Teach you the wiring strategy and skills for elevator monitoring

Teach you the wiring strategy and skills for elevator monitoring

Xuzhou Zhongshun Elevator Equipment Co., Ltd. specializes in selling various elevator accessories, elevator motherboard frequency converter maintenance, elevator overhaul and renovation, elevator decoration, and non-standard customization of elevator arrival light control panel

With the popularization of security monitoring, camera systems have also been installed in elevators. However, for complex environments like elevators, many engineering video surveillance images are subject to varying degrees of interference in the elevator shaft environment. So how to solve it? Please read this article!

The current situation of elevator interference

1. Horizontal stripes roll up and down;

This phenomenon is manifested as the stripes continuously rolling up or down, and the stripes are relatively wide. It appears to be interference, but it is not caused by external electromagnetic waves. If we disregard the stripes, the image is clear. This phenomenon accounts for more than 80% of the image interference caused. It can be said that this phenomenon is definitely a problem with the grounding potential, which refers to the potential difference between the ground of the front-end equipment and the ground of the central control room. This problem cannot be tested by a multimeter. If the measured number is zero, it does not mean that there is no potential difference. The only way is to disconnect its circuit, that is to say, disconnect one of the two ends of the ground (* choose the front end). If neither end of the ground wants to break, it may affect lightning protection. Add a ground isolation device to solve this problem. This type of equipment is passive and can be connected in series to any end of the coaxial cable. It is easy to install and has good performance, completely eliminating this stripe phenomenon. The picture shows the Utep signal isolator.

2. Mesh interference;

This phenomenon results in poor image quality, with almost no visible objects, intermittent images, and freezing of the screen. This phenomenon is due to the broken or short cores and shields of the cables. This situation mostly occurs at the joints, and there are also a few cases where the wiring was not properly constructed. Interference caused by welding problems or poor quality of joint components also accounts for a large proportion in engineering.

3. Interference of Space Electromagnetic Waves

This type of interference source is relatively complex, mainly due to strong radiation sources or high-power devices operating in the front-end equipment, cables, and near the terminals. Mainly manifested as image distortion, jitter, etc. So before construction, it is necessary to have an understanding of the surrounding environment and try to avoid radiation sources as much as possible. In the case where interference is unavoidable in a completed project, only anti-interference equipment can be added. This method is relatively economical, fast, and has guaranteed images.

Application of Twisted Pair Transmission for Elevator Monitoring

For the complex environment inside the well, the use of twisted pair transmission can be carried out according to the following three recommended solutions:

A) Route in the middle of the shaft

1. Choose unshielded high-quality Category 5e cables.

2. Drill a hole on the wall in the middle of the shaft to lead out the line.

3. Cables should be bundled with accompanying cables, and cable bundling below the middle of the shaft should be reserved

4. The transmitter should be selected based on distance requirements and powered separately.

B) Elevator machine room outgoing line

1. Choose unshielded high-quality Category 5e cables.

2. Cables should be bundled with accompanying cables, with reserved bundling for cables below the middle of the shaft and tight bundling for cables above the shaft.

3. The cables in the elevator machine room should not be routed through strong electrical cable trays, and should be separated from the cable trays and connected to the monitoring center as soon as possible.

4. The transmitter should be selected based on distance requirements and powered separately.

C) Installation of elevator machine room

1. Install a transmitter in the elevator machine room using the video cable provided with the accompanying cable as the front-end medium.

2. The transmitter selects passive or active based on the length of the video cable

3. The receiver is installed in the monitoring center, and passive or active receivers are selected based on the distance of the twisted pair cable.

In addition, the transmitter and elevator grounding system should be carried out separately. We suggest grounding the remaining wires in the network cable at the monitoring center, and grounding the receiver is to ensure that the equipment is protected from overvoltage damage. It is often difficult to achieve independent grounding devices for the various types of grounding mentioned above, and a common grounding device is usually used. Generally, it is required that the grounding resistance of the shared grounding device should not exceed 1 Ω. The grounding wire can be connected to the PE wire in the building distribution room using a copper core wire (PE wire) with a cross-sectional area of not less than 16 square millimeters, and can be laid in the same route as the elevator power cable. The end of the grounding wire is connected to the auxiliary equipotential board in the elevator machine room.

Pay attention to the following points when tying network cables:

1. Choose a qualified and flexible unshielded network cable.

2. First, fix it on the accompanying cable with a thick zip tie.

3. Tie the network cable with a thin zip tie and secure it inside the thick zip tie.

4. The spacing between thick zip ties is 30 centimeters, and 3 centimeters are reserved for each section of the network cable.

Precautions for twisted pair wiring

1、 Twisted pair cables must comply with the national twisted pair product standards:

1. The twisted pair used should have a pure copper core The wire diameter is 0.5 millimeters

2. The resistance of a single core 100 meter resistor is 9.38 ohms, and the resistance of a 305 meter wire in a box is around 28 ohms, not exceeding 30 ohms

3. The twisting density should reach the standard of Class 5 wires

4. Flexibility and flame retardancy must meet national inspection standards.

2、 If used outdoors, please use outdoor waterproof twisted pair cables.

3、 During engineering wiring, it is prohibited to mix and contact with high voltage cables or equipment, nor to place them together with frequency conversion equipment or communication signal generators.

4、 The four pairs of wires inside the cable transmit one signal per pair, so video can be transmitted simultaneously. Audio and control signals are used to prevent the transmission of high current power within the cable. If a pair of low voltage power supplies DC12V needs to be controlled within 150 meters, AC24V needs to be controlled within 300 meters, and the control signal needs to be controlled within 1000 meters.

5、 Active and partially passive products have built-in surge protection and require grounding. For outdoor applications, they can be grounded together with the camera. Please note that the grounding electrode resistance must be qualified (reference value 4 ohms)

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