Specifications

20 Gear Drive, Plymouth Ind. Park, Terryville, CT 06786
Tel: [phone] Fax: [phone] http://www.amci.com
CHOOSING YOUR SETTINGS
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DIP Switch Settings (continued)
Current Loop Gain (SB1-4 & SB1-5)
Current loop gain refers to the gain of the closed loop amplifier that controls the current through the motor.
Its default setting of TYPICAL is designed to work with motors whose inductance value is above 2.5 mH. You
should use the default setting for all AMCI motors except for the SM42 when it is parallel connected to the
SD17063. Non-AMCI motors that are series connected should also use the default setting. If you are parallel
connecting a non-AMCI motor to the SD17063, then calculate the motor’s small signal inductance. If the
inductance is greater than 2.5 mH then the default TYPICAL setting should work with your motor. If the cal-
culated inductance value is between 1 and 2.5 mH, the default setting will still work, but you may benefit by
reducing the current loop gain.
If you are using a parallel connected SM42, you may benefit from using the REDUCED 1 setting for the cur-
rent loop gain.
If you think that you will benefit from adjusting the gain, the easiest way to determine the optimum setting is
by actually testing the motor. See Determining Current Loop Gain starting on page 42 for the procedure to
set the current loop gain.
Current Control (SB2-1)
This setting has no effect if you are full stepping the motor.
Many microstepping drives control only the peak current to the motor. At low speeds, this type of current
control drops the available torque when microstepping the motor to 70.7% of that available when full stepping
the motor. By default, the SD17063 does not control the peak current to the motor, it controls the RMS cur-
rent. This means that the current applied by the SD17063 is always the power equivalent of the full step cur-
rent. Therefore, the motors’ full torque is always available. In fact, depending on the motors characteristics,
microstepping may even increase the available low speed torque.
RMS current is maintained down to 0.005 revolutions per second. Below this speed, the drive automatically
switches to peak current to prevent motor damage. If this creates a problem with your system, choose peak
current control. Be aware of the resultant drop in available low speed torque when microstepping the motor.
This setting is not latched. Changes to this setting are applied immediately. Be aware
that changing this setting while the motor is running may cause unexpected operation
because of the possible reduction in available torque.
Idle Current Reduction (SB2-2 & SB2-3)
The SD17063 can automatically reduce the current to the motor when it is not running to significantly reduce
motor heating. However, this also reduces the holding torque of the motor. If you choose an idle current
reduction setting, the current will be reduced after one second has passed without a step pulse from your
indexer. Once the motor receives a step pulse from the indexer, the motor current is immediately brought up
to its 100% value on the first step.
Two current reductions are available. To 0% reduces the motor current entirely. No holding torque will be
available when the motor is idle. To 50% reduces the motor current to one-half its maximum value. You can
also use the Not Reduced setting to always keep the full current applied to the motor.
When possible, you should always reduce the idle current to reduce motor heating and prolong the motor’s
life. The only time you should choose not to reduce the idle current is when you require the full holding
torque available from the motor.
This setting is not latched. Changes to this setting are applied immediately. Be aware
that changing this setting while power is applied to the motor may cause unexpected
operation because of the possible reduction in available holding torque.