For distribution cabinets in the power distribution room, is it better to choose MNS or GGD, etc.?

Each has its advantages and disadvantages, and depending on the habits of your own company, it’s easier to use a new project or MNS

I asked a few front-line employees, and they thought GGD was convenient as well, if not more so

If a malfunction occurs in the MNS drawer cabinet, replacement spare drawers can be used to resolve the issue quickly

Compared to fixed cabinets, drawer cabinets are safer and more reliable because the various circuits are separated from each other. In GGD cabinets, several circuits are located in the same working area, resulting in poor safety. By using drawer cabinets, it is possible to replace a faulty drawer with a spare one when there is a problem, **which reduces the downtime and is very convenient.

From the perspective of ease of maintenance, drawer-type cabinets are superior to GGD cabinets; when one drawer is damaged, a spare drawer can be used without affecting the other circuits. When maintaining and replacing the GGD cabinet, working on the circuits adjacent to it poses a risk of electric shock; meanwhile, shutting down those adjacent circuits affects production. The downside of MNS cabinets, in my opinion, is that they are not suitable for using thermal relays; whenever a thermal relay trips, it’s necessary to pull out the drawer to reset it. If I had to choose, I would definitely use an MNS cabinet with a motor protector.

Ahah, as a fellow sea lover, I’d like to share my personal opinion for your reference! Regarding whether to use MNS or GGD cabinets for low-voltage MCCs, this is a topic that has been discussed by us, electrical professionals in the petrochemical industry, but the best choice is still the MNS cabinet type! Regarding the eight points raised by the original poster, here are the comments: 1. It is easy to conduct inspections, especially with thermal imaging. It can be said that this approach has a slight advantage in certain aspects, but it poses significant security risks, which is undeniable. Moreover, it is worth considering whether thermal imaging can be used for inspections – if the cabinet doors cannot be opened, how can thermal imaging inspections be carried out? 2. Easy to maintain and repair. Regarding the maintenance aspect, I can’t agree with this; in fact, MNS drawer cabinets are easier to maintain and more convenient for the repair and fault resolution of MCCs in the petrochemical industry. 3. Good heat dissipation, with minimal mutual influence between heat generation. Regarding cabinet-based cooling, with different installation methods for the main components inside the cabinet, it can only be said that there is a slight improvement ； And mutual influence between heating at the top and bottom should exist; there’s no such thing as minimal mutual influence! 4. It is not good if the cabinet door cannot be opened. The issue of the cabinet doors not opening actually occurs with both types of cabinets during operation (the status of the main circuit breaker is interlocked with the cabinet doors, preventing them from being opened)! 5. No power receiving and transmitting claws prone to problems. Regarding the issue of power supply tools, there should be no such problem anymore. Since the MNS cabinet type was developed in the late 1970s, improvements in manufacturing techniques have been made; many brands of MCC drawer cabinets now do not require power supply tools (for sliding them in or out). Thirty-five years ago, when I was working in electrical maintenance, the drawers of imported MCC units required tools such as keys to swing them in or out; but nowadays, with ABB’s MNS, MOLLER 6000, Siemens’ 8P series, and similar products, no special tools are needed to operate the drawers! 6. There are no connectors in the secondary circuit that could have poor contact. Regarding secondary circuit issues, there are indeed contact problems with the secondary plugins, but as long as we pay attention to maintenance and the quality of operations, most of these problems can be avoided ； Once a GGD cabinet experiences a second failure, on-site maintenance becomes complicated and the recovery time is long, which is something the petrochemical industry tries to avoid. 7. When the quality of available options cannot be controlled, it is better to choose GGD cabinets; MNS cabinets require a higher standard regarding brands. This problem does exist; the key lies in factors such as the role of the company or owner, as well as the oversight by technical personnel and the establishment of standard technical requirements for procurement. As technical professionals, it is their responsibility to take initiative and to prepare detailed technical attachments in advance in order to regulate and hold suppliers accountable, thereby working together to improve quality. 8. The space is likely to be large. Regarding views on spatial issues, it can only be said that each has its merits, and no generalization can be made. In short, for devices that require a high level of process continuity, using MNS cabinets with reliable quality is undoubtedly the best choice! Is it advisable to use automatic transfer switching for the 380V low-voltage double-bus segmentation? How is it in practical use? This issue really doesn’t need to be discussed; it’s clear that segmental automatic transfer switching is the better approach. Its practical performance is excellent, especially in situations such as faults in the distribution system or voltage fluctuations, as it can play a crucial role by helping maintenance personnel restore power supply to the equipment on site quickly. Is it safe to use automatic transfer switching for 10KV double-bus sections? How is it in practical use? Same opinion as before! Furthermore, the concept of dual busbars proposed by the original poster generally does not apply to medium-voltage and low-voltage distribution systems; in particular, in distribution systems within plant areas, there is usually no issue of dual busbar segmentation, but rather single busbar segmentation ； Double-bus segmentation is mainly used in high-voltage power distribution systems (such as main substations, regional substations, or power plants), and it is generally not required in plant and station power distribution systems; perhaps the original poster made a mistake!

Recently, for steel plant desulfurization and denitration projects, owners always require GGD. Drawers have many faults.