Low-voltage power distribution mode
The low-voltage power distribution design of data centers refers to the power distribution scheme and product design with a frequency of 50 Hz and an AC voltage of 1 200 and below. The construction of low-voltage system first involves low-voltage electrical appliances, which usually refer to electrical appliances that work below 1 200 V AC or 1500 V DC, and play the role of protection, control, regulation, conversion and on-off in the circuit protection of power supply systems and electrical equipment.
The classification is described below.
1) Electrical appliances for power distribution protection: used in power grid systems, mainly referring to low-voltage fuses, low-voltage isolation appliances (knife switches, isolation switches, load switches, etc.), low-voltage circuit breakers (automatic switches), etc. The technical requirements are strong on-off current capability, good current limiting effect, good protection performance, good anti-electrodynamic force and good thermal resistance.
2) Control electrical appliances: used for power driving and automatic control systems, mainly contactors, starters and various control relays, main electrical appliances, etc. The technical requirements are corresponding conversion capacity, high operating frequency, long electrical life and mechanical life.
The low-voltage distribution system consists of distribution devices and distribution lines. The low-voltage distribution mode refers to the distribution mode of the low-voltage trunk line. There are three types of low-voltage power distribution: radial, trunk and chain.
1) Radial.
Radial is a distribution method in which power is supplied directly to the distribution box or load by the main distribution box. The advantage is that each load receives power independently, and once a fault occurs, it is only limited to itself without affecting other circuits, and the power supply reliability is high, the control is flexible, and it is easy to realize centralized control. The disadvantages are that there are many lines, the consumption of non-ferrous metals is large, and the flexibility of the system is poor. This power distribution mode is used for equipment with large capacity, equipment requiring centralized control, and important equipment distribution circuit requiring power supply reliability.
2) Trunk type.
Trunk type refers to the distribution mode that adopts a trunk connection between the main distribution box and the distribution box. The advantages are low investment cost, convenient construction, and easy expansion. The disadvantage is that when the trunk line fails, the impact range is large and the power supply reliability is poor. This power distribution method is often used in open-laid circuits, equipment with small equipment capacity, and equipment with low requirements for power supply reliability.
3) Chain. The chain type is to carry a plurality of electrical equipment or distribution boxes on a power supply trunk, and the trunk type is different in that the branch point of the line is in the electrical equipment or distribution box, that is, the power supply of the rear equipment is drawn from the terminal of the front equipment. The advantage is that there are no branch points on the line, which is suitable for pipe laying or cable line, saving non-ferrous metals. The disadvantage is that when the maintenance line or equipment or line fails, all the connected equipment will be powered off, and the reliability of power supply will be poor. This power distribution method is suitable for small-capacity equipment with low requirements for power supply reliability of dark-laid lines, and generally the equipment in series should not exceed 3 4 units, and the total capacity should not exceed 10 kw