Electric field

accompanying with the magnetic field produced by high current

can generate eletro-magnetic force in power system

which enormously affects the electrical treeing process. Understanding electrical tree characteristics of room temperature vulcanized（RTV） silicone rubber under magnetic field is of great importance for wide application of high power DC cable. Therefore

with specimens made of RTV silicone rubber

repetitive pulse voltage and AC voltage supply

the effect of magnetic field on electrical tree characteristics with different voltage was investigated. Results show that

with the increase of the magnetic flux density

the electrical tree initiation voltage decreases under the pulse power supply and AC voltage supply. The length of electrical tree obviously increases due to the high magnetic field. Typical profiles of electrical tree change with the increase of magnetic flux density under AC voltage. When the magnetic flux reaches 400 m T

all electrical trees are bush tree

and the electrical tree growth rate obviously decreases

but the fractal dimension of the electrical tree at 400 m T is significantly higher than that at 0 m T. This indicates that magnetic field improves the initial probability of electrical tree under both repetitive pulse voltage and AC high voltage supply. The growth of electrical trees becomes more dense with the increase of magnetic flux density. When the electrical tree grows to a certain degree

the promotion of magnetic field on the growth of electrical tree becomes weaken under AC voltage supply

while it is still strong under repetitive pulse voltage supply. The results provide a reference for further study on the growth mechanism of electric tree in silicone rubber under magnetic field.