An electrosurgical system comprising: an electrosurgical instrument comprising: a first jaw including a plurality of electrodes (103a, 103b, 105a, 105b) including two coagulation electrodes separated by a first, close spacing or a second, large spacing; and a second jaw including an electrode and opposing the first jaw, the second jaw coupled to the first jaw to capture tissue between the first and second jaws (102, 104); and a radio frequency amplifier configured to supply RF energy to coagulate and cut tissue, wherein the RF amplifier is arranged to supply RF energy between the plurality of electrodes (103a, 103b, 105a, 105b) at a first rate for pre-cutting tissue disposed at the jaws and to monitor a phase defined as the phase difference between voltage and current supplied until the phase value equals or exceeds a first predetermined phase value and subsequently supplying RF energy at a second rate sufficient to cut tissue; characterized in that the first predetermined phase value is smaller than a second predetermined phase value at which coagulation of tissue is expected to occur and in that the RF amplifier is configured to select the first predetermined phase value based on the spacing between the plurality of electrodes (103a, 103b, 105a, 105b) of the first jaw is configured to select the first rate at which the RF amplifier is to supply RF energy based on the first predetermined phase value, the first predetermined phase value for closely spaced electrodes being lower than the first predetermined phase value for electrodes spaced larger than the closely spaced electrodes and the first rate for the closely spaced electrodes being greater than the first rate for electrodes spaced larger than the closely spaced electrodes. an electrosurgical instrument comprising: a first jaw including a plurality of electrodes (103a, 103b, 105a, 105b) including two coagulation electrodes separated by a first, close spacing or a second, large spacing; and a second jaw including an electrode and opposing the first jaw, the second jaw coupled to the first jaw to capture tissue between the first and second jaws (102, 104); and a radio frequency amplifier configured to supply RF energy to coagulate and cut tissue, wherein the RF amplifier is arranged to supply RF energy between the plurality of electrodes (103a, 103b, 105a, 105b) at a first rate for pre-cutting tissue disposed at the jaws and to monitor a phase defined as the phase difference between voltage and current supplied until the phase value equals or exceeds a first predetermined phase value and subsequently supplying RF energy at a second rate sufficient to cut tissue; a first jaw including a plurality of electrodes (103a, 103b, 105a, 105b) including two coagulation electrodes separated by a first, close spacing or a second, large spacing; and a second jaw including an electrode and opposing the first jaw, the second jaw coupled to the first jaw to capture tissue between the first and second jaws (102, 104); and a radio frequency amplifier configured to supply RF energy to coagulate and cut tissue, wherein the RF amplifier is arranged to supply RF energy between the plurality of electrodes (103a, 103b, 105a, 105b) at a first rate for pre-cutting tissue disposed at the jaws and to monitor a phase defined as the phase difference between voltage and current supplied until the phase value equals or exceeds a first predetermined phase value and subsequently supplying RF energy at a second rate sufficient to cut tissue; characterized in that the first predetermined phase value is smaller than a second predetermined phase value at which coagulation of tissue is expected to occur and in that the RF amplifier is configured to select the first predetermined phase value based on the spacing between the plurality of electrodes (103a, 103b, 105a, 105b) of the first jaw is configured to select the first rate at which the RF amplifier is to supply RF energy based on the first predetermined phase value, the first predetermined phase value for closely spaced electrodes being lower than the first predetermined phase value for electrodes spaced larger than the closely spaced electrodes and the first rate for the closely spaced electrodes being greater than the first rate for electrodes spaced larger than the closely spaced electrodes.