Size classification of small power distribution unit (spdu):

The size of the small power distribution unit (spdu) itself can be divided into three types according to the size classification: the size of the primary small power distribution unit (spdu) is generally 0.8mx0 6mX2. 2m； The size of secondary small power distribution unit (spdu) is generally 1mx1 2m； The size of three-level small power distribution unit (spdu) is generally 500mmx600mm.

By use classification:

1. Fixed panel type, often referred to as switch board or distribution panel. It is an open small power distribution unit (spdu) with panel blocking. The front has protective effect, and the back and side can still touch the live parts. The protection level is low. It can only be used for industrial and mining enterprises with low requirements for power supply continuity and reliability for centralized power supply in the substation.

2. Power lighting small power distribution unit (spdu). Mostly closed vertical installation. The degree of protection of the enclosure varies according to the use occasion. They are mainly used as power distribution devices at the production site of industrial and mining enterprises.

3. Protective closed type, all sides are closed except the installation surface. The switch, protection, monitoring and control and other electrical components of the small power distribution unit (spdu) are installed in a closed shell made of steel or insulating materials, which can be reliably installed on or off the wall.

4. Drawer type. The closed shell of this kind of small power distribution unit (spdu) is made of steel plate, and the electrical components of the incoming and outgoing circuit are installed in the withdrawable drawer to form a functional unit that can complete a certain type of power supply task. Functional units are separated from buses or cables by grounded metal plates or functional plates made of plastic to form three areas of buses, functional units and cables.

So how to choose the size of small power distribution unit (spdu)?

1. When the electric box is only a lighting electric box or small power, and the incoming line is less than 10 square meters, if the number of switch bits is less than 20 bits, the switch width plus 20mm on each side is the width of the electric box, the height is the switch height plus 40mm, and the depth is the switch Zui large depth plus 10mm.

2. When the electric box is only a lighting electric box or a small power, and the incoming line is less than 10 square meters, if the number of switch bits is greater than 20, the electric box needs to be arranged as two rows of switches. The switch width plus 40mm on each side is the width of the electric box, the height is the switch height plus 40mm, and the depth is the switch depth plus 10mm.

3. When the electric box is only a lighting electric box or small power, and the incoming line is less than 10 square meters, if the incoming line switch needs a separate row, the switch width plus 20mm on each side is the width of the electric box, the height is the switch height plus the incoming line switch height plus 40 mm, and the depth is the switch depth plus 10 mm.

4. When the power box is a power box or a power lighting box, the algorithm is basically the same as above. However, when the incoming line is greater than 10 square meters, the bending radius of the incoming line shall be considered, and sufficient space shall be reserved for the incoming line at the primary wiring terminal. When the switches are arranged in two rows, the wiring layout of the switches shall be considered.