UNE 21825:1983
APARAMENTA INDUSTRIAL DE BAJA TENSION. DETECTORES DE PROXIMIDAD INDUCTIVOS. FORMA C, PARA CORRIENTE CONTINUA, 3 O 4 BORNES
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR FOR INDUSTRIAL USE. INDUCTIVE PROXIMITY SWITCHES. FORM C, FOR DIRECT CURRENT, 3 OR 4 TERMINALS.