MGM 112 Type 321 3.3kV Unscreened Armoured Mining Power Cable
MGM 112 Type 321 cross-section
  1. MGM 112 Type 321 3.3kV Unscreened Armoured Mining Power Cable
  2. MGM 112 Type 321 cross-section

MGM 112 Type 321 3.3kV Unscreened Armoured Mining Power Cable

MGM 112 Type 321 is a 1900/3300 V unscreened armoured mining power cable: three EPR phase cores and one earth core laid around an elastomeric cradle, tinned Class 5 copper, steel armour and chloroprene sheath, 3×35+25 to 3×120+70 mm².

  • Rated / test voltage1900/3300 V / 7.5 kV
  • Cores × size3×35+25 to 3×120+70 mm²
  • ConductorTinned Cu, IEC 60228 Class 5
  • ScreenNone (phase and earth cores)
  • Lay-upCores on elastomeric cradle
  • Armour / sheathGalv. steel / chloroprene
  • Overall diameter60.3 – 93.7 mm
  • Current rating at 25 °C135 – 295 A

Download MGM 112 Type 321 datasheet (PDF)Full specifications

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Product overview

MGM 112 Type 321 is the unscreened 3.3 kV design of the MGM 112 family: a 1900/3300 V armoured rubber cable with three phase cores and one earth core, none of them screened. It is built to the MGM 112 specification of the Turkish Hard Coal Enterprises MGM mining cable series.

Instead of screens, Type 321 separates the cores mechanically: they are laid around an elastomeric cradle so that no two cores touch. With 3.0 mm EPR phase insulation, a rubber bedding, galvanized steel pliable armour and a heavy-duty chloroprene sheath, it supplies excavating and crushing machines in deep mines where explosive gases and dust can accumulate, and on surface.

Browse the MGM mining cable category for the other cables in the Turkish hard coal MGM series or download the MGM 112 Type 321 datasheet (PDF).

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Application & Features

Selection overview

Type 321 carries 3.3 kV power to the same class of equipment as its screened sibling: longwall face equipment, crushers, roadheaders and continuous miners, pumps and conveyor drives, and the section substations that feed them. It is chosen where the mine's 3.3 kV protection works with the earth core and armour and does not call for a screen on each phase, for example on semi-permanent feeders along a gate road or supply cables to plant that is moved only between panels.

The elastomeric cradle keeps a fixed spacing between the cores, so the phase insulation is not pressed against the neighbouring core when the armoured cable is bent or crushed. The galvanized steel pliable armour and chloroprene sheath take the mechanical abuse. If your protection scheme requires individually screened phase cores, specify the MGM 112 Type 331 instead.

  • 3.3 kV mine distributionSupplies face equipment, crushers, conveyors and section substations at 1900/3300 V, underground or on surface.
  • Cradle-separated coresPhase and earth cores laid around an elastomeric cradle without touching each other.
  • Unscreened 3+1 layoutNo phase screens; a full insulated earth core from 1×25 to 1×70 mm² carries protective current.
  • Armoured and chloroprene sheathedGalvanized steel pliable armour under a heavy-duty chloroprene sheath; mine approval quoted per order.
Row of hydraulic roof-support shields and a shearer at a longwall face in the Deutsches Bergbau-Museum, the kind of 3.3 kV face equipment an MGM 112 Type 321 cable supplies
Longwall face with hydraulic roof-support shields and a shearer. Face equipment like this is fed at 3.3 kV through armoured cables such as MGM 112 Type 321. Photo: Till Niermann, CC BY-SA 3.0, via Wikimedia Commons.

Specifications

Technical data

Values from the current TEBAOFLEX MGM 112 Type 321 datasheet. The final construction is confirmed on the approved datasheet for your order.

Electrical, mechanical and material data

Parameter Value
Rated voltage 1900/3300 V
Test voltage 7.5 kV
Conductor Stranded, tinned copper wire, IEC 60228 Class 5
Insulation EPR
Phase cores Unscreened
Earth core Unscreened
Lay-up Cores laid around an elastomeric cradle without contact
Bedding Rubber-based bedding compound
Armour Galvanized steel pliable armour
Outer sheath Heavy-duty chloroprene compound
Design specification MGM 112
Application Power supply for excavating and crushing machines and equipment; deep mines where explosive gases and dust can accumulate, and surface use

MGM 112 Type 321 dimensions, weights and electrical data

Cable type Unit 3×35+25 3×50+25 3×50+35 3×70+50 3×95+70 3×120+70
Phase cores / cross-section mm² 3×35 3×50 3×50 3×70 3×95 3×120
Phase stranding mm 276/0.40 396/0.40 396/0.40 360/0.50 475/0.50 608/0.50
Phase conductor diameter mm 8.40 10.10 10.10 11.90 13.90 15.50
Phase insulation thickness mm 3.0 3.0 3.0 3.0 3.0 3.0
Earth core / cross-section mm² 1×25 1×25 1×35 1×50 1×70 1×70
Earth stranding mm 196/0.40 196/0.40 276/0.40 396/0.40 360/0.50 360/0.50
Earth conductor diameter mm 6.75 6.75 8.00 9.75 11.90 11.90
Earth insulation thickness mm 3.8 5.0 4.4 4.5 4.6 4.9
Radial inner sheath mm 2.5 3.8 3.8 3.8 5.0 5.0
Min. inner sheath diameter mm 44.3 51.3 51.3 56.4 63.8 67.5
Max. inner sheath diameter mm 46.8 53.3 53.3 59.4 66.8 71.3
Size of armour mm 7/0.90 7/0.90 7/0.90 7/0.90 7/1.25 7/1.25
Radial outer sheath mm 5.3 5.4 5.4 6.3 6.8 7.2
Min. overall diameter mm 60.3 66.9 66.9 74.4 84.9 89.4
Max. overall diameter mm 64.1 70.9 70.9 78.4 89.2 93.7
Min. bending radius mm 770 851 851 941 1071 1125
Approx. cable weight kg/km 7050 8750 8900 10200 15950 18700
Copper weight kg/km 1250 1680 1780 3570 4160 5950
Current rating at 25 °C A 135 170 170 205 250 295
Phase conductor Ω/km 0.565 0.393 0.393 0.277 0.210 0.164
Earth conductor Ω/km 0.795 0.795 0.565 0.393 0.277 0.277
Armour Ω/km 0.92 0.79 0.79 0.50 0.38 0.30

Selection note: before ordering, ask our engineers to confirm the conductor operating temperature, the sheath colour, the core colour code, the ambient conditions behind the 25 °C current rating and any derating for drum or grouped installation. Minimum bending radius is given per size in the table.

Standards & References

Applicable standards and compliance

  • Design specificationMGM 112, the armoured rubber power cable specification in the Turkish Hard Coal Enterprises MGM mining cable series; Type 321 is its unscreened 1900/3300 V design.
  • Conductor referenceStranded tinned copper conductors to IEC 60228 Class 5.
  • Voltage scope1900/3300 V rated voltage and 7.5 kV test voltage.
  • ApprovalsMine-authority approvals, type-test reports and marking requirements are confirmed and quoted per order.

Construction

Material and build-up

MGM 112 Type 321 is a round four-core cable. Three phase cores and one earth core, all unscreened, are laid around a central elastomeric cradle that keeps them apart, then covered by a rubber bedding, galvanized steel pliable armour and a heavy-duty chloroprene sheath.

  • Conductor: stranded tinned copper, IEC 60228 Class 5, from 276/0.40 mm (35 mm²) to 608/0.50 mm (120 mm²).
  • Phase insulation: EPR, 3.0 mm thick on all sizes, with no screen over it.
  • Earth core: unscreened tinned copper conductor, 1×25 to 1×70 mm², with EPR insulation 3.8 to 5.0 mm thick.
  • Elastomeric cradle: shaped rubber centre that positions the four cores so they do not touch each other.
  • Bedding: rubber-based bedding compound, 2.5 to 5.0 mm radial, over the cradle layup.
  • Armour: galvanized steel pliable armour, 7/0.90 mm up to 7/1.25 mm strand size.
  • Outer sheath: heavy-duty chloroprene compound, 5.3 to 7.2 mm radial.

FAQ

Selection questions

What is MGM 112 Type 321 and how does it differ from Type 331?

Both are 1900/3300 V armoured MGM 112 cables with tinned Class 5 copper, 3.0 mm EPR phase insulation, steel armour and a chloroprene sheath. Type 321 has no screens and keeps its cores apart on an elastomeric cradle; MGM 112 Type 331 puts a tinned copper / nylon braid over each phase core and lays the cores in contact. Type 321 also starts at 3×35+25 mm², while Type 331 is available from 3×25+16 mm².

Is MGM 112 Type 321 the same as MGM 111 Type 321?

No. The type numbers are the same but the specifications are different. MGM 111 Type 320 and 321 are 3.3 kV cables under the MGM 111 specification, with semiconducting layers around the insulation and a tinned copper / nylon braid over the insulated cores. MGM 112 Type 321 has no screens and uses a cradle layup. Always quote both the MGM number and the type number when ordering.

Which details are needed for a quotation?

Send the size such as 3×95+70 mm², the length per drum and total quantity, the system voltage and protection or earthing arrangement, any sheath marking requirement, and the mine authority whose approval or test report you need. Our engineers confirm the construction and return the approved datasheet with the quotation.

When should I use a 1.1 kV MGM 112 type instead?

If the machine runs at 660 or 1100 V, the screened MGM 112 Type 201 and 211 are lighter and smaller: a 3×50+35 mm² Type 211 weighs 7080 kg/km against 8900 kg/km for Type 321 of the same size. For 6.6 kV distribution see MGM 118 Type 6010, or browse the MGM mining cable category.

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Quality Assurance

Testing at every stage in our own workshop and laboratory, from incoming copper to the packed drum.

Bare copper wire bobbins inspected before stranding at the TEBAOFLEX factory

Raw Material Inspection

Every batch of copper rod, rubber compound and reinforcing material is checked before it reaches the line.

  • Copper: conductor resistance, elongation and surface condition on incoming rod and drawn wire
  • EPR, CPE, PUR and silicone compounds: hardness, tensile strength, elongation and ageing samples from each mix
  • Suppliers and batch numbers are recorded so every drum can be traced back to its materials
Operator monitoring an extrusion line control panel in the TEBAOFLEX workshop

Manufacturing Process Control

Stranding, insulation extrusion, core assembly and sheathing run under recorded process parameters.

  • Class 5/6 stranding with lay length and tension monitored for trailing and reeling flexibility
  • Continuous-vulcanisation extrusion with wall thickness and spark tests logged on every length
  • Operators sign off each stage before the cable moves to the next machine
3.5 kV voltage withstand test station in the TEBAOFLEX laboratory

Electrical Testing

Finished lengths go through the routine tests required by the referenced VDE, ICEA, IEC or NEK standard.

  • Conductor resistance and insulation resistance on every length
  • Voltage withstand (3.5 kV and higher) and partial-discharge measurement in the shielded HV laboratory
  • Screen and pilot-core continuity checks for mining and reeling constructions
Tensile testing machine for conductor and sheath samples

Mechanical and Ageing Tests

Samples from production are tested for the duty a mining, crane or submersible cable will actually see.

  • Tensile strength and elongation of insulation and sheath before and after ageing
  • Hot-set, ozone, oil-immersion and low-temperature bending tests
  • Constant-temperature water bath for insulation resistance of submersible constructions
Single-cable vertical flame test chamber

Flame Test and Final Inspection

Before packing, the cable is checked against the order and the flame-performance requirement of its standard.

  • Single-cable vertical flame test to IEC 60332-1-2 where specified
  • Metre marking, printing, drum length and appearance inspection
  • Test report and packing list issued with every shipment

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