For improving rated current flow capacity of 126 kV single-break vacuum circuit breaker（VCBs）further

the temperature rise feature of 126 kV vacuum circuit breaker adopting 4 kinds of different AMF contact structures is compared and studied in this paper.The 4 kinds of AMF contacts are 2/3 turn coil-type AMF contact

3/4 turn coiltype AMF contact

horseshoe-type AMF contact and slotted horseshoe-type AMF contact

respectively.The finite element simulation result shows that

in case of flowing current at 3 150 A

the hot state AC resistances for the 4 kinds of AMF contacts are 30.2

36.9

24.0 and 16.3μΩ

respectively.Temperature distribution of the 4 kinds of VCBs is obtained by employing finite volume method.Temperature-rise simulation models are verified by experimental results at flowing current at 2 500 A.It is shown by the result that the calculation errors of the simulation model within5 temperature measurement points around interrupter is less than 10%

the maximum calculation error of 36%is on the terminal of circuit breaker since the influence of external wiring is not considered.It is found through simulation of temperature rise feature of 4 kinds of AMF contacts at 3 150 A that the slotted horseshoe-type AMF contact has the best temperature-rise performance among above 4 kinds of contact structures and its temperature rise performance at nominal rated current of 3 150 A complies with China National Standard（GB）requirement

in which the temperature rise at the highest temperature measurement point is 66 K.