Siemens 35kV 200-2500kVA Three Phase Fire Resistant Transformer Cast Resin Dry Type

This 35kV cast-resin distribution transformer delivers a rated capacity of 200–2500 kVA with reliable dry-type operation. Engineered for medium-voltage indoor distribution, it incorporates a fire-safe, oil-free design to minimize environmental hazards.

The continuous expansion of urban industrial facilities and dense commercial complexes creates severe pressure on medium-voltage power distribution networks, frequently resulting in spatial constraints and strict fire safety demands. Traditional oil-immersed transformers present inherent fire hazards and require extensive containment infrastructure, making them unsuitable for indoor or subterranean installation. This 35kV cast-resin dry-type distribution transformer addresses these vulnerabilities by utilizing a vacuum-cast epoxy resin winding architecture that eliminates combustible insulating fluids entirely. Operating at system voltages with high-voltage tappings at 35, 36, 37, and 38.5 kV and a low-voltage output of 0.4 kV, the unit integrates advanced foil winding technology to optimize electromagnetic distribution. This design significantly improves short-circuit mechanical strength while maintaining a compact footprint for seamless integration into package substations and confined utility rooms.

Product Overview and Key Features

This product is a class of 35kV cast-resin dry-type distribution transformers designed specifically for safe, efficient indoor medium-voltage power distribution. It accommodates capacity ratings from 200 to 2500 kVA, making it highly versatile for commercial buildings, industrial plants, and utility infrastructure.

Vacuum-cast epoxy resin windings provide superior moisture resistance, crack prevention, and exceptionally low partial discharge levels. The foil winding construction improves mechanical stability under short-circuit conditions by uniformly distributing axial forces. The oil-free, fire-safe configuration eliminates fire risks and environmental contamination, allowing installation directly adjacent to load centers.

Low-loss performance characteristics reduce operational energy waste, while optimized core and coil geometries minimize acoustic noise for noise-sensitive environments. Optional intelligent monitoring packages incorporating PT100 temperature sensors and RS485 communication ports enable real-time thermal tracking and supervisory control integration.

The core utilizes high-grade grain-oriented silicon steel sheets assembled with precision step-lap joints to minimize core losses and excitation current. High-voltage and low-voltage windings are structured using high-purity copper or aluminum conductors wrapped with insulating foil. Natural air cooling (AN) is standard, with forced air cooling (AF) available as an upgrade to enhance short-term overload capacity.

Technical Specifications

Rated Voltage HV: 35 kV @ 50 Hz

Rated Voltage LV: 0.4 kV @ 50 Hz

Capacity Range: 200 - 2500 kVA @ Continuous Operation

HV Tappings: 35 / 36 / 37 / 38.5 kV @ Off-Circuit Tap Changer

Vector Group: Dyn11 / Yyn0 @ Standard Configuration

Loss Level: 13-type Low-Loss Level @ Rated Load

Conductor Material: Copper or Aluminum @ Foil Winding

Cooling Method: AN / AF @ Natural or Forced Air

Insulation Class: Class F / H @ 155°C / 180°C Temperature Index

Enclosure Protection: IP00 / IP20 / IP23 @ Indoor Installation

Winding Encapsulation: Vacuum Pressure Casting Epoxy Resin @ 100% Solid Content

Partial Discharge: Less than 10 pC @ 1.3 Um

Applications and Selection Guide

This transformer is engineered for medium-voltage power distribution in environments demanding high fire safety and compact equipment footprints. Typical application scenarios include high-rise commercial complexes, hospitals, data centers, underground transit stations, and industrial manufacturing plants. In these environments, selecting the appropriate unit requires evaluating specific spatial constraints, acoustic emission limits, and local building fire codes.

The selection procedure follows a structured engineering path starting with the determination of system voltage parameters and required apparent power capacity. Next, buyers must specify the appropriate energy-efficiency tier, such as the 13-type low-loss level, to align with facility operational expenditure targets. Enclosure protection classes must be chosen based on environmental exposure, ranging from open-frame IP00 for dedicated electrical rooms to IP20 or IP23 for inhabited spaces. Optional customizations, including dual low-voltage outputs, specialized enclosures, or embedded temperature controllers, can be integrated to meet specialized operational demands.

Installation and Compliance

Proper mechanical placement requires anchoring the transformer base firmly to a level concrete foundation, utilizing anti-vibration pads or steerable rollers to isolate structural resonance. Enclosure selection must correspond to environmental exposure, typically utilizing IP20 or IP21 for standard indoor substations to prevent ingress of solid foreign objects. High-voltage connections are executed via specialized terminal bushings or separable connectors, while low-voltage terminations utilize flexible copper busbars to accommodate thermal expansion.

Cable routing requires separating medium-voltage power lines from low-voltage control and temperature monitoring wiring to prevent electromagnetic interference. Low-voltage busbars must feature flexible expansion joints to mitigate thermal stress and dynamic mechanical vibration during load fluctuations. The main iron core, transformer frame, and metallic enclosure must maintain low-impedance grounding paths connected to the facility main earth grid in compliance with applicable safety codes.

The transformer design and manufacturing processes comply with relevant international and national standards covering dry-type power transformers. Type tests include lightning impulse voltage tests, temperature rise tests, and short-circuit withstand evaluations to guarantee operational safety. Routine factory testing verifies insulation resistance, transformation ratio, vector group verification, and no-load loss measurements prior to dispatch.

Selection Guidance and Alternative Options

Engineering teams specifying medium-voltage dry-type equipment must balance capacity ratings, impedance voltages, and physical dimensions to match existing switchgear configurations. When specific project footprints or specialized electrical parameters require customized engineering, local technical support becomes essential. Beijing Zhongping Technology provides professional engineering consultation and cross-reference selection services to help match alternative ratings or retrofitting requirements. Their technical team assists with component verification and localized availability to streamline procurement workflows.

Frequently Asked Questions (FAQ)

1. Q: What are the current stock availability and delivery timelines for standard capacity ratings?

A: Standard 35kV cast-resin transformers spanning 200 to 2500 kVA are maintained in regional distribution inventory to minimize lead times. Beijing Zhongping Technology coordinates rapid dispatch schedules to circumvent lengthy manufacturing backlogs.

2. Q: What warranty terms and after-sales support apply to these dry-type distribution transformers?

A: Units are backed by a comprehensive factory warranty covering manufacturing defects and material integrity. Beijing Zhongping Technology offers localized technical assistance, diagnostic support, and expedited replacement coordination.

3. Q: What are the primary performance differences and selection criteria between copper and aluminum windings?

A: Copper windings offer higher electrical conductivity and mechanical tensile strength, resulting in a more compact transformer footprint for restricted spaces. Aluminum windings provide a lighter structural weight and a cost-effective alternative for installations where space limitations are less restrictive.

4. Q: Can this cast-resin dry-type transformer be installed in outdoor environments?

A: Standard configurations are rated for indoor installation within protective electrical rooms or switchgear enclosures meeting IP00, IP20, or IP23 standards. Outdoor deployment requires a specialized weatherproof enclosure rated IP54 or higher to protect against precipitation and direct solar radiation.

5. Q: What is the short-term overload capacity of this transformer under elevated ambient conditions?

A: The epoxy resin cast structure possesses strong thermal inertia, allowing temporary overloads in accordance with standard loading guides for dry-type transformers. Continuous operation beyond rated capacity requires adequate ambient ventilation or the implementation of forced air cooling fans.

6. Q: What routine maintenance is required for an oil-free cast-resin transformer?

A: The absence of insulating oil eliminates the need for fluid sampling, dielectric filtration, or hermetic seal inspections. Routine maintenance is limited to periodic dust removal from winding surfaces and terminal inspections in accordance with facility environmental conditions.

7. Q: How does the acoustic noise level perform in noise-sensitive locations like hospitals or commercial buildings?

A: Core and coil assemblies are designed with optimized magnetic flux densities and isolated dampening supports to maintain low decibel emission levels. This makes the unit suitable for installation near inhabited areas without requiring heavy acoustic enclosures.

8. Q: What is the operational function of the 13-type low-loss designation?

A: The 13-type low-loss designation indicates optimized core steel utilization and winding geometry designed to reduce no-load and load power dissipation. This efficiency level lowers operational electricity consumption and reduces life-cycle heat dissipation within the substation room.

9. Q: Can the off-circuit tap changer be adjusted while the transformer is energized?

A: No, the high-voltage tappings at 35, 36, 37, and 38.5 kV are managed via an off-circuit tap link that must only be adjusted when the transformer is completely de-energized and isolated. Attempting tap adjustments under load creates severe electrical arc hazards.

10. Q: What monitoring signals and protection interfaces are included with the temperature controller?

A: The unit features embedded PT100 resistance temperature detectors within the low-voltage winding blocks linked to a digital temperature controller. The system provides programmable alarm outputs for elevated temperature stages and automatic trip signals to upstream circuit breakers.