Festo Контроллер двигателя SEC-ST - Manual (Page 15)

Contents and general instructions
XIII
Festo SEC−ST−48−6−P01−EN en 0606c
Phase current
Phase current is the current that flows through strand of a
winding. At the maximum phase current, the stepping motor
has its maximum holding torque. The phase current should
be adjusted to the load. That is, it does not always make
sense to set the motor’s maximum phase current. If the motor
is run without load or with a torque lower than its nominal
torque, it can also carry out steps too far or begin to resonate
(see above), which is equivalent to a loss of step.
The set phase current flows at all times through the active
coils of the motor, even when the motor is standing still. An
advantage of this is that the motor has a certain resting torĆ
que and can be loaded with its holding torque during standĆ
still. Also, the motor is warmed even at standstill. If this holĆ
ding torque is not needed in standstill, it makes sense to
reduce the phase current when the motor is at standstill. The
Festo stepping motor controller SEC−ST−48−6−P01 offers this
option.
With these attributes of the stepping motor considered, it
provides an economical positioning variant with adequate
precision.