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Installing the RD750
21
Encoder Output Wiring (continued)
The RD750 can output 5 Vdc or 12 Vdc differential signals.
, which is found on page 15, shows the location of the jumper used to set the out-
put voltage. Verify the input voltage range of any equipment you attach to the encoder
outputs. Operating the encoder outputs at 12 Vdc can potentially damage equipment
that is designed for a 5 Vdc signal.
Determining the TR Setting of a Control Transformer Resolver
Once the drive is powered, the RD750 may require configuration changes to work properly with a control
transformer resolver. A true RMS voltmeter or oscilloscope will simplify the process, but the Resolver Status
LED can also be used to make the changes.
With a True RMS Meter or Scope
1) Measure and record the voltage across the ±REF (R1-R2) connections on the resolver input connector.
2) Measure and record the voltage across the ±SIN (S2-S4) connections. If possible, rotate the resolver until
this voltage is at its minimum, which should be in the millivolt range.
3) Measure and record the voltage across the ±COS (S1-S3) connections.
If you were able to rotate the resolver until the ±SIN voltage was at its minimum
, the effective TR for your
control transformer is ±COS voltage / ±REF voltage.
If you were not able to rotate the resolver
, the effective TR for your control transformer is:
Refer back to the
section on page 16 and set your DIP switch settings to the closest opti-
mal TR setting that you can. Cycle power to the drive or issue a software reset command to re-initialize the
RD750. At this point, the LED2 Status LED should be on and green. If this is not the case, refer back to fig-
ure 4,
LED2 (Resolver State) Blink Patterns
on page 11 for additional information on the state of the resolver
connection.
With the Resolver Status LED (LED2)
If you followed the instructions for initial setup, you set the TR DIP switch settings to a value of 0.50. When
you apply power to the drive, LED2 on the RD750 will most likely be in one of three states:
On Green: Resolver is being read successfully
Blinking Red with a short “on” time: Resolver TR is lower than expected, decrease the DIP switch set-
ting.
Blinking Red with a long “on” time: Resolver TR is higher than expected, increase the DIP switch set-
ting.
In order to set the TR, you will have to:
1) Manually change the DIP switch settings either up or down depending on the state of LED2.
2) Cycle power to the drive or issue a software reset command to force the RD750 to read the state of the
DIP switches
3) Check the new state of LED2 and continue these steps until you find the proper setting.
Ideally, you will find the entire range of settings where the resolver can be read successfully and set the TR
setting to the center of this range.
TR
±SIN voltage
2
±COS voltage
2
+
±REF Voltage
=
