A measurement system has a transmitter for determining the position of a movable element, and a first energy store which, in the event of failure of an external electrical supply unit of the transmitter, supplies at least a part of the transmitter with electrical power such that a stored count of the transmitter is maintained in the event of failure of the external electrical supply voltage. The first energy store produces a first auxiliary supply voltage, wherein a first data item is stored in the transmitter when a reference mark of the transmitter is detected for the first time. The first data item is deleted in the event of failure of the external electrical supply voltage for the transmitter and failure of the first auxiliary supply voltage for the transmitter. As a result, an incorrectly determined position resulting from a failure of the electrical power supply for the transmitter can be identified.