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Three-phase low voltage selective box
It is used in low voltage distribution network to provide the selectiveness and the sensitivity of the protections against the short-circuit currents, downward the erection point, till the end of the line and its derivations.
Functions:
- It visibly separates the power circuit (three-phase) in order to protect the operating personnel, through the removal of safety fuses.
Technical features:
| Thermal and usage rated current : |
Max.250A; |
| Rated power: |
400/230 Vc.a; |
| Rated insulation voltage: |
690 Vc.a; |
| Rated frequency: |
50Hz÷2% |
| Protection standard: |
IP 54. |
Components parts
- Metallic or polycarbonate box which provides the normal IP 54 protection standard
- Three-phase supplying column provided with SIST type fuses
- Pressure gaskets or fittings for input/output supplying cables
- Fastening accessories on poles
Operating conditions:
| Erection location: |
Outdoor |
| Climate group: |
WDr/CT (moderate climate: hot dry / cold temperate) |
| Environment ambient temperature range during operation: |
-25 ÷ 40°C |
| Environment ambient temperature range during transportation, storing and erection: |
-40÷50°C |
| Average ambient temperature in 24 hours: |
35°C |
| Air relative humidity: |
90% la 20°C |
| Maximum altitude: |
2000 m |
| Pollution degree: |
3 |
| Over-voltage category: |
Category III |
| Electro-magnetic mediums: |
Environment A |
| Life span: |
25 years |
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Erection and connection
- The selective boxes are mounted at a certain height on poles or at the pole base, the attachment and fastening are made with clamps and screws
- The connection of the cables is made with cable clips; the input and output of the cables being provided with pressure gaskets and suitable fittings
- As the boxes are mounted outdoors, the access doors have special locks to prevent the access of unauthorized personnel
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