Status of the commissioning of the CMS GE1/1 station.

In December 2018 the Large Hadron Collider entered the Long Shutdown 2 phase, dedicated to the upgrade and maintenance of the infrastructures. In order to maximize the collision data statistics collected by the experiments, the High-Luminosity LHC will increase the instantaneous luminosity up to a factor 5--7 with respect to the original LHC design. To cope with this, the LHC experiments must be upgraded, and in particular, the CMS experiment has begun the installation of detectors based on triple-GEM technology, which aims at keeping under control the trigger rate in the high-pseudorapidity region, sustaining a high level of radiation while maintaining their design performance and increasing the redundancy for muon track reconstruction. In this contribution the status of commissioning of GEM detectors in CMS will be illustrated, focusing in particular on the role played by HV trips in the chamber operation and on the strategies adopted to minimize their occurrence to grant smooth operation. In addition, the operation of these detectors in the presence of magnetic field ramps will be presented, illustrating phenomena observed in CMS and in a dedicated test set up in the CERN North Area.