A simple plane change puts a satellite in one orbital plane into another, meaning there is a change in its inclination. For a change in inclination between two circular orbits a burn can be performed at the ascending or descending node of the orbital plane.
The equation for Δv for the plane change is given by:
Δv = 2 v sin(Δi/2)
This implies two important findings:
1) A large inclination change, over 60ᵒ causes
Δv > v
2) Inclination changes at slower v, requires less Δv. Therefore, inclination maneuvers at apoapsis require less Δv.