On the contrary, it can also be calculated according to this formula that how thick wire 10W * 88 / 220V = 4A is required for 88 guns, and then check the comparison table 4a, and the wire diameter is 3 * 0.75.
The length of pipe slot is the same as that of cable.
First, it is necessary to determine which layer the front-end equipment is mainly concentrated.
075 line diameter is 4a.
If it is 25 ￠ iron pipe, one line shall be reduced from the original basis (because the wall thickness of iron pipe is thicker than PVC pipe).
See the following table: what type of wires are selected in the power line diameter quick look-up table.
Are you sure it’s too long? If it is too long, where should the sub distribution room be set and how many? If there is a sub distribution room, the number of switches will change accordingly.
IV.
according to the above problems, the wire configuration method is sorted out.
2、 Selection of cable type: generally, 75-3 and 75-5 lines are selected as video lines, and there are also a few special lines such as Elevator dedicated lines.
Where the equipment is concentrated, you can choose to use the main slot.
Comparison table of cable capacity of pipe slot (take class V wire as an example, other models are similar, which can be referred to) 1.
If it cannot be confirmed, it must be understood by the business.
One gun is calculated according to 10W power consumption, and the number of guns available for a power line with 3 * 0.75 line diameter is 88.
The calculation formula is 4A * 220V / 10W = 88.
The power consumption of a single branch is generally 5-12w.
The power cord is selected according to the actual situation.
Then prepare 110m 75-3 video line, rvv2 * 0.5 power line and rvvp3 for both guns × 0.5 monitoring cable is enough.
The longest distance line length of a single gun is generally the sum of the length and width of the building area plus the length of the downline in the monitoring room and the reserved line at the front end.
The total length of line for gun B is 37m.
Number of statistical information, including each room and machine room, Fill in the point distribution table; 2.
If there is no drawing, you need to know the basic information of the network from the business, such as building height, area, line well location and other basic information.
1、 Estimation of cable length the estimation of cable length can be divided into two situations: 1.
3、 The PVC pipe of 25 ￠ specification commonly used by the company shall be selected for pipe slot, which can wear 8 75-3 video lines and 6 75-5 lines; 5 75-5 video lines + 1 power line can be used for mixed threading.
In this way, the reserved line length of a gun is 1.5 + 3.5 + 2 = 7m, and then the total length of the line is calculated according to the length dimension marked in the actual environment of the drawing, Take the following figure as an example: the building is 40m long and 30m wide, and the monitoring center is in the middle of the room, so the length of the line for gun a is 40m + 15m (half of the 30m width) + 7m (reserved line) = 62m.
A single transformer can supply 6 guns, up to 7 guns.
If the elevator wiring is the building wiring and there is an elevator, the floor from which the cable enters the elevator shall be calculated according to the following formula and then connected: floor ÷ 2 + 1.
If there are drawings, find out the line direction on the drawings and determine the location of the monitoring room; If it is a building project, the distance and location of the off-line well in the monitoring room shall be determined.
Take a 16 storey building as an example, 16 ÷ 2 + 1 = 9 should be wired at the 9th floor to enter the elevator.
3.
PVC slot (model) 20 * 1024 * 1439 * 1959 * 2299 * 2799 * 40100 * 1002, class V wire (number) 2491632483, PVC pipe (model) ф sixteen ф twenty ф twenty-five ф thirty-two ф forty ф 504.
The general slot full rate (slot full rate refers to the proportion of the space occupied by the cable after it is put into the slot) the specification requires that the slot full rate of weak current is 40% and that of strong current is 50%.
3.
The general wiring principle of engineering construction is to take a straight line nearby and try not to detour.
The calculated result is the actual number of floors.
According to the quick look-up table of power line diameter, the maximum current load of 3 *.
The 75-3 video transmission distance is generally 200m, and the 75-5 transmission distance is generally 400m.
2m is reserved for the monitoring cabinet (for short-distance movement of the cabinet).
If the wiring distance exceeds 50m and there are many guns, the power line can be wired by bus, and the transformer can be placed in the front-end equipment box.
Class V wire (number) 236915245, zinc wire slot (model) 25 * 2525 * 5025 * 7550 * 5050 * 100100 * 1006, class V wire (number) 715223060120 capacity formula: pipe slot capacity = int (pipe slot area * k) k = 0.012 for cat5utp, for example: PVC slot algorithm for 100 * 100: 100 * 100 * 0.012 result: 120.
Determine the model and length of each bridge..
However, according to the actual work experience of the engineering department, the cable corners and turns are also required in the wiring process, which will generally increase by 15% on the basis of the original length, that is, 62 * 10% = 10m, Then the actual length of gun a is 62m + 10m = 72m.
During the construction of the monitoring project, the wire configuration is often encountered when making the scheme, such as wire length calculation, wire selection, pipe slot selection, etc.
calculation of auxiliary materials 1.
At present, the power supply distance of 24V and 12V transformers commonly used by the company shall not exceed 50m.
The size of the slot is determined by the number of lines to be laid in the main slot.
2.
It is sufficient to select rvv2 * 0.5 two core wires.
Then estimate the vertical length according to the floor height (the general floor height is 3.5m, and the first floor is 7m), and then calculate the approximate total length of the cable according to the transverse distance of the cabinet offline well.
The standard calculation length of a line is: 1.5m is reserved for the front-end gun, and 3.5m is reserved for the rear-end gun from the ceiling to the ground, that is, the vertical distance from the ceiling to the monitoring cabinet.
Determine the direction of the reason; 4.
The length of line for gun B is 10m + 15m + 7m = 32m, plus 15%.
