GCP - Group Control Panel
The GCP provides power to the master control card units (MCC) when the fire alarm status is normal (closed). If the fire alarm is activated the MCC units are powered down allowing the curtains to deploy to their fire operational position under gravity. When the alarm is reinstated the MCC's are powered up, thus retracting the curtains. If there is a mains failure, the back-up batteries provide power to the MCC's for up to 3 hours, (subject to load), and prevent deployment until discharged unless overridden by an alarm signal to activate.