30 kva Single phase transformer/ QIANLAI ELECTRIC
Application
The 30 kva single phase overhead transformer may be used alone for the supply of a single phase load or as one of three units in a bank for the supply of a three phase load. The unit may be direct mounted to a wooden or concrete pole, or cluster mounted on a pole for three phase use.
Our single phase overhead distribution transformer is commonly used in various places including rural areas, remote regions and scattered villages to provide high quality power supply for daily lighting, agricultural production and industrial plants. Aside from these, it is also suitable for the energy saving projects for railway and urban grid.
| Primary voltage | Secondary voltage | ||||||
| Rating (V) | BIL(kV) | 120V/240V 240V/480V 139V/277V 250V/500V | |||||
| 41600-48000 | 75 | ||||||
| 72000-12470 | 95 | ||||||
| 13200-14400 | 125 | ||||||
| 19920-22900 | 150 | ||||||
| 34500 | 200 | ||||||
| capacity (KVA) | primary Rating(KV) | Amorphous core | CRGO core | ||||
| No load loss(W) | Load loss(W) | No load loss(W) | Load loss(W) | ||||
| 3 | 13.8/7.967KV 13.2/7.62KV 11/6.35KV Or customizable | 8 | 45 | 9 | 45 | ||
| 5 | 8 | 75 | 19 | 75 | |||
| 10 | 12 | 120 | 36 | 120 | |||
| 15 | 15 | 195 | 50 | 195 | |||
| 25 | 18 | 290 | 80 | 290 | |||
| 37.5 | 30 | 360 | 105 | 360 | |||
| 50 | 32 | 500 | 135 | 500 | |||
| 75 | 45 | 650 | 190 | 650 | |||
| 100 | 50 | 850 | 210 | 850 | |||
| 167 | 65 | 1410 | 350 | 1410 | |||
Installation Specifications for 30 kva Single Phase Transformer
The installation of 30kVA single-phase pole-mounted transformers shall comply with GB 50147-2010, GB 50150-2016 and the typical design requirements of State Grid. The core requirements include prioritizing single-pole installation, complying with safety distance standards, ensuring reliable electrical connections, and implementing proper grounding and lightning protection measures. The complete implementation specifications are as follows:
- Foundation and Platform Installation (SinglePole Preferred for 30kVA Capacity)
Pole Selection and Erection
Select cement poles of 12m or longer. The buried depth of pole pits shall be ≥ 2m (1/6 of the pole length). The chassis shall be level, backfill shall be compacted in layers, and chuck plates or guy wires shall be installed to prevent tipping.
The distance from the lower edge of the platform crossarm to the ground shall be ≥ 3.4m, and the skew of the crossarm end shall be ≤ 20mm. The pole may be pre-inclined 13°–15° in the opposite direction of the transformer to enhance stability.
The platform shall be fixed with channel steel with a slope ≤ 1/100, and the conservator side shall be slightly elevated to facilitate oil drainage and the operation of the gas relay.
Transformer Fixation
Fix the transformer with special hoop clamps, supporting brackets and anti-vibration pads. For single-pole installation, auxiliary binding with galvanized iron wire is required to prevent tipping.
The inclination of the transformer body shall be ≤ 1/100. The high-voltage outlet terminals shall be arranged on the same side as the drop-out fuse for convenient operation and maintenance.
II.Electrical Connection and Insulation Requirements
Terminal Connections
- Copper alloy terminals shall be used for high-voltage bushings, which are tinned and coated with conductive paste, then fastened with bolts (U-bolts or J-bolts are prohibited).
- The tap changer shall be set to the rated voltage gear, locked after switching, and phase marks shall be made.
Insulation and Testing
- Measure insulation resistance before installation: high-voltage to ground ≥ 300MΩ, low-voltage to ground ≥ 10MΩ (tested with a 2500V megohmmeter at 25℃).
- The leads shall have consistent curvature without sharp bends. All joints shall be crimped firmly, and insulation covers shall be color-coded according to phase sequence (yellow for phase A, green for phase B, red for phase C).
III. Grounding and Lightning Protection
Grounding System
- The transformer casing, neutral point, lightning arrester, distribution box casing, etc., shall be jointly grounded. The grounding electrode shall be made of flat steel ≥ 50×5mm or round steel ≥ φ16mm, with a buried depth ≥ 0.6m.
- Welding requirements: for flat steel, welding length ≥ 2 times the width (double-sided welding); for round steel, welding length ≥ 6 times the diameter. Anti-corrosive asphalt paint shall be applied after welding.
- Grounding resistance standards: neutral point ≤ 4Ω, lightning protection grounding ≤ 10Ω. If the resistance is unqualified, add ground resistance reducing agent or extend the grounding electrode.
Lightning Protection Measures
- Install zinc oxide lightning arresters on the high-voltage side and surge protectors (SPD) on the low-voltage side to achieve multi-level protection.
- A live-line earthing ring shall be installed between the fuse and the lightning arrester to facilitate grounding during power outage maintenance.
