In-depth analysis of cabling strategies and techniques for elevator monitoring

Elevator interference status

1. Scroll up and down of horizontal stripes

This phenomenon shows that the stripe keeps rolling up or down, And the stripe is relatively wide. It looks like interference, but not external electromagnetic waves. If the stripe is left blank, the image is clear. This phenomenon accounts for more than 80% of image interference. It can be affirmed that the ground potential problem refers to the potential difference between the ground of the front-end device and the central control room, the problem is that the multimeter cannot be tested. If the measured number is zero, it does not mean that it does not have a potential difference. The only way is to disconnect its loop, that is to say, it is best to choose the front end to disconnect the ground at both ends ). If the two ends do not want to be disconnected, it may affect the lightning protection. This equipment is a passive device. As long as it is connected at any end of the coaxial cable, it is easy to install and works well, and can completely eliminate this stripe phenomenon. It is an excellent signal isolator.

2. Mesh interference

In this case, the image quality is very poor, and basically no object is visible. Sometimes there is no image, and the image crashes. This is becauseCableFor the sake of Wire Core and shield breaking and short. Most of these cases occur on the connector, and some of them are not properly constructed during cabling. Interference caused by welding problems or poor connection quality also accounts for a large proportion of projects.

3. Spatial electromagnetic interference

This interference source is complex, mainly because there are strong radiation sources or high-power devices in front-end devices, cables, and terminals. The main features are image distortion and jitter. Therefore, we should understand the surrounding environment before construction and try to avoid radiation sources. Only anti-interference devices are used when interference is unavoidable in a completed project. This method is relatively economical, fast, and images are secure.

Elevator monitoring application for twisted pair wires

The environment in the well channel is complex. You can use the twisted pair wire transmission method according to the following three recommended solutions:

A) Middle Route of the well track

1. select non-shielded high-quality cat5e cables.

2. Open the outlet in the middle wall of the well.

3. cables are bundled with accompanying cables, and cables below the middle of the shaft must be reserved.

4. the transmitter is selected based on distance requirements, and the transmitter shall take power independently.

B) elevator room Outlet

1. select non-shielded high-quality cat5e cables.

2. cables are bundled with accompanying cables. The cables below the middle of the shaft must be reserved and the upper cables of the shaft must be bundled.

3. cables in the elevator data center should not go through a strong cable tray. They should be connected to the monitoring center as soon as possible.

4. the transmitter is selected based on distance requirements, and the transmitter shall take power independently.

C) elevator room installation

1. Use the video cable that comes with the accompanying cable as the front-end medium to install the transmitter in the elevator room.

2. The transmitter selects a passive or active Transmitter Based on the video length.

3. the receiver is installed in the monitoring center. Select a passive or active receiver based on the distance between the twisted pair wires.

In addition, the transmitter and the elevator grounding system should be separated. We recommend that the remaining cables in the monitoring center be grounded to ensure that the devices are protected against overvoltage. It is often difficult to implement independent Grounding Devices for various types of grounding systems. Generally, the grounding resistance of the shared grounding device is not greater than 1 Ω. The ground wire can use a copper core wire (pe) with a cross-sectional area not less than 16 mm². The first end is connected to the pe in the building distribution room and can be laid along the same path as the elevator power cable, the end of the grounding wire is connected to the auxiliary equipotential board in the elevator room.

Pay attention to the following points during network cable binding:

1. Select a soft unshielded network cable.

2. Fix the cable with a rough cable.

3. Bind the network cable with a thin cable tie and fix it in a thick cable tie.

4. The distance between the cable ties is 30 cm, and each segment of the network cable is reserved for 3 cm.

Cable cabling considerations

1. Twisted Pair wires must comply with national twisted pair wire Product Standards:

1. The twisted pair wires must be copper cores. The wire diameter is 0.5mm.

2. The single-core 9.38-meter resistance is 305 ohm, and the resistance of a box of-meter cables is around 28 ohm, not exceeding 30 ohm.

3. The twisting density must meet the five-class line standards.

4. Flexibility and fire resistance should meet the national inspection standards.

2. for outdoor use, please use outdoor waterproof twisted pair wires.

3. Hybrid contact with strong voltage cables or equipment is prohibited during Engineering cabling, and cannot be placed together with frequency conversion equipment and communication signal generators.

4. Each pair of four lines in the cable transmits a single signal, so videos can be transmitted simultaneously. Audio and control signals prevent transmission of large current power sources in cables. If you need a pair of low voltage power supplies in the network cable, the dc12 V is controlled within 150 meters, the AC24V is controlled within 300 meters, and the control signal is controlled within 1000.

5. built-in surge protection for active and some passive products, which must be grounded. outdoor applications can be grounded with cameras. The reference value must be 4 ohm)

6. The video line from the camera to the transmitter should be as short as possible to ensure stable signal quality.

Interference brings some difficulties to elevator cabling. During cabling, the choice of twisted pair cables is very important. I hope you can learn more about this.