Rockwell Automation Publication 20P-TG004C-EN-P - September 2021
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Component Test Procedures
Chapter 2
Speed Feedback Device Tests
Check the Encoder
The encoder feedback device provides a dual channel quadrature output
waveform and requires that the output be differential line drivers at +5 or
+12…15V signal levels. The encoder power supply voltage and input selection is
controlled by DIP switch S21 on the control board (see “DIP Switch and Jumper
Settings” in the PowerFlex Digital DC Drive User Manual, publication 20P-
UM001). The encoder power supply from the drive can be measured from +V
(+) to COM (-) with a digital multimeter. If S21 is set to ENC_5, the voltage
level should be +2.5…5.4V. If S21 is set to ENC_12, the voltage level should be
+5.4V…15.2V. For reference, see
for a schematic diagram.
The Channel A and Channel B are square wave type outputs that are 90 degrees
out of phase. When rotating in the CCW direction, as viewed from the
commutator end, Channel A leads Channel B. Each differential channel has an
inverted and non–inverted signal.
Power for the encoder is provided internally and is capable of 200mA of current
with a current foldback feature that protects the power supply should the current
draw exceed 200mA. If different power supply requirements exist for the chosen
feedback device, the supply must be provided external to the drive.
The frequency is proportional to speed and the pulse rate of the encoder, referred
to as the “Pulse/Rev” rating on the nameplate. The speed of the motor can be
calculated by: Speed (RPM) = [Frequency (Hz) x 60]/[Pulses/Revolution].
Check the DC Tachometer
•
Verify that DIP switch S4 on the control board is set to the correct input
voltage of the DC analog tachometer. See “DIP Switch and Jumper
Settings” in the PowerFlex Digital DC Drive User Manual, publication
20P-UM001. Also, see
on page
for a circuit diagram.
•
The analog tach signal is fine scaled using parameter 562 [Anlg Tach
Gain].
•
See “Drive Reference and Feedback Scaling” in Appendix C of the
PowerFlex Digital DC Drive User Manual, publication 20P-UM001, for
more information.
