Belt conveyors play an important role in continuous dry bulk material transport. Large scale belt conveyor systems consume a considerable amount of electricity. The approach of controlling the belt speed in such a way that the belt's volumetric capacity is fully utilized under all operational conditions has been proven to significantly reduce the energy consumption of a belt conveyor. Current research on speed control for belt conveyors mainly focuses on the calculation and the prediction of possible energy savings. Few studies focus on the dynamics of belt conveyors in transient operation. There are however no studies that describe the operation of speed controlled belt conveyors during transient operation. This paper presents a three-step method that can be used to determine a proper way to accelerate a speed controlled belt conveyor during transient operation. This method takes the potential risks in transient operation and the conveyor dynamic performance into account. A case of horizontal conveyor system is studied and the three-step method is applied. In the case study, a predictor of the permitted maximum acceleration is calculated. Simulations with the predicted acceleration time are carried out to determine the acceleration operation and to analyse the conveyor dynamics. The simulations are based on an existing finite element model of a belt conveyor.