MOTORDREV

The invention relates to a motor drive (10) comprising a rectifier bridge (12) for connection with mains, a converter bridge (26) configured to be connected with an elevator motor and an intermediate DC circuit (28) in-between, whereby between a positive and a negative branch (30, 32) of the intermediate DC circuit (28) at least one capacitor (34) and/or battery is connected, whereby at the mains side of the rectifier bridge (12) a controlled main relay (14) with contacts (16a, 16b, 16c) is arranged, which are configured to connect or disconnect the rectifier bridge (12) with the corresponding mains phase (L1, L2, L3), characterized in that the motor drive (10) comprises a charging circuit (24) being connected between the mains and the rectifier bridge (12) and/or intermediate DC circuit (28), which charging circuit comprises at least one charging switch (20) connected in series with at least one current limiting component (22, 42), and which motor drive (10) comprises a voltage sensor (38) connected between the positive and the negative branch of the intermediate DC circuit (28), which voltage sensor (38) is connected to a fault evaluation circuit (40) comprising at least one reference value and a comparator, which evaluation circuit (40) is configured compare the actual sensor (38) signal of the voltage sensor (38) to the reference value and to operate the main relay (14) dependent on the comparison result.