CEMarked CEMarked Explore our certified manufacturing line: from low-zero-sequence earthing transformers and high-efficiency distribution units to motor control assemblies and harmonic mitigation reactors engineered for European utilities.
In modern three-phase medium-voltage distribution systems, network reliability and insulation coordination depend fundamentally on the earthing regime. Across Romania, the continuous expansion of renewable energy generation—anchored by massive wind turbine arrays in the Dobrogea plateau and expansive photovoltaic parks across Muntenia, Oltenia, and the Western Plain—has transformed grid operational dynamics. Medium-voltage networks operating at ungrounded (isolated) or delta-connected secondary distribution systems (typically 20 kV or 33 kV) lack an inherent neutral point. Without a designated neutral, single phase-to-ground faults cannot create a defined return loop, allowing dangerous transient overvoltages, capacitive charging current escalation, and destructive arcing ground phenomena to degrade cable insulation and substation switchgear.
As one of the world's premier transformer manufacturers and specialized exporters, our manufacturing facility engineers and exports heavy-duty Grounding Transformers (Earthing Transformers) built to provide an artificial, low-impedance neutral point for isolated or delta-connected networks throughout Romania. Fully compliant with international standard IEC 60076-6, European Harmonization Documents (CENELEC HD 637 S1), and the rigorous Technical Grid Code established by the Romanian National Power Grid Company (Transelectrica), our units stabilize system neutral-to-ground potentials, enable instantaneous ground fault detection via zero-sequence protective relays, and mitigate catastrophic line flashovers.
A grounding transformer must deliver high magnetic permeability under balanced steady-state operating conditions while presenting an exceptionally low zero-sequence impedance ($Z_0$) during asymmetrical ground faults. We engineer two core topologies customized for Romanian substation engineering specifications:
1. Zigzag (ZN / ZNyn11) Interconnected Star Winding: This is the industry standard for grounding applications. Each phase leg consists of two equal winding sections wound in opposite directions on separate core limbs. During normal symmetrical operation, the opposing magnetomotive forces (MMF) cancel each other out, drawing negligible magnetizing excitation current. When a phase-to-ground fault occurs, the zero-sequence fault current divides equally among all three phases and circulates in the interconnected windings in magnetic opposition. This design yields minimal zero-sequence impedance ($Z_0 \approx Z_1$), allowing rapid flow of fault current directly to the ground point without saturating the electrical steel core. Units equipped with a secondary auxiliary star winding (ZNyn11) concurrently supply low-voltage auxiliary substation power (typically 400V/230V, 50 Hz), powering essential SCADA, heating, and cooling circuits.
2. Wye-Delta Grounding Bank (YNd11): Engineered primarily when higher secondary auxiliary load demands (500 kVA to 2500 kVA) are combined with neutral grounding duties. The primary wye-connected winding has its neutral solidly or impedance-grounded, while the closed-delta secondary winding acts as a low-impedance circulatory path for zero-sequence currents and suppresses third-harmonic flux distortion.
Our grounding transformers are custom-tailored to the operational fault levels, short-circuit durations, and ambient climatic conditions of Romanian distribution networks operated by Distribuție Energie Electrică Romania (DEER), Rețele Electrice (former E-Distribuție), and Delgaz Grid.
| Electrical Parameter | Oil-Immersed Standard (ONAN / KNAN) | Cast Resin Dry-Type (AN / AF) | Romanian Grid Compliance Standard |
|---|---|---|---|
| Nominal System Voltage ($U_n$) | 6.3 kV, 10.5 kV, 15 kV, 20 kV, 33 kV, 35 kV | 10 kV, 20 kV, 30 kV | Transelectrica / ANRE Distribution Grid Code |
| Highest Voltage for Equipment ($U_m$) | Up to 36 kV / 40.5 kV | Up to 24 kV / 36 kV | IEC 60076-3 / SR EN 60076 |
| Rated Short-Time Neutral Current ($I_n$) | 100 A to 3000 A (Tailored to NGR / Peterson Coil) | 100 A to 1500 A | IEC 60076-6 Cl. 8.2 Short-Circuit Thermal Limits |
| Fault Duration Capability | 5 seconds, 10 seconds, 30 seconds, 60 seconds, Continuous | 5 seconds, 10 seconds | Customer Protection Scheme (Relay Coordination) |
| Vector Group Options | ZN, ZNyn11, YNd11, ZNd11 | ZN, ZNyn11 | IEC 60076-1 / DIN 42500 |
| Zero-Sequence Impedance ($Z_0$) | Calculated per project (typ. 10 to 150 $\Omega$/phase) | Custom matched to fault clearing limits | Standardized Low-Impedance Testing via DVDF |
| Dielectric Insulating Medium | High-grade inhibited mineral oil or Synthetic Ester (MIDEL 7131) | Vacuum-cast epoxy resin (Class F / Class H) | IEC 60296 / IEC 61099 (Eco-compliance) |
| Auxiliary LV Output Capacity | 50 kVA to 1250 kVA (400V / 230V, 50 Hz) | 50 kVA to 630 kVA | Auxiliary Substation Load (IEC 60076-11) |
| Ambient Operating Range | -35°C to +45°C (Extreme continental Romanian climate) | -25°C to +40°C | SR EN 60076-1 Cl. 4.1 |
Deploying grounding apparatus in Romania requires specialized adaptation to regional soil resistivity, seismic zoning (Vrancea seismic zone), and seasonal temperature fluctuations spanning from -35°C in Transylvanian valleys to +42°C in the Bărăgan plains.
The Black Sea coastal region and Dobrogea host massive onshore wind parks. Medium-voltage collector grids connecting wind turbine generators (WTGs) to main step-up substations operate under extensive underground cable systems. These cables exhibit high capacitive earth fault currents. Our ZN-type grounding transformers, installed alongside Neutral Grounding Resistors (NGR) or arc-suppression coils, eliminate sustained ferroresonance, suppress cable ground overvoltages, and protect converter components from transient switching degradation.
Romania’s renewable energy modernization has driven huge PV investments across Giurgiu, Teleorman, and Dolj. Central inverters feed medium-voltage delta networks. Our compact oil-filled and cast-resin grounding transformers provide precise zero-sequence grounding, allowing selective directional earth fault relays (ANSI 67N) to isolate faulted collector strings without blacking out the entire farm, while concurrently powering tracking actuators and inverter ventilation.
In heavy industrial clusters such as Ploiești refineries, Galați metallurgical complexes, and Craiova automotive manufacturing facilities, process continuity is critical. Our heavy-duty grounding banks prevent ungrounded motor feeders from tripping during first-phase contact, facilitating seamless transitions to controlled alarms and enabling orderly industrial plant shutdown without motor insulation breakdown.
Driven by European Union Green Deal mandates, Romanian energy legislation (ANRE Directives), and major modernization initiatives across Transelectrica’s 400/220/110 kV transmission nodes, purchasing managers and engineering consulting firms (EPCs) are demanding advanced design features:
Due to strict environmental protections near the Danube Delta, Carpathian biosphere reserves, and protected agricultural lands, Romanian utilities increasingly request transformers filled with synthetic ester fluid (e.g., MIDEL 7131). With high fire points (>300°C, K-class) and rapid biodegradability, our transformers eliminate the need for costly concrete deluge fire-retention basins in sensitive installation zones.
Traditional analog gauges are giving way to intelligent electronic devices (IEDs). We provide grounding transformers equipped with fiber-optic temperature monitoring sensors, electronic Buchholz relays, magnetic oil-level transmitters with 4-20mA telemetry, and automated winding temperature indicators (WTI) fully compatible with SCADA architectures across Romanian regional control centers.
Romania exhibits some of Europe's most demanding seismic profiles, governed by intermediate-depth earthquakes originating in the Vrancea tectonic zone. Substation equipment must comply with Romanian Seismic Code P100-1 and IEEE 693 standards. Our mechanical engineering teams utilize dynamic finite-element analysis (FEA) to reinforce tank stiffeners, bushing mounts, and core anchorage structures up to 0.40g peak ground acceleration.
Operating from an expansive, modern 5,500 m² manufacturing plant, our enterprise combines over 34 years of industrial automation and magnetic engineering expertise. Backed by a parent corporate heritage in PC, PLC, and SCADA-based power automation established in 1990, we evaluate transformer performance through the discerning lens of system integrators and panel builders.
Clear, transparent technical and logistics guidance designed to streamline equipment specification, tender evaluation, and import clearance into Romania.
Each export shipment is supplied with a comprehensive documentation dossier required by Romanian customs and grid operators: CE Declaration of Conformity under the Low Voltage Directive (2014/35/EU) and Electromagnetic Compatibility Directive (2014/30/EU), routine factory test certificates (FAT) conducted in accordance with IEC 60076-1 and IEC 60076-6, type test reports from accredited laboratories (including lightning impulse, temperature rise, and short-circuit withstand performance), dimensional drawings, terminal connection diagrams, and dual-language (English/Romanian) installation, operation, and maintenance (O&M) manuals.
Grounding transformers are typically designated by their short-time fault current capability (e.g., 500A or 1000A for 10 seconds or 30 seconds) rather than a continuous kVA rating. We size copper winding cross-sections based on the adiabatic heating calculation: $I_t = A \cdot \sqrt{\frac{\Delta \theta \cdot C}{\rho \cdot t}}$, where current density is restricted to ensure winding temperatures do not exceed the insulation thermal class limits (e.g., 250°C for Class A/mineral oil systems or 350°C for Class F/H dry resin systems) under worst-case fault clearance latencies.
Yes. We provide complete neutral earthing packages comprising the zigzag/grounding transformer, stainless steel or FeCrAl grid Neutral Grounding Resistors (NGR), neutral disconnector switches, current transformers (CTs) for zero-sequence current measurement, and surge arresters mounted in an integrated, outdoor-rated (IP55/NEMA 3R) enclosure. This skid-mounted configuration minimizes on-site cabling and commissioning time across Romanian project sites.
Marine shipments are primarily routed directly to the Port of Constanța via container lines or breakbulk vessels, with typical ocean transit times between 28 and 38 days depending on transshipment hubs. From Constanța, heavy cargo is transported by road or rail directly to substations in Bucharest, Brașov, Timișoara, Cluj-Napoca, or Iași. For urgent project phases, expedited intermodal rail transit via the China-Europe Railway Express reaches European central terminals within 16 to 22 days.
Units engineered for delivery to Vrancea-influenced seismic zones (București, Ploiești, Buzău, Focșani) feature structural reinforcements following Romanian Standard P100-1. High-voltage porcelain or composite bushings are secured with reinforced clamping flanges, interior active assemblies (core and coils) are braced using welded locking structural channels, and heavy-gauge base channels include pre-drilled seismic anchor bolt slots capable of resisting lateral accelerations up to 0.40g.
Partner with an established China manufacturing leader dedicated to serving Romanian utility projects, renewable energy developers, and industrial substations. Connect directly with our electrical engineering team for technical reviews, vector group selections, and tender estimates.
Get a Quote
