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Rockwell Automation Publication 20P-TG002B-EN-P - February 2018
Chapter 2
Component Test Procedures
8. Check the gate cathode junction of the field SCR/dual diode module.
With the digital multimeter set to “diode test” measure the resistance
across the modules (lead orientation is not critical). See
Table 11
.
If a low resistance is detected, replace the SCR/dual diode module (see
page
Table 11 - SCR/Dual Diode Module Gate Cathode Junction Measurements
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
). 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 counter clockwise 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].
Measure from
To
Nominal Meter Reading
XP1
XP2
10…20 Ω
XP3
XP4