Superior Electric SLO-SYN SS2000MD4M-O, Installation Instructions Manual

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Page 18 SS2000MD4M-O
4.8 INDICATOR LIGHTS
"FAULT" LED, Red
Lights to indicate over current condition. This condition is caused by motor
wiring errors or a ground fault.
Recovery from an over current condition requires removing and then reap-
plying the power.
SECTION 5: TORQUE VERSUS SPEED CHAR-
ACTERISTICS
5.1 MOTOR PERFORMANCE
All stepper motors exhibit instability at their natural frequency and harmonics
of that frequency. Typically, this instability will occur at speeds between 50
and 1000 full steps per second and, depending on the dy namic motor load
parameters, can cause excessive velocity modulation or improper position-
ing. This type of instability is represented by the open area at the low end of
each Torque vs. Speed curve.
There are also other instabilities which may cause a loss of torque at step-
ping rates outside the range of natural resonance frequencies. One such
instability is broadly defined as mid-range instability. Usually, the damping of
the system and acceleration/deceleration through the resonance areas aid in
reducing instability to a level that provides smooth shaft velocity and accu-
rate positioning. If instability does cause unacceptable performance under
actual operating conditions, the following techniques can be used to reduce
velocity modulation.
1) Avoid constant speed operation at the motor's unstable frequencies.
Select a Low speed that is above the motor's resonant frequencies and
adjust acceleration and deceleration to move the motor through unst-
able regions quickly.
2) The motor winding current can be reduced as described in Sec tion 4.5.
Lowering the current will reduce torque proportionally. The reduced en-
ergy delivered to the motor can decrease velocity modulation.