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Distribution boards for transformation points
They are used for network transformer points provided with power transformers of 250÷630 (1000) kVA, 20/0, 4 kV. They supply with electric energy the urban public buildings, commercial agents and street lighting.
Functions
- They allow the interruption of the general electric circuit and protect the transformer against malfunctions or overloads which can appear in the low voltage or street lighting network. This is made through a removable or fixed automatic breaker. In case a fixed breaker is used, a separator has to be included as well, in order to make visible the interruption of the circuit during interventions on the board
- They provide the interruption in case of defect on each phase of the electric circuit on low voltage outputs and of public lighting by burning out the safety fuses and provide the visible separation in order to protect the personnel by taking out safety fuses
- They provide electric energy supply for night time public lighting, the switch-on being made manually or automatically
Technical features:
| rated power: |
250 ÷ 630 (1000)kVA |
| thermal and usage rated current: |
360A ÷ 910 (1440)A |
| transformer current: |
400 ÷ 1000 (1500)/5A, class 0.5 |
| rated voltage: |
400/ 230 V a.c. |
| insulation voltage: |
690 V a.c. |
nominal frequency:
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50 Hz |
normal protection standard:
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IP 00 (open var.)
IP 20 (semi-closed var.)
IP 43 or IP 54 (closed var.) |
Component parts
- Metal cabinet Alfa-System in semi-closed and closed variants or metallic framework in opened variant, both variants are made up of modules
- Three-pole or four-pole automatic general breaker, removable or fixed
- Three-pole separator with nominal current equal to that of the general breaker (it is assembled when the breaker is fixed)
- Input electric energy three-phase metering unit
- Lighting point for public lighting provided with manual or automatic control
- Three-phase feeding columns made of: SIST type fuses or vertical three-pole sockets or vertical three-pole separators
- Power unit for public lighting
- Three-phase metering unit for counting the electrical energy used for public lighting
- Bridging unit for current secondary circuit (units and test plugs) for indirect metering
- 3 fuses LF – 25/6A on the voltage circuits of meters
- Terminal house, with connection terminals in null bar variants and main bars for input and output circuits
Operating conditions:
| Erection location: |
Indoors/outdoors |
| 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: |
Max. 100% at 25°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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Other information:
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