We have implemented ATV 630 with by pass contactor scheme for starting 03 numbers Multistage Plunger pump system. ATC 630 donot have line synchronization provisions, so we have opted for open transition.
Motor is 400 V 50Hz 200 KW 1480 rpm and pump is 208 rpm with gear system in between. Pump starts smoothly on VFD but trips on high current once transfer to line. From our earlier experience of similar scheme in grinding mill we have included a delay of 200 milisec in PLC controlling all contactors transfer to minimize motor magnetizing current effect. Just want to clarify my doubt of over speeding limit of the motor before the transfer. What will happen if we increase motor speed to 60-65 Hz before transfer and at time of re-engaging it is more than 1480rpm as it will give us optimum time to complete transfer or it strictly has to be below 1480 rpm . I think due to 208 rpm pump speed , motor speed is decreasing very rapidly during power shifting.
Any suggestion will be highly appreciated. Understand that vfds will synchronization will be useful but they are too expensive, and most of their other high end functions are not utilized in this scenario. Reduced voltage Soft starters usually donot assist with such PD loads as we already had to replace one for our earlier grinding case due to available genset size.
Motor is 400 V 50Hz 200 KW 1480 rpm and pump is 208 rpm with gear system in between. Pump starts smoothly on VFD but trips on high current once transfer to line. From our earlier experience of similar scheme in grinding mill we have included a delay of 200 milisec in PLC controlling all contactors transfer to minimize motor magnetizing current effect. Just want to clarify my doubt of over speeding limit of the motor before the transfer. What will happen if we increase motor speed to 60-65 Hz before transfer and at time of re-engaging it is more than 1480rpm as it will give us optimum time to complete transfer or it strictly has to be below 1480 rpm . I think due to 208 rpm pump speed , motor speed is decreasing very rapidly during power shifting.
Any suggestion will be highly appreciated. Understand that vfds will synchronization will be useful but they are too expensive, and most of their other high end functions are not utilized in this scenario. Reduced voltage Soft starters usually donot assist with such PD loads as we already had to replace one for our earlier grinding case due to available genset size.