MAIN DISTRIBUTION FRAME (MDF) CABINETS AND DP

MDF,CABINETS AND DP
MAIN DISTRIBUTION FRAME (M.D.F).

Frame in the exchange used for making cross connections between the incoming cables and exchange equipment. On the line side of the frame the cables terminate on protector strips.

It is a connecting/testing point where incoming cable (from switch room) out-going cable to cabinet are terminated. It is of two types
(i) Wall Type.
(ii) Floor Type.

Both sides cables are terminated systematically and join them with a wire i.e. called jumper wire. By this we can change or shift a number easily.
DEFINITION OF CABINET:
It is a small testing point where primary and secondary pairs are terminated.

CABINET CAPACITY:
Total number of primary and secondary pairs those terminated in a cabinet is called capacity of cabinet.

CONSTRUCTION OF CABINET:
It is an almirah made of iron and fiber. It is fixed on the stand made of bricks and cement.

TYPES OF CABINETS:
1 50/100 poles mount cabinet
2 300/400 Single door cabinet
3 600/800 Double door cabinet
4 500/700 cabinet
5 1000/1400 cabinet
50/100 PAIRS CABINET
This cabinet is a small box made of iron or plastic. It is equipped with three C.T boxes each has 50 pairs. One CT box is for the primary pairs (1 to50), 2 C.T boxes (50 pairs of 5 DPS each) for the secondary pairs. Counting of the primary CT box is done pair-wise and the secondary CT box, DP wire. This cabinet is 8’ high from the ground.

300/400 PAIRS CABINET
This cabinet is a big box made of iron or plastic. It is equipped with 7 CT boxes and each CT box has 100 pairs. 3 CT boxes i.e. 300 pairs for primary and 4 CT boxes 8.3 400 pairs for secondary. These CT boxes are fitted in the following ways.
In CT box of the top is called secondary or outgoing and the next one is known as primary or incoming. The same procedure is used for other CT boxes. The counting of the primary CT boxes is done pair-wise and that of secondary DP wise.

600/800 PAIRS CABINET:
This cabinet is a big box made of iron or plastic. It is equipped with 14 CT boxes having 100 pairs. The six CT boxes used for primary and 8 CT boxes for secondary. The CT boxes are fitted in the following ways: First CT Box of the top called secondary of outgoing. The proceeding one is called primary or incoming. The same procedure is used for other CT boxes, the counting of the primary CT boxes is done pair-wise and that of secondary DP wise. The 600/800 cabinets are fitted on bricks.

In new types of cabinet:
1. Counting of DPS is started from up to down.
2. Counting of pairs is started from left to right.
3. The color of primary terminating strip is White.
4. The color of secondary terminating strip is Gray.
5. Primary and Secondary pairs are connected with the help of insertion tool.
6. Primary and Secondary cables are terminated on the upper side of the terminating strip and jumper wire is terminated on the lower side.
7. It is made in single and double side formation.
Each CT Box consists of 100 pairs but the procedure of termination of cable in the cabinet is quite different. The first row of left side in vertical position is secondary and then primary and then again primary while fourth one is secondary.

ADVANTAGES OF CABINET:
1 It is a testing point where primary and secondary pairs are terminated.
2 50 and 100 pairs C.T. Boxes are terminated.
3 Cable is terminated on rare side of the CT box.
4 Primary and secondary pairs are connected with the jumper wire on the front side of the CT box.
5 The counting of CT boxes is started from up to down.
6 The formation of CT boxes in the cabinet is first secondary, second primary then secondary and again primary and so on.
7 Faulty cable pair can be changed easily.
8 A chart is placed in the cabinet to note the primary cable and DPS numbers and their location.
9 There are holes in the lower sides of the cabinet to enter the cable.
10 These are guided rings in the cabinet to pass the jump wire, and keep them in compact formation.
11 The counting of DPS is started from left to right.
12 The counting of pairs is started from up to down and left to right.
13 Primary cable is inserted from the left side of the cabinet holes and secondary cable from the right side.