This on-load tap changer is suitable for power or industrial transformers with a rated voltage of 35 to 110 kV, a maximum rated through-current of 500 A or less, a frequency of 50 Hz to 60 Hz, a three-phase, Δ(D) or Y-connected neutral regulating connection to change the transformer connectors to change the transformer's output voltage to achieve a stable voltage at the output end within a specified range under load conditions; or to increase or decrease the output voltage according to the requirements of the load to achieve the purpose of adjusting the voltage on the line.

Designation | FVI(III)200 | FVI(III)350 | FVI(III)500 | ||||||
Max. rated through-current Ir (A) | 200 | 350 | 500 | ||||||
Phase | 1 | 3 | 3 | 1 | 3 | 3 | 3 | 3 | |
Connection Methods | - | Y | Δ | - | Y | Δ | Y | Δ | |
Withstand short-circuit capacity (kA) | Thermal stabilization (3s) | 4 | 5 | 7 | |||||
Dynamic stabilization (peak) | 10 | 12.5 | 17.5 | ||||||
Max. rated step voltage | 10 contact | 1500 | 1500 | 1500 | |||||
12 contact | 1400 | 1400 | 1400 | ||||||
14 contact | 1000 | 1000 | - | ||||||
Rated step capacity (kVA) | 10 contact | 300 | 525 | 400~525* | |||||
12 contact | 280 | 420 | 325~420* | ||||||
14 contact | 200 | 350 | - | ||||||
Number of tap positions (max.) | Linear modulation:14 Forward and reverse (thickness) modulation:27 | Linear modulation:12 Forward and reverse (thickness) modulation:23 | |||||||
Ground isolation(kV) | Insulation grade | 35 | 60 | ||||||
Highest voltage for equipment | 40.5 | 72.5 | |||||||
Power frequency test voltage | 85 | 140 | |||||||
Impulse test voltage | 200 | 350 | |||||||
Seal test | Working pressure | 3×104Pa | |||||||
Test pressure | 6×104Pa, No leakage for 24 hours | ||||||||
On-load tap changer weight (without oil) | 100~140 | 120~150 | 190~200 | ||||||
With motorized mechanism | CDF2 | ||||||||
Protecting relay | QJ4-25 Neutralized impact oil speed 1.0m/s±10% |






1. Q: What are your main products?
A: For over four decades, our company has specialized in developing and producing on-load tap changers. Our extensive product range caters to power transformers, furnace transformers, specialized transformers, and various other industries.
2. Q: Are you a manufacturer?
A: Yes. Wukai Electric (Jiangsu) Co., Ltd. proudly is a leading on-load tap changer manufacturer. With a state-of-the-art factory spanning 20,000 square meters and a dedicated workforce of over 100 employees, our production line has delivered nearly 100,000 units currently operational in networks worldwide. Additionally, we offer comprehensive OEM and ODM services to meet diverse customer needs.
3. Q: How do you control the quality of your products?
A: We implement a stringent quality control system throughout every stage of the production process. Upon completion, each product undergoes thorough testing by relevant standards. A detailed factory inspection report accompanies all shipping documents, ensuring transparency and reliability.
4. Q: What's your payment terms?
A: We are flexible and accept various payment terms such as T/T, L/C, and more.
5. Q: What are your products packaged for transportation?
A: Our products are securely packaged in robust composite wood crates to ensure safe transportation.
6. Q: What kind of credentials do you have?
A: We hold several prestigious credentials including a Quality Management System Certificate and a High-tech Enterprise Certificate, among others.
7. Q: Can I come to visit your factory?
A: Absolutely! We warmly welcome you to visit our factory and witness our operations firsthand.