The "Load Center" Step-Down Strategy

The 630 kVA Dry Type Transformer serves as the industry-standard node for bringing medium voltage power directly onto the factory floor or into the building core. By acting as a localized dry type step down transformer, it converts 11kV or 33kV transmission voltage to 400V immediately adjacent to the consumption point.

This installation strategy is driven by electrical economics. At 630 kVA, the low-voltage output current exceeds 900 Amps. Transmitting this magnitude of current from an outdoor oil substation requires expensive, heavy-gauge parallel cabling or busducts. By placing this dry-type unit indoors-mere meters from the Main Distribution Board (MDB)-engineers effectively eliminate the voltage drop across long LV runs and drastically reduce the capital expenditure on copper conductors.

Dynamic Capacity: AN vs. AF Cooling

A defining feature of this dry type distribution transformer is its thermal expandability. While the nameplate rating is 630 kVA under Natural Air (AN) cooling, the coil geometry is designed to accept cross-flow cooling fans.

AF Mode (Air Forced): By activating the base-mounted fans, the airflow velocity across the coil surface increases, boosting the heat transfer coefficient. This safely raises the continuous output capacity by 40%, effectively pushing the unit to approximately 882 kVA without exceeding insulation temperature limits.
Sizing Efficiency: This allows facility managers to size the transformer based on the average load rather than the absolute peak. The AF system acts as a cost-effective "on-demand" buffer to handle seasonal HVAC spikes or temporary N+1 load shifting in data centers, avoiding the cost of oversizing the base infrastructure.

Cross-flow cooling fans installed on 630 kVA dry transformer

for 40% AF capacity boost.

Structural Integrity & Short Circuit Strength

Products Description

Handling approximately 909 Amps (at 400V) requires a rigid winding structure. We utilize the Cast Resin process where the high-voltage winding is encapsulated in vacuum-poured epoxy reinforced with fiberglass mesh.

Mechanical Rigidity: Unlike VPI or oil units where coils might shift under stress, the cast resin block locks the conductors in place. This grants the transformer exceptional resistance to the radial forces generated during a short circuit, a common risk in heavy industrial grids.

Factory assembly of 630 kVA cast resin transformer showing

rigid steel clamping structure.

Technical Data Sheet

Technical Parameter	Specification Data
Rated Power (AN)	630 kVA (Base Rating)
Rated Power (AF)	Up to 882 kVA (+40% with fans)
Primary Voltage	6kV / 10kV / 11kV / 13.8kV
Secondary Voltage	400V / 415V / 480V
Rated Current (LV)	~909 A (AN Mode)
Impedance Voltage	4.0% or 6.0% (Selectable)
Insulation Class	Class F (155°C) Standard
Enclosure	IP20 (Indoor) or IP23 (Splash-proof)
Standard	IEC 60076-11

Typical Application Context

Automotive Manufacturing: Installing the dry type distribution transformer on mezzanine platforms directly above robotic welding lines to minimize LV cable runs.
Data Centers: Utilizing the AF cooling reserve to handle heat loads during cooling system failures or maintenance windows.
High-Rise Infrastructure: Functioning as the dedicated HVAC transformer on mechanical floors (e.g., Level 30), where hoisting heavy liquid-filled units is structurally impossible.