Star-delta electric switch MN series

camrotaryIP65

The MN series motor protection switches are cam switches with thermal over-current trip devices integrated within the switch. The base unit forms the contact chamber with the cam wheel for function control. In the event of excess current, the bi-metals cause the switching latch to be operated via a trip shaft. This interaction enables a multitude of switching programmes with integrated motor protection to be produced. Due to the switching of the bi-metals within the current circuit there are 2 different series in terms of the setting ranges: for On/Off switches, reversing switches, pole-changing switches (1 rotary speed protected) and single-phase starter switches 12 setting ranges of 0.3 to 21.5 amps have been defined. The star-delta switches are sub-divided into 7 setting ranges of 2.85 to 37 amps, with the bi-metals wired up in such a way that they are in the motor's phase current circuit. The motor coil is thus protected both in the star and the delta positions. The current to be set on the setting scale is the motor's rated current. No conversion is required. Special cases Star-delta switches for extremely difficult MN2Y start-ups are used where - due to the drive system – a long start-up period in the star position is required. So that the motor protection is not triggered during the start-up phase, the bi-metals are placed such that only in the delta position are they connected up in the current circuit. With this form of switching the motor is thus protected only in the delta position. Pole-changing switches – both rotary speed protected – MNDP.