Magnetic saturation
The limit beyond which the core can no longer channel the flux.
Definition
Magnetic saturation is the state in which a magnetic material can no longer increase its flux density, even as the magnetising current is raised. All the magnetic domains of the material are then aligned: the core has reached its maximum, around 1.5 to 1.8 tesla for silicon sheets.
When a core saturates, its permeability collapses and it barely opposes the current: the unit draws a very high current, heats up and hums. Saturation can be caused by an overvoltage, too low a frequency, a stray DC component, or the switch-on transient (inrush current).
A transformer is always sized to work well below the saturation threshold, with a safety margin.
The ABL tip
A DC component, even a small one, on your network (electronic loads, rectifiers) can saturate a standard transformer. Flag this risk to us: we adapt the working flux density or add an air gap to avoid it.
