Siemens 35kV 4000-20000kVA Encapsulated On Load Tap Changer Transformer Supplier

The 35kV resin cast on-load tap-changer power transformer delivers reliable voltage regulation and fire-safe operation for industrial distribution networks and renewable energy systems. Featuring a 4000 to 20000 kVA capacity range and ±4 x 2.5% live regulation, this dry-type unit ensures stable power delivery under fluctuating loads. Beijing Zhongping Technology supports regional engineering projects by supplying these robust transformers with comprehensive pre-shipment testing.

Industrial power distribution frequently suffers from voltage instability, network harmonics, and space constraints that challenge traditional oil-filled transformers. This 35kV cast-resin power transformer addresses these challenges through advanced vacuum-cast foil winding technology and a non-flammable, oil-free architectural design. The high-voltage system handles 35 to 38.5 kV inputs, while the low-voltage side adapts to 6 through 10.5 kV requirements with Dyn11 or Yd11 vector connections. By integrating an on-load tap changer, the unit modifies turns ratio dynamically under full load conditions without disrupting downstream operations. This mechanism optimizes power flow across heavy industrial plants, utility sub-stations, and renewable generation sites where consistent voltage profiles are mandatory.

Technical Specifications

Rated Voltage HV: 35 kV - 38.5 kV @ 50 Hz / 60 Hz

Rated Voltage LV: 6 kV - 10.5 kV @ 50 Hz / 60 Hz

Capacity Range: 4000 kVA - 20000 kVA @ Continuous Operation

On-Load Voltage Regulation: ±4 x 2.5% @ Live Load Conditions

Vector Group: Dyn11 / Yd11 @ Standard Configuration

Short-Circuit Impedance: 8% - 11% @ Rated Tap

Cooling Method: AN / AF @ Natural Air or Forced Air

Protection Class: IP00 - IP23 @ Enclosure Dependent

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

Temperature Rise: 100 K @ Average Winding Rise

Product Overview and Key Features

This unit represents a state-of-the-art cast-resin dry-type power transformer engineered for high-performance indoor and semi-outdoor primary distribution. It operates safely within medium-voltage utility infrastructures, large manufacturing facilities, and utility-scale solar or wind power integration hubs. The architecture eliminates liquid dielectrics entirely, removing explosion risks and toxic fluid containment requirements.

Vacuum-cast epoxy resin encapsulation protects the conductor windings against severe moisture, chemical pollution, and aggressive industrial airborne particulates. The foil winding geometry significantly enhances short-circuit mechanical stability by distributing electromagnetic axial forces uniformly across the coil height. Furthermore, low-loss grain-oriented silicon steel cores minimize core excitation losses, improving overall energy efficiency during prolonged operational cycles.

The integrated on-load tap changer allows seamless voltage adjustments under active load conditions, protecting sensitive downstream manufacturing machinery from grid sag. Natural air cooling maintains thermal equilibrium, while optional forced-air cooling fans boost capacity limits during peak operational demands. Low acoustic emission profiles allow facility managers to position the transformer closer to load centers, reducing secondary cable runs and distribution copper losses.

Applications and Selection Guide

Industrial facilities, utility substations, and large-scale renewable generation installations benefit substantially from this transformer's high thermal capacity and dynamic regulation. Data centers and hospitals prioritize its fire-safe, oil-free composition to satisfy strict safety regulations near human-occupied zones. Renewable energy sites utilize its precise voltage matching capabilities to stabilize variable power output before grid injection.

The selection workflow begins by verifying the primary system voltage and required apparent power capacity within the 4000 to 20000 kVA band. Next, engineers evaluate environmental conditions, determining whether standard IP00 open chassis or protective IP21 to IP23 enclosures are required. Voltage regulation parameters must match upstream utility fluctuation ranges to ensure the ±4 x 2.5% tap range provides adequate compensation. Finally, specify auxiliary monitoring features such as PT100 temperature sensors and digital controllers for comprehensive SCADA integration.

Installation and Compliance

Mechanical installation requires a level concrete foundation, utilizing structural base channels or directional swivel rollers for precise positioning. High-voltage connections utilize either conventional terminal studs or screened separable connectors, while low-voltage outputs interface via flexible copper busbars to isolate thermal expansion stress. All metallic enclosures, core frames, and neutral points must tie securely to the facility earth grid in compliance with relevant electrical safety codes.

Embedded PT100 resistance temperature detectors inside the low-voltage windings link directly to a digital control unit, triggering alarm and trip sequences if thermal limits approach threshold. Control wiring for tap-changer motors and temperature relays must use shielded twisted-pair cables routed through separate metal conduits away from high-power circuits. This unit complies with rigorous international manufacturing and safety standards, undergoing routine factory acceptance tests including partial discharge measurement, lightning impulse tests, and thermal run evaluations.

Selection Guidance and Alternative Options

Selecting the appropriate transformer variant involves balancing load profiles, ambient temperature parameters, and spatial constraints within existing switchgear rooms. Beijing Zhongping Technology provides expert technical guidance, helping engineers cross-reference specifications and secure matching distribution assets for regional projects. Alternative configurations within this product family include dual low-voltage output windings and specialized marine-grade corrosion-resistant frames for offshore platforms.

Frequently Asked Questions (FAQ)

1. What are the stock availability and delivery timelines for this transformer series?

Beijing Zhongping Technology maintains robust regional logistics channels to supply standard units efficiently, minimizing project downtime compared to overseas manufacturing lead times. Contact our engineering sales team for immediate stock status verification on specific kVA ratings.

2. What warranty coverage and RMA procedures apply to these units?

Every transformer is backed by a comprehensive 12-month operational warranty supported by rigorous factory testing protocols. In the unlikely event of a technical anomaly, local support teams coordinate rapid diagnostic and replacement assistance.

3. What are the functional differences and selection criteria between copper and aluminum windings?

Copper windings offer higher electrical conductivity and mechanical tensile strength, resulting in a more compact physical footprint and slightly lower load losses. Aluminum windings provide a cost-effective alternative for installations where physical space constraints are flexible and weight allowances permit larger core dimensions.

4. Can this dry-type transformer be installed outdoors?

The baseline transformer features an IP00 rating requiring an indoor enclosure or substation housing to protect against weather elements. When fitted with a specialized weatherproof enclosure rated up to IP23 or higher, it accommodates sheltered outdoor deployment.

5. What is the overload capacity profile under emergency operational conditions?

The cast-resin structure supports short-term emergency overloads in accordance with standard loading guides for dry-type transformers, provided ambient temperatures remain within acceptable design limits. Extended overloads require active cooling activation via auxiliary fan packages to prevent accelerated thermal insulation aging.

6. What routine maintenance is required for this oil-free transformer design?

The hermetically sealed resin encapsulation eliminates fluid testing, oil filtration, and gasket seal replacements typical of liquid-filled units. Routine upkeep is limited to periodic visual inspections of dust accumulation, terminal torque checks, and operational testing of thermal monitoring sensors.

7. How does the on-load tap changer operate, and what are its regulation limits?

The integrated on-load tap changer adjusts transformer turns ratio dynamically under live load conditions to maintain stable secondary voltage. It provides a total regulation range of ±4 x 2.5%, executed via an automated motor-drive control panel linked to voltage-sensing relays.

8. What compliance standards govern the acoustic noise emissions of these units?

Acoustic performance complies strictly with international NEMA and IEC standards for dry-type transformers. The low-noise core construction ensures sound pressure levels remain well within threshold limits suitable for noise-sensitive commercial and institutional environments.