steve708
Member
I have several long conveyor systems (6" chain) powered by multiple 7.5 HP DC motors. DC drives are AB 1370 Series B and are very old and no longer supported. Each motor armature is wired in parallel to the armature circuit of the drive, and each motor has a resistor in series to balance the effects of different wire lengths. Each motor field is wired in parallel to a fixed 150VDC field supply and each motor has a variable resistor in the field circuit to allow for tweaking the speed of individual motors to pull slack chain out between motors. There is an external feedback loop based on chain movement that creates a trim signal to combine with the main speed control pot, and armature feedback in the DC drive is sufficient.
It is time to upgrade these DC drives to something that is supported, and PowerFlex DC is the preferred option. It seems though that a fixed field supply is no longer available and the drive wants to precisely control field current which takes away the ability to individually adjust motor speeds. I am also being told that the way to do things now is to put in a DC drive for each motor individually and network them together to accomplish the load sharing.
It is cost prohibitive to change to AC motors, and also to install multiple DC drives in existing control panels while absolutely not causing one second of downtime due to the upgrade. Also, the conveyors cannot be run during non-production time for testing.
What I really need is a new up to date DC drive which can directly replace my old system with no hassles - any suggestions?
It is time to upgrade these DC drives to something that is supported, and PowerFlex DC is the preferred option. It seems though that a fixed field supply is no longer available and the drive wants to precisely control field current which takes away the ability to individually adjust motor speeds. I am also being told that the way to do things now is to put in a DC drive for each motor individually and network them together to accomplish the load sharing.
It is cost prohibitive to change to AC motors, and also to install multiple DC drives in existing control panels while absolutely not causing one second of downtime due to the upgrade. Also, the conveyors cannot be run during non-production time for testing.
What I really need is a new up to date DC drive which can directly replace my old system with no hassles - any suggestions?