Services have since resumed however on both circles after being down for around an hour.
A shuttle service that had been set up in response to the power failure had been set up between Shields Road and St Enoch, but was also stopped as the transport firm was forced to "shut down and restart the system".
Normal services have resumed on the Subway however with an update confirming: “Subway is now running. All stations are open and services are running as normal on both circles. Apologies for the inconvenience and thank you for your patience.”