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Speed Control
Armature Voltage Feedback
The Focus 1 varies the speed of the motors mentioned above as a function of the Speed
potentiometer setting (or external speed command signal) by simply varying the output
Armature voltage (field excitation if used typically remains constant). Armature Voltage
Feedback (or simply Armature Feedback) does not require any special motor mounted
speed feedback device and is therefore inherently quite reliable and is capable of
providing up to 1% speed regulation.
Quick Stops
A non-regenerative drive cannot stop a motor faster than the motors normal coasting
rate unless a Dynamic Braking resistor is employed. The DB option provides a rather
quick stopping action and provides motor turning resistance when the drive is not in the
RUN condition. The Focus 1 can be outfitted with a Dynamic Braking resistor should
this requirement be desired.
Note: DB Resistors require Contactor Option - See Options
Power Outages
Shunt Wound Motors
Should a power outage occur, the drive would turn off and the motor would coast to rest.
If a Dynamic Braking resistor were employed there would typically be enough decaying
field strength to enable some faster stopping action but this should be tested from full
speed to determine if power outage stopping time is sufficient should this factor be a
safety consideration for your application.
Permanent Magnet Motors
Should a power outage occur, the drive would turn off and the motor would coast to rest.
If a Dynamic Braking resistor were employed, full Dynamic Braking force would be
exerted because the field is maintained by the motors internal permanent magnets.
Therefore, there would be motor turning resistance during power outages as well.
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