buffer transformer

Perhaps you mean an isolation transformer. Transient voltages or spikes contain high frequency components which are absorbed in the iron core and converted to heat. Consequently an isolation transformer will reduce the amount of transient or disturbance on the power line and thereby provide a buffer.

If you decide to use one, be sure that it has more capacity than you need. This is called "de-rating" which means that you are leaving extra capacity unused so that the magnetic core is not saturated.