Iwould say you have to install a 3 phase protector at the service entrance to avoid this problem.
I would like to ask if someone have made measurements of the shape of the wave at the service entrance in any distribution system of any electrical utility co.in any city or country.
I´m curious to learn if a SPD should include EMI/RFI noise filtering or if a SINE WAVE TRACKING WILL BE ENOUGH in order to supply a clean signal to the utility customers.
thanks for your help,
GERARDO TAMA