Using a temperature measurement, the field induced dissipation in polycrystalline YBa2Cu30 x at T,~ T c has been measured for magnetic fields up to 2970 Oe applied at constant ramp rates, in the absence of a transport current. At 4.85 K results show that for H > 500 Oe the dissipated energy was rate independent in the magnetization run, rate dependent in the hysteretic run, and proportional to the cube of the applied field for both the magnetization and hysteretic runs. A more complex rate and field dependence was observed at lower fields. We also find the surprising result that the dissipation is equal for both increasing (HI) and decreasing (HI) H in magnetization runs for all applied fields, but in hysteretic runs the dissipation is less for HI than HI, but only at low fields. B has been simultaneously measured and found to be rate dependent up to 100 Oe and then to increase nearly linearly with H, independent of the rate, up to 2000 Oe for both magnetization and hysteretic runs. The dissipation and magnetization results have been modelled using a classical eddy current meehanism and a Rayleigh-Bean model. Although the Rayleigh -Bean model was inconsistent with the experimental data at lower fields, the classical model was roughly consistent with the experimental observations for ramp rates _> 2880 Oe s-1 in hysteretic runs below 500 Oe. The dissipation was found to be an appreciable fraction of the magnetization energy at 3000 Oe and typically three to four orders of magnitude larger than that expected from eddy current loss in the normal state.