Question:
The rated motor current (0x6075) cannot be increased further although the maximum output current specified on the device has not yet been reached. What can be the reason if e. g. for an i700 5 A-axis module the rated motor current can only be increased up to 3.3 A?
Answer:
As specified in the CiA402 device profile, for the i700, the maximum current (0x6073) is indicated in percent related to the rated motor current (0x6075).
The maximum current in percent (0x6073) is default set to 150 %. The maximum current can, of course, only be set up to the device limit (in the above example 5 A). With an Imax = 150 % setting, the limit value for the rated motor current, which acts as a 100 % reference value, can be calculated using a rule of three: 150 % = 5 A --> 100 % = 3.3 A.
I. e. you can only select a higher rated motor current if the maximum current has been reduced accordingly before.
For other Lenze drive controller series, the rated motor current and the maximum current are directly set in Amps and thus independently of each other. It is true that the percentage settings in the i700 lead to an 'unusual' interdependency between the two parameters. But, on the other hand, this dependency reduces the risk of a motor overload due to faulty parameter setting. The motor current is always automatically limited to 150 % corresponding to the selected motor unless the user deliberately increases the maximum current.
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