Abstract: The voltage instability is a growing problem in the modern power systems and is associated with rapid voltage drop due to heavy load demand. Fast computing techniques have been tried to properly analyze the voltage stability for predicting the onset of voltage collapse so as to avoid any unwanted events of the system. Several approaches are available in the open literature for assessing the voltage stability of a power system. A fast and easier way to assess the voltage stability of power system is through its equivalent network and widely explored in current literature. This study presents a review on the voltage stability assessment methodologies particularly based on the network equivalent techniques.