Rockwell Automation DC3R Regenerative DC Drive User Guide 1/4 - 2 HP, 115/230 VAC - Manual (Page 20)

12 Installation
Tachogenerator feedback
ATTENTION: Applying the incorrect polarity to the tachogenerator
can cause an overspeed condition. Make sure the positive (+) wire is
connected to terminal T1 and the negative (-) wire is connect to
terminal T2 when the motor is running in the forward direction. Failure
to observe this precaution could result in bodily injury.
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Using tachogenerator feedback improves speed regulation from
approximately 1% of motor base speed to approximately 0.1% of motor
base speed. Use tachogenerators rated from 7 VDC per 1000 RPM to
50 VDC per 1000 RPM.
Connect the tachogenerator to terminals T1 and T2 of terminal block 502
(TB502). The polarity is + for T1 and – for T2 when the motor running in
the forward direction. The polarity is reversed when the motor is running
in the reverse direction.