KBSG Mining Explosion-Proof Dry-Type Transformer
Applications and Operating Conditions
The KBSG mining explosion-proof dry-type transformer is designed for underground coal mines where methane gas, coal dust and explosion hazards may be present. It is mainly used as a power distribution device for fully mechanized mining equipment.
The transformer is suitable for long-term continuous operation at its rated capacity under the following conditions:
- Installation altitude: Not more than 2,000 meters
- Maximum ambient temperature: +40°C
- Maximum relative air humidity: 95% at +25°C
- Installation environment: Free from strong impact and vibration
- Maximum inclination from the vertical position: 15 degrees
- Surrounding atmosphere: Free from gases or vapors that may corrode metal or damage insulation
- Installation location: Free from dripping water
Structural Overview
The KBSG mining explosion-proof dry-type transformer consists of an enclosure, enclosure cover, core assembly, insulation assembly, high-voltage leads, low-voltage leads and a rail-mounted trolley.
Explosion-Proof Enclosure
The transformer enclosure adopts a top-opening flameproof structure. Four small lifting lugs are installed on the cover to assist with cover removal and lifting.
Corrugated steel plates are installed on both sides of the enclosure, while the bottom is made from thick steel plate.
High- and low-voltage connection flanges are provided for connecting the transformer to the corresponding high- and low-voltage switchgear.
Four large lifting lugs are installed on the enclosure for lifting the complete transformer. Grounding bolts and grounding symbols are welded at both ends of the enclosure for connection to the external grounding system.
High- and low-voltage interlocking wires and temperature control wires are installed inside the transformer and connected to the corresponding switchgear.
The temperature control system uses a PT100 platinum resistance sensor or a temperature relay. When the internal transformer temperature becomes too high, the system sends an over-temperature signal.
Core Assembly
The core assembly consists of the transformer core, clamps and insulating components.
The core is made from high-quality cold-rolled, grain-oriented silicon steel sheets. It adopts a multi-step, fully mitred three-joint laminated structure to reduce no-load loss and no-load current.
The cut surfaces of the core sheets are coated with anti-rust liquid. The core columns and lower yoke surfaces are also coated with high-temperature, moisture-resistant and rust-resistant paint.
The clamps are made from channel steel. The upper and lower sections are tightened with tie rods, and measures are adopted to prevent relative movement between the core and clamps.
The core insulation components are made from high-quality insulating materials.
Insulation and Coil Assembly
The insulation assembly includes the main longitudinal insulation, high- and low-voltage coils and coil compression structure.
The main longitudinal insulation uses high-quality insulating materials. The high- and low-voltage coils adopt a tightly wound structure to improve their mechanical strength.
Both windings use oxygen-free copper conductors wrapped with Class C insulating paper. This provides a uniform electric field around the coils and helps reduce partial discharge.
The coils are compressed with pressure studs and ceramic pressure blocks, with suitable measures taken to prevent loosening.
The high-voltage leads use cables, while the low-voltage leads use cables or copper busbars.
The creepage distances and air clearances exceed the requirements of GB 3836.3-2000. Under normal operating conditions, the structure does not produce sparks, electric arcs or dangerous temperatures, helping ensure safe and reliable operation.
Rail-Mounted Trolley
The trolley is bolted to the bottom of the transformer enclosure and can be removed when required.
Available trolley track gauges are 900 mm and 600 mm.
Manufacturing, Installation and Acceptance Standards
The transformer is designed, manufactured and tested according to current national standards, electric power industry standards and other applicable technical requirements, including:
- GB/T 16927.1-1997 — High-Voltage Test Techniques, Part 1: General Test Requirements
- GB/T 16927.2-1997 — High-Voltage Test Techniques, Part 2: Measuring Systems
- GB/T 5582-1993 — Pollution Levels for External Insulation of High-Voltage Power Equipment
- GB 10237-1988 — Insulation Levels, Insulation Tests and External Clearances for Power Transformers
- GB 3836.1-2000 — Electrical Equipment for Explosive Gas Atmospheres: General Requirements
- GB 3836.2-2000 — Electrical Equipment for Explosive Gas Atmospheres: Flameproof Enclosure “d”
- GB 3836.3-2000 — Electrical Equipment for Explosive Gas Atmospheres: Increased Safety “e”
- GB 6450-1986 — Dry-Type Power Transformers
- GB 8286-2005 — Flameproof Mobile Substations for Mining
