Dear All

We are using a 200kw(LO) Sinamics PM240 with CU250S on a hoist application for a 75ton laddle crane. we have removed a 132kw invertek drive. we are using closed loop control with encoder but the encoder got damaged so we now using speed control encoderless.

the joystick is set for 3 upper speeds and 3 lower speeds. with full load we can pick up the load and stop halfway and go up again and there is NO load drop or sag but when we come down on first speed and stop the hoist stops. if we come down on second speed(500rpm) and then move to down on the first speed(88rpm) the hoist continues to move down on the second speed. we get no overvoltage trip only an overvoltage alarm sometimes although we have no braking chopper and no resistor? could this be a problem or should we fix the encoder and go back to speed control with encoder?

Crane is currently standing so any help will be highly appreciated.

Wait....You are screwing around with a ladle crane, the kind that is filled with molten steel that will kill people and burn them horribly (I've been there) if it drops.  And you are wondering if you should replace your encoder.

SLVC does not work at speeds less that 10%.  It is worthless if you need full torque at 0 speed, like a hoist application.

Thanks for the feedback Jeff.

will definitely replace the the encoder and go back to CLVC......

Mr Sietronic you need to check out the Invertec Drive technology, The 3GV technology delivers 100% torque at 0.0Hz, allowing this unique open loop product to be used without any feedback device in traditional closed loop applications. Being able to offer 100% torque from zero without the use of an encoder is most certainly a major benefit for hoisting applications and the has being successfully implemented. And I agree with Jeff, the Molten liquid metal thing can kill people. be safe!

New question published by dhawal is split to a separate thread with the subject Hoisting using CU250S-2DP, Control unit Stopped.

Best regards
Min_Moderator