Primary Voltage: 2.4kV / 11kV / 33kV / 34.5kV
Secondary Voltage: 480-240 / 240-120 or customized
Power Rating: 250 KVA
HV Tap Range: ±2×2.5% HV taps or others
Type: Conventional Type
Standards: IEEE, ANSI, NEMA, ASTM
Cooling Method: ONAN
Certificate: CE, ISO
The single-phase pole-mounted transformer has a simple structure and small size. It generally adopts a suspended installation method and can be installed on a single pole or double poles near the electrical load, which can shorten the low-voltage power supply radius. It is suitable for distributed load power supply methods and can operate in single-phase mode or be combined with three single-phase units for three-phase operation.
The 250 kVA Pole Mounted Transformer produced by CHBEB has been widely exported to the United States, Canada, Mexico, Southeast Asia, South America, and other regions.
Transformer Body
250 kVA Pole Mounted Transformer has core-type structure and shell-type structure. The core material can be amorphous alloy or silicon steel sheet, both adopting an open wound core mode.
Core type refers to a double-coil single-core structure. The core adopts a top-opening form, and the coil arrangement generally adopts a low-high structure.
Shell type refers to a single-coil double-core structure. The core mostly adopts a side-opening mode, and the coil arrangement generally adopts a low-high-low structure or low-high structure.
Core
250 kVA Pole Mounted Transformer core materials include amorphous alloy and silicon steel sheet. At present, silicon steel sheet cores are in greater demand. Amorphous alloy adopts a mold-forming annealing mode. Silicon steel sheet cores have two processing methods: one is the mold-forming annealing mode, and the other is the octagonal bending non-annealing mode. The annealing mode and octagonal bending mode each have advantages and disadvantages, and both can be adopted. Relatively speaking, the annealing mode has more stable performance.
Oil Tank
The oil tank of 250 kVA Pole Mounted Transformer is generally made into a cylindrical shape with 2–3 mm cold-rolled steel plate, and the tank cover is made of 3 mm steel plate. Since the tank cover requires mold processing, a common diameter should be selected as much as possible when designing the oil tank. The tank cover and barrel body can be connected by a hoop, or a pressing nail structure can be adopted. Upper and lower mounting lifting plates need to be welded on the barrel body according to standard requirements. The oil level is generally given as a 25° oil level inside the barrel body, and an oil level gauge can also be equipped according to requirements. An air gap is reserved at the top inside the oil tank, which can meet the volume change of transformer oil due to thermal expansion and contraction. According to performance requirements, radiators are equipped, which can be corrugated sheets or panel radiators.
In Western developed countries as well as Southeast Asia, North America, and South America, single-phase transformers are widely used as distribution transformers. In distribution networks with dispersed power supply, single-phase transformers have great advantages as distribution transformers. They can reduce the length of low-voltage distribution lines, reduce line losses, and improve power supply quality. The pole-mounted single-phase transformer produced by CHBEB adopts a high-efficiency energy-saving wound core structure design and a pole-mounted suspended installation method, with small size, low infrastructure investment, and reduced low-voltage power supply radius. It can reduce low-voltage line loss by more than 60%. It is suitable for rural power grids, remote mountainous areas, scattered villages, agricultural production, lighting and power electricity, and can also be used for pole-mounted distribution lines in railway and urban power grid energy-saving renovation projects.
| Item | Standard Value | Notes |
| Rated Capacity | 250 kVA | Apparent power; electromagnetic capacity = 250×(1-U₂/U₁) |
| Phase / Frequency | 3 Phase / 50 Hz / 60 Hz | 60 Hz for Philippines, North America and Southeast Asia export |
| Rated Primary Voltage | 11kV | Tap range: ±2×2.5%, 5-position off-load tap changer (NLTC) |
| Common Secondary Voltage | 6.6kV / 3.3kV / 0.415kV | 11kV/6.6kV is the most common distribution ratio |
| Vector Group | Yy0 / YNa0 | Star neutral point must be reliably grounded |
| Cooling Method | ONAN (ONAF forced air cooling optional) | ONAN standard for outdoor box-type substation and pole-mounted installation |
| Insulation Class | Class A oil-immersed insulation | Winding temperature rise ≤65K, top oil temperature rise ≤60K |
| Short-Circuit Impedance (Uk) | 4% | Unified standard impedance for small to medium capacity 250kVA |
| No-load Current | ≤0.55% | Standard limit for high-permeability cold-rolled silicon steel sheets |
| Noise (at 1m) | ≤55 dB | Residential area distribution noise reduction requirement |
| Operating Environment | Altitude ≤1000m, -25°C to +40°C | Enhanced insulation available for altitude >1000m |
| Tank Protection Rating | IP54 fully sealed corrugated oil tank | Rainproof, dustproof, resistant to coastal salt fog corrosion |
