved, organic materials are not permitted.

Good electrical contact shall be maintained between resistor blocks, considering any thermal expansion and contraction of the block or mechanical shock during transport and erection, by installing a well-proven clamping system.

Metal oxide arresters installed outdoors shall be able to dissipate when new, twice the energy generated in the resistor blocks when energized at their maximum continuous operating voltage immediately having been subjected to the discharge duties specified in IEC 99 4 and assuming that the porcelain housing and the surrounding air is at least 5˚C higher than the maximum ambient air temperature specified.

Good quality control of the manufacturing process of the resistors shall be ensured by rigorous testing procedures. The procedures shall ensure that the characteristics of the blocks are, and will remain, within the specified limits when new and throughout the anticipated life of the arresters. Samples may be selected at random by the Engineer for special tests to be agreed upon with the manufacturer.

All surge arresters shall be fitted with a pressure relief diaphragm which shall prevent explosive shattering of the porcelain housing in the event of an arrester failure and the arrester shall have been tested according to the high and low current tests specified in IEC 99 1.

Arresters shall be supplied completely for installation in an outdoor switchyard, including supporting structures, insulating bases, and surge counters, one per phase, and, if applicable, grading rings. The material used for terminals shall be compatible with that of the conductors to which they are to be connected.

Each arrester shall be identified by a rating plate in accordance with the requirements of IEC 99 4. In addition, an identification mark shall be permanently inscribed on each separately housed unit of a multi-unit arrester so that units can be replaced in the correct position in the event of them being dismantled.

Surge counters shall have an internal assembly that is matched to the line discharge capability of the arrester and shall include a leakage current meter with a bilinear scale for ease of reading. Auxiliary contacts are to be provided to signal remote indications of the counter operation.

Sponsored:

Technical Data Schedule for 132 kV and 33 Surge Arrester

Sl. No.	Item no.	Unit	Nominal System Voltage
			132 kV	33 kV
1.	Manufacturer
2.	Model Number
3.	Type:
4.	Continuous operating voltage	kV RMS
5.	Rated voltage	kV RMS
6.	Standard nominal discharge current	kV
7.	Reference current at ambient temperature	mA
8.	Reference voltage for above	kV RMS
9.	Steep current impulse residual voltage	kV pk
10.	Lightning impulse residual voltage at
	5 kA	kV pk
	10 kA	kV pk
	20 kA	kV pk
11.	Duty Class
12.	Discharge Class
13.	Pressure relief class
14.	Nominal Diameter of resistor blocks	mm
15.	Number of resistor blocks connected electrically in parallel
16.	Number of separately housed units pre-phase
17.	Overall height of arrester (without supporting structure)	m
18.	Overall height of arrester including grading ring if applicable	mm
19.	Clearances:
	Phase to earth (from center line)	mm
	Phase to phase (center line to center line)	mm
20.	Overall height of arrester (without supporting structure)	kg
21.	Maximum cantilever strength	Nm
22.	Maximum force due to the wind (at maximum specified gust speed)	Nm
23.	Minimum creepage distance over the insulator	mm

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?

Sponsored:

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

Sponsored:

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.