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Phase Current

An important parameter in the selection or design of the driver is the current it sends through the coils of the motor. The current specified for the motor is the maximum current that is allowable per phase. To avoid damage to the motor it is decisive to ensure that this current is not exceeded. This implies that the current of the drive must be restricted to this or any lower value. Many drives allow limiting the current either by potentiometer, DIP switches or by soft setting for example through the indexer. As step motors tend to run hot it is advisable to use a current that is as low as possible while still maintaining reliable operation of the application. This means that in many applications the actual maximum phase current used will be lower than that allowed by the motor manufacturer. This will help to maximize the lifetime of motor and driver hardware.

In case of a bifilar motor, the wiring configuration needs to be taken into account. The allowable current in a series configuration is half that of the parallel connection.