the product can apply to automatic liquid level control and protection of single phase stainless steel/cast iron submersible pump for deep well,centrifugal pump, pipeline pump with 0.37-4KW (0.5HP-5.5HP)direct startup type. Its special layout makes it possible to realize the sensitive and reliable function of stopping protection against pump dry-running without installing lower water tank (well) probe, which makes it more convenient and economical to install deep-well submersible pump and pipeline pump. Input voltage: AC220V Single phase; Output power: 0.37-2.2KW/3-4KW Application: specially designed for water supply, supporting duplex pump running same time