About 100 people were trapped on a stationary train in Melbourne's west for an hour and a half on Friday afternoon due to an overhead wire fault.

The city-bound train sat idle near Yarraville from about 2pm.

Commuters on the train were unable to disembark until Metro said it was safe to do so about 3.30pm.

The power fault stopped services on sections of the Werribee and Williamstown lines and cancellations extended well into peak hour.