Logic induction hob

[bob s]

hi yes its me again. we have just moved in to a house which has a logic schott ceran induction hob, i have bought a new set of pans, given it a good clean and always switch the fan above on before i use it. but when i switch any of the 4 rings on they will glow red for a while then i will hear a quiet switch noise the red glow will go out but come back on a minute or 2 later is this normal or do i have a fault ? many thanks for any help or suggestions thanks again bob,