Inquiry Email Whatsapp

SG10 Series Transformer - Overload Solution

National Standard GB6450-1986 Operating Conditions:

Ambient Temperature: Maximum ambient temperature +40°C

Maximum daily average temperature +30°C

Maximum annual average temperature +20°C

Minimum temperature -30°C (outdoor); -5°C (indoor)

Horizontal Axis - Product Load; Vertical Axis - Average Coil Temperature Rise in Kelvin (note, not in degrees Celsius).

Class H insulation products, the long-term withstand temperature of insulating materials is stipulated by the state as 180°C, while the insulating material NOMEX paper used in the SG (B) series transformer products produced by CEEG is Class C (220°C), and the insulating paint is H Class (180°C) or Class C (220°C), which provides a large margin for product overload.


a. When the transformer operates at 70% load, its average coil temperature rise is 57K. If the ambient temperature is 25°C, the coil's average temperature would be T = Coil Temperature Rise + Ambient Temperature = 57 + 25 = 82°C.

b. When the transformer operates at 120% load, and the ambient temperature is 40°C, the coil's average temperature would be T = 133 + 40 = 173°C, which is below 200°C. The localized hot spot temperature within the coil would be 185°C (173 x 1.07).

Note: SG(B) Series transformers achieve a 120% load without the need for fans, and with fan cooling, they can handle short-term overloads exceeding 50%. While we do not recommend prolonged overload operation, this illustrates that SG10 products have the capability to provide additional load in emergency situations, and it also indicates that the products have a sufficiently long lifespan under rated load conditions, reducing long-term investment costs.

Producing H-class (180°C) products using C-class (220°C) insulation materials is far superior to Japanese epoxy products (produced with F-class (155°C) materials with no overload margin).

The ample overload capacity can withstand significant electrical field disturbances, ensuring a stable power supply. This makes SG10 transformers highly reliable equipment for locations with unstable power supply, industries with high overload requirements, and sectors with stringent demands for power stability. Examples include the glass industry, steel industry, automotive manufacturing, commercial buildings, microelectronics industry, cement industry, water treatment and pump stations, petrochemicals, hospitals, data centers, and more.

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site, we assume that you accept such use.