Design issues of 160KW frequency conversion cabinet
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This post was last edited by A Bai_ugUmK on 2023-12-8 at 10:18. I’d like to ask the experts here. 1. Currently, there’s a 160KW variable-frequency induced draft fan that requires a control cabinet to be made. I plan to build a GGD cabinet. The location of the cabinet will be approximately 200 meters from the site. A Schneider ATV610 series inverter with a capacity of 160 KW, along with outlet filters, will be used. Dual-cable power supply is planned, using two cables of 3X95+1X50 gauge. On the motor side, there should be two power inlet ports. What about on the frequency converter side? Are two cables combined together or are there two ports? I have previously only worked on explosion-proof cabinets with capacities of a few dozen KW; I have little experience with non-explosion-proof cabinets of such high power, as well as those equipped with frequency converters. Ask everyone for their opinions. 2. It is also planned to build a power distribution cabinet with a capacity of around 650 KW; the busbars will receive power, and these busbars will supply power to the 160 KW frequency converter cabinet mentioned in question 1, while the remaining cables will be used to supply power to the cabinets/motors on site. Can GGDs also be used for distribution cabinets? Is this a viable way for power distribution? I’ve never made a drawer cabinet. 3. If it is a motor with two power inputs, then one contactor (soft starter) is used, with the two cables connected in parallel ； It’s still two relays; two cables go into each of the two contactors (for soft start). I haven’t worked on motors with dual power supplies yet, so I hope everyone can offer some guidance. 4. The total power of all motors in one cabinet is 40KW. In this case, should the power supply for this cabinet be calculated based on 40KW, or should a margin be added? If so, how much? 20%?
1. Design issues for the frequency conversion cabinet: For a 160KW frequency conversion exhaust fan, using Schneider ATV610 series frequency converters along with outlet filters is a suitable choice. Regarding the dual-cable power supply you mentioned, the selection of cables typically requires consideration of factors such as current level, cable length, and voltage drop. If calculations show that two 3X95+1X50 cables can meet the power supply requirements (taking factors such as voltage drop into account), then they can be used. At the motor end, if the motor is designed with two inlet ports, two cables are connected to each port respectively. On the inverter side, whether to connect in parallel depends on the design of the inverter’s input terminals. If the inverter’s input terminals can handle such a high current and are designed with two separate input terminals, they can be connected separately. If there is only one incoming terminal, it is usually necessary to connect two cables in parallel (provided that the terminal can safely handle the current resulting from this parallel connection). 2. Design issues of the distribution cabinet: It is feasible to use GGD distribution cabinets to house the busbars and supply power to a 650KW load, provided that the design of these GGD cabinets meets the required current load and safety standards. The busbar size and rated current need to be determined based on the total load, to ensure safe power supply to all loads, including the 160KW frequency converter cabinet. Regarding the design inside the distribution cabinet, multiple cable feeds can be provided by setting up different branch protections; each branch should be equipped with a suitable circuit breaker or fuse to protect the circuit. A drawer cabinet is an optional design suitable for situations where frequent operation is required or where better isolation and protection inside the cabinet are desired, but its design and cost are more complex. 3. Issues with motor contactors (soft starters) for two-wire motors: For motors with two wires, one contactor (soft starter) is usually sufficient, as the purpose is to control the way the motor starts, rather than to provide multiple power supply paths. Connecting two cables in parallel to the same contactor can reduce the starting current when starting the motor, thereby minimizing the impact on the power grid. However, if the motor is indeed designed with dual power inputs and you want two separate power supply paths, then two contactors can be used, with each cable connected to a different contactor. This design allows for greater flexibility and redundancy, but it also increases control complexity and cost. In practical applications, careful consideration should be given to the reliability, safety, and cost-effectiveness of the design, and the design should be carried out in accordance with the manufacturer’s instructions for motors and frequency converters as well as relevant electrical standards. If you have questions regarding electrical design and safety, it is best to consult an experienced electrical engineer or a professional power company. .
The frequency conversion cabinet and the power distribution cabinet are installed side by side, close to each other
For item 1, when the frequency conversion motor is more than 200 meters away, it is recommended to use a dedicated frequency conversion cable 2 (3*95+3*35). It’s fine that the motor side has two cable entrances (a single cable entrance would require too thick cables, making it difficult to operate the explosion-proof motor); then why are there still doubts regarding the wiring on the inverter side? It’s just splitting one cable into two; isn’t it the same? Regarding point 2, why doesn’t this work? As long as your busbar has sufficient capacity and the circuit breakers in the cabinet meet the requirements, how many can be connected? It seems that there is currently no standard specifying how many KW cannot be connected. Regarding point 3, this question shouldn’t even be asked. With the exception of a few voltage-reduction starting circuits (such as star-delta, autotransformer, etc.), it is correct to connect a motor to a single contactor (for soft start or frequency conversion). Of course, soft starters with external bypasses are not excluded here. To be honest, this still depends on the circumstances; there’s no fixed pattern. But I have yet to see a configuration where a motor that does not start under reduced voltage is connected to two contactors (for soft starting).