Abstract - The use of parallel fuses has become a critical solution for protecting large Padmount-type transformers (4 to 8MVA) in renewable energy applications due to the scarcity of high-current fuses. Adhering to IEEE Std. C37.48-2020, which specifies a maximum resistance variation of 2-3% for parallel fuse configurations, ensures optimal performance.
Keywords— Parallel fuses, Transformer protection, Fuses
I. GENERAL
According to IEEE Std. C37.48-2020 “IEEE Guide and Tutorial for the Application of High-Voltage (>1000 V) Fuses and Accessories” clause 5.1.5 “Current rating and interrupting capacity considerations for fuses in parallel,” this standard refers either to expulsion or current limiting fuses.
“Configurations of two or more fuses have been successfully used in parallel for many years. This has been accomplished by installing two or more fuses and/or their fuse supports connected in parallel. This can be done by a user, a third-party assembler, or by a manufacturer supplying a device that holds two or more fuses in a single fuse support. This provides for increased current ratings.”
II. APPLICATION OF FUSES IN PARALLEL
In recent years, there has been significant growth in the application of fuses in large Padmount-type transformers used in renewable energy generation (4 to 8MVA). Due to the limited availability of fuses with high current ratings, most coordinated protective fuses are connected in parallel.
Our website's coordination tool advises maintaining a balanced resistance among current paths, with a maximum allowable variation of 2-3% as specified in clause 5.1.5 of IEEE Std. C37.48-2020 for paralleling applications.
Additionally, our tool recommends the following maximum fuse paralleling configurations: up to 2 fuses for 25kV class and higher, up to 3 fuses for up to 15.5kV class, and up to 4 fuses for 8.3kV class and below. These recommendations are based on our extensive experience and are widely adopted by our customers.
Based on the recommendations of the IEEE Std. C37.48-2020, The H-J Family of Companies has been recommending parallel fuses for more than 20 years with excellent results after thousands of applications. We provide around 10,000 fuses per year for parallel application.
For more information please refer to test report 38kV OSP 200A Design Test Report Rev 0 8-4-2016. The test was approved per IEEE Std. C37.41-2016 showing the reliable operation of this parallel fuse.
III. REFERENCES
Guide and Tutorial for the Application of High-Voltage (1000 V) Fuses and Accessories, IEEE Std. C37.48-2020, 2024
IEEE Standard Design Tests for High-Voltage (>1000 V) Fuses and Accessories," in IEEE Std C37.41-2016 (Revision of IEEE Std C37.41-2008) , vol., no., pp.1-141, 9 Dec. 2016, doi: 10.1109/IEEESTD.2016.7781575.
Disclaimer: The information provided in this FAQ (Frequently Asked Questions) is for informational purposes only and is not intended as a substitute for
professional engineering advice. While H-J has made every effort to ensure the accuracy and reliability of the content, we do not guarantee its completeness
or applicability to all situations. Use of this information is at your own risk.
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