Series of Posts on Preventing Common Problems in Instrument Installation (IV)
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Series of Posts on Preventing Common Problems in Instrument Installation (IV): We invite fellow enthusiasts to actively participate in the discussion of these issues. Constructive suggestions will be rewarded generously; having relevant images will earn additional points as a bonus. By sharing such problems and their solutions, we can avoid similar issues arising in future installations and create a favorable environment for maintenance work. Thank you! 4. The cable tray installation did not include grounding protection for the cable tray. Analysis and prevention: The entire length of the metal cable tray and its supports should have at least 2 points for grounding or bonding to earth. The ends of the connecting pieces should be connected to grounding wires with a copper core of at least 4 mm2 in cross-section. Grounding or bonding to earth is crucial in order to ensure the safe operation of the power supply circuits. In some design schemes, a protective earth wire made of copper or galvanized flat steel is installed along the bottom of the cable tray throughout its length, with several electrical connection points provided at each section of the tray; this ensures very reliable grounding or bonding protection for the cable tray.
Please discuss how to address the grounding issue if non-metallic cable trays are used
What is the purpose of grounding non-metallic cable trays? In short, it’s an anti-static grounding. As for the jumper wire, since there are no explicit requirements, let’s add it for now. It seems that whether the non-metallic cable tray is grounded or not has little impact
What does a metal bridge frame refer to? For example, is the working platform made of a steel frame?
Unlike galvanized cable trays, ordinary fiberglass reinforced plastic cable trays cannot form a shielding layer, and thus do not provide good interference resistance for weak electrical signals. However, there are also special fiberglass reinforced plastic cable trays as described below. The following is from the internet. Since fiberglass itself does not have the capability to block electromagnetic interference, ordinary fiberglass cable trays do not provide shielding capabilities. However, materials that can provide shielding can be added, such as mesh-like metal nets or other electromagnetic materials. It is likely that ordinary fiberglass manufacturers are not very familiar with which materials offer the best shielding effect. Yet it is easy to add such materials to fiberglass – once they know what needs to be added, it is straightforward to incorporate it. Therefore, it is absolutely no problem to enable fiberglass cable trays to shield electromagnetic fields. Moreover, the production of fiberglass materials that can block electromagnetic interference is now well-established. The main methods include: 1. using conductive resin; 2. adding carbon fabric. Of course, its price is much higher than that of ordinary fiberglass materials. What are the installation considerations for fiberglass reinforced plastic cable trays that are designed to shield electromagnetic fields? Since such cable trays need to shield electromagnetic interference, they are usually used in electrified environments, which means that grounding must be taken into account. The specific situations can be categorized as follows: 1. In ordinary environments, grounding is not necessary; 2. Grounding is required in environments with explosion hazards (static electricity can generate sparks that may reach the critical level for an explosion, posing a danger); 3. The surface of fiberglass reinforced plastic cable trays can be treated with galvanizing, electrostatic spraying, or hot-dip galvanizing, which facilitates grounding; 4. Both the ends of the cable tray must be grounded, and connections between sections of the tray should be bonded together.
Most non-metallic cable trays are reinforced with metal frames, and these metal frames have electrical conductivity; should they be treated in the same way as metal cable trays? This is where we hope for in-depth discussions.
A metal cable tray is a specialized channel used in electrical or instrumentation applications for laying cables, made of metal materials such as aluminum alloy and carbon steel with hot-dip zinc coating.
Our company’s instrumentation department has been using cable trunking with fiberglass straps and shielding nets, and the results have been quite good.
Is it easy to maintain? Is it easy to break or get crushed? Is construction also more difficult than with aluminum alloy?