Key Points of Cold Storage Power Distribution Design | Cable Selection, Contactors, Air Switches, Grounding, and Computer Room Heat Dissipation
Cold storage belongs to continuous load equipment, with high starting current for compressors. The cable current carrying capacity and laying method in low-temperature environments are different from ordinary power distribution, and the power distribution is too small, which is prone to heating and tripping.
Three phase compressor cables are selected by amplifying one level according to the rated current, and then amplifying one level for long-distance and high-temperature environments in the machine room; Copper core cables are preferred, and aluminum wires with high voltage drop are not recommended.
Contactor capacity: Select according to the rated current of the compressor at 1.25 times or more, frequently start and stop parallel units, and then amplify the capacity to avoid contact erosion and phase loss.
Each compressor has an independent air switch and independent grounding, with a grounding resistance of ≤ 4 Ω; The compressor casing, condenser frame, and electrical control box are all reliably grounded to prevent electrical leakage.
The electrical control box cannot be placed tightly against the condenser and compressor, and the high temperature in the machine room leads to poor heat dissipation of the frequency converter and contactor inside the electrical control, resulting in an increased failure rate.
The Xitelide electronic control has built-in high temperature protection. If the temperature in the computer room exceeds 40 ℃, the heat dissipation of the electronic control will deteriorate. It is recommended to install exhaust fans in the computer room to control the temperature to ≤ 35 ℃.
Many engineering power distribution projects only look at the rated current on the nameplate, ignoring the starting impulse current. If the air switch is selected too small, it will trip as soon as it is turned on, repeatedly starting and stopping the impulse compressor.
The output end of the frequency conversion unit should be equipped with a dedicated frequency conversion cable, with the shielding layer grounded to reduce harmonic interference and avoid sensor signal drift and false alarms.
Overseas foreign trade projects experience significant voltage fluctuations, with a larger reserved margin for power distribution. At the same time, surge protectors are installed to prevent lightning strikes and voltage spikes from damaging the controller in the power grid.
The position where the cable passes through the storage plate must be sealed with a vapor barrier, and no gaps should be left directly. The gaps will continue to leak cold and condense, and the cable sheath will accelerate aging.
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FAQ
What is the recommended temperature control for the cold storage room? ≤ 35 ℃.
2. Requirements for grounding resistance of compressor? ≤ 4 Ω.
How to choose the capacity of the contactor? Rated current of 1.25 times or more, frequent start stop and add one gear.
What cables are used for variable frequency compressors? Specialized shielded variable frequency cable.
5. What should be done when cables pass through the storage board? Sealed and vapor proof to prevent cold leakage and condensation.
Why not recommend aluminum wire? The voltage drop of the line is large and the operation is unstable.
What is the increase in power distribution in areas with unstable voltage? Surge protective device.
