In recent years, automatic audio anomaly detection has gained considerable attention. However, most existing methods and benchmarks assume stationary or periodic signals, limiting their applicability to industrial environments characterized by non-stationary operating regimes such as speed ramps and transient load variations. We introduce the ALERT Dataset, a large-scale collection of non-stationary vibration recordings from electric powertrains acquired on an industrial end-of-line test bench. Each recording captures ramp-up and ramp-down phases with continuously varying rotational speed and includes synchronized speed measurements to enable explicit conditioning on operational dynamics. The dataset comprises 224 healthy training recordings and 80 healthy test recordings, along with an additional 80-sample hold-out set reserved for anomaly generation. From this hold-out set, multiple anomalous test suites (80 samples each) are constructed via expert-designed amplitude-based degradations and structured noise perturbations at varying signal-to-noise ratios, simulating realistic fault scenarios. Models are evaluated by discriminating these anomalies from the 80 healthy test recordings under a one-class learning paradigm. The benchmark further supports diverse protocols, including zero-shot cross-phase testing. To our knowledge, the ALERT Dataset is the first large-scale collection of non-stationary industrial vibration signals with synchronized speed references, addressing a critical gap in existing benchmarks. The dataset is publicly available on Zenodo.