To switch the motor from star to delta connection, our Tesys star-delta starters must actuate their delta contactor with a slight delay after opening the star contactor to ensure adequate breaking time for the star contactor. Generally speaking, the larger the contactor the longer it takes to open the power circuit.
For contactors rated LC1D80* (80A AC-3) and below, the switching time of 40 ms +/- 15 ms between opening of the NC contact and closing of the NO contact on the LADS2 time delay module is sufficient to ensure this breaking time.
This is not the case for LC1D115**, LC1D150** and larger contactors. The changeover time provided by the LADS2 module is no longer sufficient and there will be a risk of short-circuiting.
The LADT2 auxiliary contact block combined with a CAD32** (replace ** with coil voltage code) contactor relay inserted in the control section will ensure that the star contactor opens before the delta contactor closes.
For contactors rated LC1D80* (80A AC-3) and below, the switching time of 40 ms +/- 15 ms between opening of the NC contact and closing of the NO contact on the LADS2 time delay module is sufficient to ensure this breaking time.
This is not the case for LC1D115**, LC1D150** and larger contactors. The changeover time provided by the LADS2 module is no longer sufficient and there will be a risk of short-circuiting.
The LADT2 auxiliary contact block combined with a CAD32** (replace ** with coil voltage code) contactor relay inserted in the control section will ensure that the star contactor opens before the delta contactor closes.
Released for:Schneider Electric Ireland
