7/29/2019 Cable Glands & MCT

http://slidepdf.com/reader/full/cable-glands-mct 1/3

Cable Glands 

Why Do We Use Cable Glands? 

• To firmly secure cable entering a piece of equipment

•

To maintain the ingress protection of the piece of equipment (minimum of IP54 for 'e' and 'n' typeenclosures. Where the enclosure wall thickness is less than 6mm a sealing washer or threadsealant will be required to maintain IP54 protection)

• To maintain earth continuity between a piece of equipment and any armoring in the cable

• To ensure containment of an internal explosion in flameproof equipment

Technical article on Multi Cable Transit Block Sizing

My journey started with our clients comments for designing the frame and we had noinput for MCT frame but have all the cable schedules and relevant information wereavailable with us . Lots of documents to be refer and complete the exercise withminimum time.

After review of all the input, idea of MCT and started ........This is the First time I hadgot an opportunity to design the MCT Frame sizing for entering cables from field toControl Room. This designing is generally done by Vendor but we have decided to do atour end as we are developing the procedures for our organization Mott MacdonaldConsulting India Pvt Ltd. Which may be benefited for me in future.

Really I was wondering where from I should start....after spending 2 ½ hrs I startedwith listing all the Cable description and its OD sizes and then geared up for furtherdesigning.

Brief Description: Multi Cable Transit Block (MCT) protects against fire, water, gas,smoke, pressure, shock, chemicals, EMC, damaging insects, cold and human error. The

product consists of two components- a frame and packing blocks. The efficient seal isachieved when the packing blocks are pressed together around cables and pipes in theframe with the aid of a compression plate. The heart of the MCT system is a rubbermaterial called Lycron, from which the insert blocks are made. It is extremelyresistant to fire but MCT is much more than a fire explosion barrier. In addition toextreme heat and enormous pressure chtransithe transits withstand smoke, extremetemperature changes, vibration, sound, damaging insects, chemicals and the effects ofageing.The original standard block, together with the newly developed, flexible Add block,creates even better opportunities for fast, simple and safe installation. The U-blockssimplifies and improves certain types of installation and is a complement to both theother block types.

STANDARD BLOCK SEAL BLOCK: The Standard Blocks is based on the original patent.It's the first choice when one is certain of the cable diameter. Cable diameters otherthan standard dimensions can be supplied to order. ADD BLOCK SEAL BLOCK: The Add Blocks is the solution when you are not sure inadvance of the exact dimension of the cable or pipe. Each Add Block can be adaptedto five different cable dimensions. The block has four insert sheets, which can be

7/29/2019 Cable Glands & MCT

http://slidepdf.com/reader/full/cable-glands-mct 2/3

peeled off. With these fitted in the block it can be adapted to five different cabledimensions. Thanks to the locking devices the insert remain in position and there is norisk of "telescoping".

U-BLOCK : The U-Block is complement to both the Standard Block and Add Block. Withthe U-Block it is possible to change the outer dimensions of a block so a narrow cable

can be placed beside a larger on the same row.

MCT SIZING CALCULATION:Step 1: Input Cable details including cable type, cable size and overall diameter ofcables.Step 2: Segregate the cable as per philosophy.IS and Non IS cable, DCS, ESD cables, F&G cables etc.Step 3: Deciding the Basic MCT Frame design requirements.

a. Selection of standard frame type from available catalogue.RGBO/RGGO/RGS. depending upon the application requirement.

b. Multiple Frames selection.Horizontal multiple frames, Vertical multiple frames and combined Horizontal andVertical multiple frames etc.

c. ComponentsStay plate, Compression plate, STG end packing, PTG press wedge and End packingpuller for STG.

Examples:STAY PLATE: To be placed between each row of blocks. Stayplates simplifiesinstallation, increases Stability and anchors blocks within the frame. Plates come ingalvanized or stainless steel,

Aluminium and brass.

COMPRESSION PLATE: Usually assembled above top row of blocks. The plate bolt istightened to compress blocks around cables, while providing room for STG endpacking. Comes in GRP, Glass fibre Reinforced polyester.

STG – ENDPACKING: Installed between compression plate and the top of the frame,completing the Seal. Made of Lycron with galvanized or stainless steel fittings.

PTG - PRESSWEDGE: Can be used as an alternative to compression plate and STG. Canalso be placed any where in the frame .Made of Lycron, with galvanized or stainless

steel fittings. Must always be installed in combination with stay plate.

END PACKING PULLER:

d. Material for FrameMaterial to be defined for the entire range of items listed above to proceed further.(Available materials are SS, Galvanized, Mild steel, aluminum etc)

7/29/2019 Cable Glands & MCT

http://slidepdf.com/reader/full/cable-glands-mct 3/3

Step 4: MCT Sizinga. Prepare table as shown below for cables OD and its Block size.

Cable Description O.D Cable Gland size Block Size1P X 1.5 MM² 15 M20 20/15

2P X 1.5 MM² 17 M25 30/176P X 1.0 MM² 21.5 M25 30/2210P X 1.0 MM² 24 M32 30/2420P X 1.0 MM² 32.5 M40 40/33

b.Based on the above information like number of cable and cable OD; selectwindow size.

c. Some of the reference frame dimensions are given in below table. 

d.Weight in kilograms

e.Example frames are shown below.

Step 5: Larger size cable to be routed from bottom and smaller size will be on top ofthe bottom layer as shown in below frame.

DESIGNED MCT FRAME FOR INDIVIDUAL TYPE LIKE DCS, ESD AND F & G.

INSTALLATION GUIDE:

-GENERAL ARRANGEMENT

-INSTALLATION PROCEDURE:

Even my seniors are very happy to see the manual calculations for MCT sizing.

Really I feel very proudly to publish this post..on MCT sizing design

Never hesitate to make an effort to do something. Think of efforts and appreciationwill follow you automatically.

Regards,Dattatray K.Nikam