Depending on the setting, the P632 monitors the frequency to determine whether it exceeds or falls below set thresholds. If an operate threshold in excess of the set nominal frequency is set, the P632 checks to determine whether the frequency exceeds the operate threshold. If an operate threshold below the set nominal frequency is set, the P632 checks to determine whether the frequency falls below the operate threshold. If it exceeds or falls below the set threshold, a set timer stage is started. The timer stage can be blocked by way of an appropriately configured binary signal input.