Voltage Detector Unit, DY1811 certified for MV cabinets The Voltage Indicator Unit SMTE is a safety device, which detects the presence or absence of Medium Voltage inside distribution cabinets. SMTE should be used in combination with appropriate MV-isolator in the range 8kV-24kV. Each system is made up of one base (SMTE/F) installed on the panel of the cabinet and three plug-in led indicators (SMTE/M), one for each phase. Different models are available to match different MV-isolators models. SMTE is specifically certified for ENEL distribution MV cabinets.