Hi All,
I have a lifting/hoist application that I am using a powerflex 755 1hp drive. I am using a 1/3hp SEW gear motor that is rated at 0.57A 480V delta.
I was unable to complete a static autotune with the powerflex 755 drive (the drive faults with code 77 IR Volts Range). But i am still able to control the hoist. Although the problem is that i don't have a great amount of lifting power. I contacted rockwell and they basically said that the drive doesnt like something from the nameplate when doing the autotune. I contacted SEW and confirmed all values were correct. Now aside from not having the best control over the motor which i was expecting to be improved with at least a static tune I have started thinking about other things that seem odd to me.
First of all, I have 2 of these same applications on the same machine, both behaving in the same manner (failed autotune, limited lifting power).
What i find very difficult to understand is that during the cycle of the equipment the hoist is commanded to lift until it hits a cylinder at which point it will lift the cylinder which in turn changes the state of a prox that is barrel mounted, at which time the hoist is directed to lower.
I have seen multiple times that when there is a heavy load (which is should lift under normal circumstances) it will come in contact with the cylinder and not have enough power to oppose the compressed air, effectively stalling the motor. What i would expect to happen would be the drive would trip with a motor OL. However this is not the case. I simply see the drive sitting there putting out no more than the rated nameplate current. I have the overload factor set at 1.0 so i would expect to see it trip quite quickly.
Can anyone think of a reason as to why this is? the duty cycle is very low on this equipment and could probably be run at 150% rated current for it's lifting time (approx. 3-5 seconds every 60 seconds).
I have checked the drive parameters to ensure that the maximum current parameter is set above the nameplate value (it is set to the default 3.78A that the drive is rated to output).
I'm at a loss here because I have definetly seen applications where i am running over current for a period of time on conveyors due to jams which inherently clear themselves (in which case i typically set the overload factor to around 1.15)
Any help would be appreciated.
I have a lifting/hoist application that I am using a powerflex 755 1hp drive. I am using a 1/3hp SEW gear motor that is rated at 0.57A 480V delta.
I was unable to complete a static autotune with the powerflex 755 drive (the drive faults with code 77 IR Volts Range). But i am still able to control the hoist. Although the problem is that i don't have a great amount of lifting power. I contacted rockwell and they basically said that the drive doesnt like something from the nameplate when doing the autotune. I contacted SEW and confirmed all values were correct. Now aside from not having the best control over the motor which i was expecting to be improved with at least a static tune I have started thinking about other things that seem odd to me.
First of all, I have 2 of these same applications on the same machine, both behaving in the same manner (failed autotune, limited lifting power).
What i find very difficult to understand is that during the cycle of the equipment the hoist is commanded to lift until it hits a cylinder at which point it will lift the cylinder which in turn changes the state of a prox that is barrel mounted, at which time the hoist is directed to lower.
I have seen multiple times that when there is a heavy load (which is should lift under normal circumstances) it will come in contact with the cylinder and not have enough power to oppose the compressed air, effectively stalling the motor. What i would expect to happen would be the drive would trip with a motor OL. However this is not the case. I simply see the drive sitting there putting out no more than the rated nameplate current. I have the overload factor set at 1.0 so i would expect to see it trip quite quickly.
Can anyone think of a reason as to why this is? the duty cycle is very low on this equipment and could probably be run at 150% rated current for it's lifting time (approx. 3-5 seconds every 60 seconds).
I have checked the drive parameters to ensure that the maximum current parameter is set above the nameplate value (it is set to the default 3.78A that the drive is rated to output).
I'm at a loss here because I have definetly seen applications where i am running over current for a period of time on conveyors due to jams which inherently clear themselves (in which case i typically set the overload factor to around 1.15)
Any help would be appreciated.